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Cite as: [2003] EWHC 812 (Ch)

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Neutral Citation Number: [2003] EWHC 812 (Ch)
Claim No. HC 02 C 00440

IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION
PATENTS COURT

Royal Courts of Justice
Strand, London, WC2A 2LL
15 April 2003

B e f o r e :

THE HONOURABLE MR JUSTICE LADDIE
____________________

ROCKWATER LIMITED
Claimant/Part 20 Defendant

- and -


(1) COFLEXIP S.A.
(2) TECHNIP OFFSHORE UK LIMITED
(formerly COFLEXIP STENA OFFSHORE LIMITED)

Defendant/Part 20 Claimant
Part 20 Claimant

____________________

Mr S Thorley QC and Mr T Mitcheson (instructed by Bristows for Rockwater Limited)
Mr R Miller QC and Mr J Turner (instructed by Norton Rose for Coxlexip S.A. and Technip Offshore UK Limited)
Hearing dates: 17 - 26 March 2003

____________________

HTML VERSION OF JUDGMENT
____________________

Crown Copyright ©

    Mr Justice Laddie:

  1. This action was commenced by Rockwater Limited ("Rockwater") which sought the revocation of European Patent (UK) 0 478 742 entitled "Device and Process for Unrolling Flexible Tubular Conduits Essentially Vertically". The defendant is Coflexip SA ("Coflexip"), the registered proprietor of the patent. Coflexip and Technip Offshore UK Limited, which is said to be the exclusive licensee under the patent, counterclaimed for infringement. That infringement involves Rockwater's ship, the Toisa Perseus, which was deployed in the execution of two pipelaying contracts in the summer and autumn of 2001. One contract was carried out in the Leadon field in water depths of about 120m, and the other in the East Foinaven field in water depths of about 300-500m. The jurisdiction under s.132(4) of the Patents Act 1977 is not in dispute.
  2. The patent has been litigated before in this country. Coflexip sued Stolt Comex Seaway MS Limited and two associated companies (together referred to as "Stolt") in respect of the operation of Stolt's pipelaying ship, the Seaway Falcon. Stolt attacked the validity of the patent relying in large part on allegations of obviousness based upon the prior use and disclosure of another pipelaying vessel called Apache. That action came before me. In a judgment dated 22 January, 1999, I found for the Coflexip both in relation to infringement and validity. That decision was upheld by the Court of Appeal, save that my finding of non-infringement in relation to claim 3 of the patent, was reversed.
  3. Whatever the outcome of the proceedings against Stolt, this is a different action which must be determined on the basis of the evidence relied on here. It should be noted that the alleged infringement relates to a vessel which is by no means to the same design as Stolt's Seaway Falcon. Furthermore, although allegations of anticipation and obviousness are raised here, the prior art relied on is quite different to that relied on in the previous action. There the primary prior art was the Apache. Here Apache is not pleaded. Instead, the primary prior art relied on consists of US Patent No. 4,721,411 and UK Patent Application No. 2,178,129, referred to during the trial as Recalde US and Recalde GB respectively
  4. The technical background

  5. The technical background to the patent is set out below. Although part of this is derived from the opening passages of my judgment in the Stolt action, it has had to be revised and expanded in certain areas to take into account the different evidence and different issues which arise in this action.
  6. The patent is concerned with a process and equipment for laying pipes and other conduits in deep water. It has particular application in off shore oil and gas fields. A variety of pipes and cables, some of very great length, may have to be used, for example, to connect the well to a site on dry land. The patent in suit is concerned particularly with the laying of flexible pipes and cables from a pipelaying ship and overcoming the problems associated with passing the pipe or cable from the ship into the water. It is convenient to start by considering the properties and behaviour of submarine pipes.
  7. There are different types of submarine pipes. Although they have many features in common and the same laws of physics applies to them all, in the art they are divided into two broad classes, namely rigid pipes and flexible pipes. The former are normally made of steel. Sometimes they are coated in concrete or plastics materials. They are capable of being laid in very deep water. The latter are normally made up of a number of layers of composites and reinforcing materials such as steel braids. Because their walls are made up of a number of interacting layers, those walls tend to be very thick. Most members of the general public would regard them as stiff or rigid. However, in the technical world of submarine pipes, they are considered to be flexible. As a practical matter those in the art have little difficulty in distinguishing one type of pipe from the other. There are difficulties associated with laying both, particularly in deep water. The two broad classes of pipes cannot be distinguished on the basis of size alone. Each can be made in a variety of sizes and their size ranges overlap. However, as Mr Nash, Coflexip's expert, explains, because of their thick walls, flexible pipes are much heavier than the same sized rigid pipes.
  8. The differences between typical rigid and flexible pipes can be explained as follows. A copper pipe used in a domestic water system can be regarded as rigid. If one end is clamped and the pipe is not too long, it will maintain an almost horizontal position without support at its free end. Its reluctance to bend can be referred to as its bending stiffness. If the end of the pipe is pulled down a bit it will flex. It is a bit "springy". When the force is removed, it will return to its original position. However, if more force is applied, a point will arrive at which parts of the pipe's surface will begin to stretch. It can be made to take up a permanently bent configuration. A plumber will do this by applying force to a copper pipe in a pipe bender. It is said to have been subject to plastic deformation. These characteristics were explained by Mr. Nash in his first report as follows:
  9. "15. Rigid pipe has a finite bending stiffness. That is to say, if a sufficient load is applied to a length of rigid pipe it will deflect (i.e. bend). A rigid pipe can be bent elastically up to its elastic limit. This means that provided the pipe is not bent beyond its elastic limit (or yield stress), it will return to its original shape after the bending force has been removed. If a rigid pipe is bent beyond its elastic limit, this will result in the pipe being plastically deformed. This means that if the bending force is removed, the pipe will not return to its original profile, ie a permanent curvature will be induced into the pipe.
  10. A plastically deformed pipe can, within limits, be returned to its original profile. This is achieved by applying a sufficient bending force to the pipe in the opposite direction to that which originally caused the plastic deformation. In other words, if a straight section of pipe has been plastically bent one has to overstress the pipe (i.e. apply a stress greater than the yield stress) in the opposite direction in order to straighten it. This process, if carried out correctly, will not affect the pressure containing properties of the pipe, nor its resistance to hydrostatic forces. However, if a rigid pipe is plastically bent beyond a certain minimum radius of curvature, called its ultimate bending radius, the pipe will suffer permanent localised buckling or crimping. This will irreparably damage the integrity of the pipe."
  11. These characteristics are exhibited by rigid steel submarine pipes. As long as they are not subjected to too much force they will be springy. If more force is applied they can be plastically deformed so as to take on a permanently bent shape. If they are bent beyond their ultimate bending radius, they buckle. It may take quite a lot of force to plastically deform a rigid pipe. If such a pipe is plastically deformed so that it adopts a curved shape, it will need to be plastically deformed again to return it to its straight configuration. Depending on the size and composition of the pipe, this also may involve the use of a lot of force.
  12. The behaviour of a typical flexible pipe is somewhat different. The bending stiffness of flexible pipe is far less than that of rigid pipe. The concepts involved can be explained sufficiently accurately for the purpose of this action by reference to the behaviour of a garden hose. If it is held horizontally at one end it will tend to droop. It has a much smaller ultimate bending radius than a rigid pipe, so it will have to be bent much more acutely before it buckles. On the other hand it is less readily plastically deformed. If bending force is removed from a flexible pipe or hose which has not buckled it will tend to return to its original shape. It is less prone than rigid pipes to acquiring a permanent bent shape. However if a garden hose is fed over a hose reel and a weight is put on the free end, the latter will tend to pull the hose down onto the reel. The greater the weight, the more pronounced this effect will be. Because the walls of the hose are comparatively flexible this has the effect of squashing the hose onto the reel. The cavity in the centre of the hose will become oval and, at some point, it will close completely. When this happens the pipe is said to be crushed. Again these characteristics were explained by Mr. Nash in his first report:
  13. "18. The bending stiffness of flexible pipe is several orders of magnitude less than that of rigid pipe. This is due to the lower bending stiffness of the materials which make up the flexible pipe and also because each layer is, to a degree, able to move relative to its neighbouring layer (in non-bonded flexible pipe). This means that flexible pipe can be bent to a much smaller radius of curvature than rigid pipe without exceeding its elastic limit. If one were to bend a flexible pipe beyond its elastic limit (also referred to as damaging bend radius or minimum bend radius), the pipe would be irreparably damaged so that it could not be straightened back to its original shape and its pressure containing properties would probably be impaired. However, flexible pipe can be bent to a very much smaller radius of curvature than rigid pipe without reaching its damaging bend radius. There is no plastic deformation with flexible pipe."
  14. Rockwater's expert, Professor Witz, explains that the distinction between rigid and flexible pipes is not sharply defined. He says that when bending is applied to rigid and flexible pipe, there is much in common ground in their resistance and behaviour. Both flexible and rigid pipe exhibit finite bending stiffness. He disagrees with Mr Nash's statement that there is no plastic deformation with flexible pipe. If a flexible pipe is subject to severe bending (i.e. it is subject to a "sharp" as opposed to a "gentle" bend), the innermost steel carcass may seize and plastically deform. But he accepts that the limiting bending criteria for rigid pipe are reached at a bending radius higher than the corresponding bend radius for an equivalent flexible pipe and that flexible pipe will have different parameters to rigid pipe. He points out that buckling and crushing can occur in both rigid and flexible pipes. However, because the walls of a rigid pipe are, by definition, comparatively rigid, they withstand crushing better. Thus rigid pipes are less sensitive to crushing and more sensitive to plastic deformation and buckling than their flexible equivalents. As was not in dispute, before laying a new pipe, load calculations should always be carried out to ensure that the pipe can be laid successfully with the apparatus available.
  15. Laying rigid submarine pipes

  16. When rigid submarine pipes were first laid in water from ships, they were fed off the back of the ship in a more or less horizontal direction. The ship is loaded with numerous lengths of straight pipe which are welded one by one on board to the end of the pipe being fed into the water. As more and more pipe is fed off the back of the ship, the weight of the unsupported pipe grows. This pulls down on the end of the pipe causing it to curve. This curvature of the pipe at the end near the laying vessel is called the overbend. To avoid permanent deformation here, the pipe is supported by a long curved guide, called a stinger. The stinger maintains a set minimum radius of curvature so that there is no plastic deformation of the pipe. With very rigid pipes (e.g. pipes of large diameter) being laid in very deep water, the stinger might have to be very long indeed. For example, a stinger of about 130 metres might be needed to lay rigid pipe in water 1000 metres deep. In such a case, the tension created by the 1000 metres of suspended pipe could be in the region of 60 metric tonnes. For that reason, where rigid pipe is to be laid in deep water, the stinger could extend well beyond the stern of the pipe-laying vessel. This could compromise the vessel's stability, particularly in rough weather.
  17. Furthermore in all cases steps have to be taken to ensure that the pipe does not contact the end of the stinger (or is carefully controlled on contact). The reason for this is that if the vessel suddenly backed up or moves forward too slowly relative to the pipe pay-out speed, there is a risk that the pipe will be bent more sharply (i.e. be subjected to a smaller bend radius) at the end of the stinger, thereby risking damage to the pipe. It may buckle at that point. Similarly, in adverse weather, the vessel may pitch and roll. If the pipe is in contact with the very end of the stinger and the stern of the ship rises as the prow falls, there will be a tendency to bend the pipe at an acute angle (i.e. a small bend radius) at the end of the stinger where it is no longer supported.
  18. The greater the depth of the water and the bigger the pipe, the greater the weight of the suspended pipe. Furthermore the vessel will be pulling in the direction of lay. The weight of suspended pipe and the tension imparted by relative movement of the vessel away from the pipe lying on the seabed will tend to pull the pipe towards the sea bed and off the ship. In some cases, the weight of the suspended pipe can be reduced by adding floatation devices to it as it is paid out. Indeed, pipe is normally laid in a sealed condition in which it is full of air since this will give it some buoyancy. Notwithstanding the adoption of these procedures, there will continue to be a substantial tension in the pipe tending to pull it off the vessel. This has to be prevented by means of some device on the vessel which pulls in the opposite direction. This can be done by a mechanical "hand" which pulls on the end of the pipe as it leaves the ship and stops it going overboard. The mechanical hand is called a tensioner. It must have the capacity to match the tension trying to pull the pipe off the vessel. Using more technical terminology, the tensioner "reacts" the tension in the pipe. In other words it acts as a brake on the pipe. Whichever terminology is used, the concept is the same; the suspended pipe under the influence of gravity pulls towards the seabed. To prevent the pipe moving in that direction in an uncontrolled manner, an equal and opposite pull has to be exerted, for example by the tensioner. The pipe can be likened to the rope being pulled by two teams in a tug-of-war. A great deal of energy may be expended by each team, i.e. each is applying a lot of tension in opposite directions, even though the rope does not move at all or only moves slowly. It can be said that the tension created by one team is being reacted by the other and vice versa. If either team lets go, the other will fall backwards. Similarly, if the pipe under the vessel is severed near the surface, the seaboard side will fall to the seabed and the vessel-side pipe will be brought back sharply on board by the effect of the tensioners.
  19. Thus the tensioner must have the capacity to exert a tension on the pipe which matches (i.e. reacts) the tension generated by the suspended pipe as it is being laid. In fact, it may need to have a higher capacity than that. As mentioned above, when the pipe is being laid it will normally be full of air. This gives it buoyancy. However the tensioner may be used to recover the pipe from the seabed in which event the latter may be full of water. The buoyancy will have disappeared. The pipe may now have an effective weight considerably greater than it had when being laid. The tensioner may be made up of a number of smaller tensioners in sequence capable of exerting a total pull which exceeds that of the suspended weight of pipe. Pipelaying in this fashion can be illustrated as follows:
  20. Figure 1:

    Figure 1
  21. In this Figure, the pipe-laying ship is being driven towards the right. If it were not, the end of the pipe where it leaves the stinger would be pulled hard down by the weight of the pipe below it. It would therefore be pulled down and might hit the end of the stinger. This could cause high localised forces which tend to buckle the pipe. This horizontal thrust of the ship results in the pipe lifting off the stinger before it reaches the end of it. Because the horizontal thrust lifts the pipe off the stinger (in other words reduces its tendency to fall down vertically), this can be used to reduce the overall length of the stringer to some extent. However increased horizontal thrust means greater use of the vessel's engines and this costs money. The location at which the pipe lifts off the surface of the stinger to enter the water is called the pipe suspension or lift off point. It will be appreciated that the location of this point will vary from time to time throughout the laying operation. The lighter the pipe being suspended and the greater the forward thrust of the vessel's engines, the "flatter" the take off trajectory of the pipe. This means that the pipe suspension point moves up the stinger towards the vessel. On the other hand heavier pipe (for example pipe being laid in deeper water) and lower engine thrust will result in a steeper take off trajectory of the pipe. In such circumstances the pipe suspension point moves down the stinger towards its seaboard end. Changes of the pipe suspension point will also be caused by pitching of the vessel due to adverse weather conditions. Professor Witz explained during his oral testimony that the stinger will be sized so the lift off point is broadly in the middle and the installer has some degree of latitude in adjusting the horizontal tension and, therefore, the effective lift off point to keep the pipe within its lay configuration.
  22. Figure 1 above also illustrates how the rigid pipe flexes. It describes an "S" shape in the water. As a result, this type of rigid pipelaying is called "S-lay". The deeper the water, the nearer the vertical the central section of the pipe will be as illustrated below.
  23. Figure 2:

    Figure 2
  24. Because in deep water the pipe will tend to take up the shape shown in Figure 2, an alternative type of rigid pipelaying can be used in such situations. The angle at which the pipe is fed off the end of the ship is matched, as nearly as possible, to the natural angle which the pipe will take up in the water (its so-called catenary shape). The result is that the pipe is fed off the end of the ship at an angle to the surface of the sea. This is illustrated in Figure 3 below. Because the pipe takes up a generally "J" configuration, this form of pipelaying is called "J-Lay".
  25. Figure 3:

    Figure 3

    In this illustration, the pipe is loaded onto the ship in short straight lengths. Individual lengths of pipe are lifted onto the angled ramp at the stern of the vessel, held by clamps and welded onto the upstanding end of the pipe which leads down into the sea.

  26. Needless to say, the deeper the water, the more near the vertical the top part of the pipe will be. There is a minor dispute between the parties as to how extensively J-Lay was practised before the priority date of the patent, but there is no dispute that it was well recognised as a possible way of laying rigid pipe and had been used.
  27. In both S-Lay and J-Lay one of the objectives is to prevent the pipe being bent at too acute an angle (i.e. with a small bend radius). If this is not avoided, there is a risk of the pipe buckling. A similar problem exists at the seabed. It will be seen in all the Figures above that the pipe curves up from its horizontal position on the seabed. This is called the sag bend. Once again, the pipelaying must be conducted in a way which ensures that the bend radius at this point is not too small for the pipe being laid. This is a point which will be considered more fully in a moment.
  28. Up to this point, pipelaying of rigid pipe has been described which involves welding together straight lengths of rigid pipe. Rigid pipe can be bent and spooled onto a large reel. This involves plastic deformation of the pipe. If the pipe from such a reel is laid from a pipe-laying vessel, it will need to be plastically deformed back into its substantially straight configuration. The reel is supplied with drive motors. These may be used to spool pipe onto the reel. They can also be used to apply axial pull to the pipe so as to counter or react the axial tension created by the pipe suspended under the vessel.
  29. Laying flexible submarine pipes

  30. With flexible pipe the standard form of laying used in modest depths of water is to pass it more or less horizontally from a reel (sometimes called a winch) over a curved chute (sometimes called an "overboarding gutter") or wheel (called an "overboarding wheel", "laying wheel" or "sheave") and down into the water. The catenary of such pipe from the point where it leaves the gutter or wheel to the sea bed is J-shaped although, because of the shape of the path taken by the pipe from the reel to the seabed, this is sometimes referred to as S-Lay. Once again, to prevent the weight of pipe under the ship from stripping the rest of the pipe from the reel, some form of tensioning device is used to react the tension created by the suspended pipe. This can take the form of tensioners or the wheel on which the pipe is loaded can be powered. The "Recommended Practice for Flexible Pipe" API 17B published by the American Petroleum Institute in June, 1988 illustrates both of these methods and describes them as the most common. These illustrations are set out as Figures 4 and 5 below.
  31. Figure 4:
    Figure 4
  32. In 1990, powered reels were not suitable to lay flexible pipe in deep water where a tension capacity of more than typically 30 tonnes was required. Mr Coutarel, Coflexip's Product Research and Development Manager, said that at that time the tension capacity provided by the reel was around 10-30 metric tonnes. This was to be compared with linear tensioners. Mr Nash explained that in the Norske Shell Draugen field in about 1992, tensioners of 60 tonne capacity were used and Mr Coutarel explained that Coflexip used a tensioner of 125 tonne in 1991. Furthermore tensioners can be used in series. Accordingly, linear tensioners were used to provide the tension when greater than 30 tonne tension capacity was required. An arrangement using tensioners is illustrated in Figure 5 below.
  33. Figure 5:

    Figure 5
  34. The use of the laying wheel illustrated in this Figure and the chute in Figure 4 is to prevent the pipe from being crushed (i.e. flattened) by the effect of the weight of the line below the ship. The increased crushing forces produced by laying heavier pipe in deeper water can be offset by increasing the radius of the chute or wheel over which the flexible pipe is overboarded into the water. This was described by Mr Nash in his first report in a passage which he said was common general knowledge:
  35. "Crushing of the pipe at the overboarding point
    36. As the water depth increased, the tensile load in the pipe also increased due to the greater weight of suspended pipe. The increased tensile load became a particular concern where the pipe passed across the overboarding gutter (or wheel). The gutter provided the reaction to a combination of the tensile load in the pipe between the gutter and the installation reel or tensioner, and the free hanging pipe suspended from the gutter. This reaction was spread approximately uniformly over the length of the contact between the pipe and the gutter. If the radius of the gutter and, therefore, the pipe contact length, were to remain the same, the crushing force per unit length of contact increased as the water depth and pipe suspended weight increased. To avoid or minimise the increase in crushing load as the water depth increased, one had to increase the radius of the gutter, and hence the contact length. In this way the increased crushing load was compensated by an increase in the support length."
  36. In the case of flexible pipes, just as with rigid pipes, there will be a sag bend at the junction between the pipe lying horizontally on the seabed and the near vertical portion leading down from the pipe-laying vessel. Again, if this sag bend is too acute, there is a risk that the pipe will be deformed at the bend. To avoid this, the vessel is driven in the pipe-laying direction so as to impart tension to the line in a horizontal direction. It will be appreciated that the same effect is achieved with rigid pipe. This is, in substance, a mirror of what happens on the stinger – as the vessel is driven forward the pipe takes a more shallow trajectory. Whether considering rigid or flexible pipe, additional tension applied in the direction of lay reduces the angle of the sag bend and thereby reduces the risk of damage to the pipe at that location. This effect is illustrated in the following figure.
  37. Figure 6:
    Figure 6
  38. The drawing on the left illustrates a case where there is no forward motion of the pipe-laying vessel. The one on the right is an exaggerated depiction of the effect of driving the vessel to the right. In the left hand drawing, the only tension in the pipe is the vertical one trying to pull the pipe towards the sea. The vessel has to counter or react this tension. In this case it is the reel to the right of the vessel which reacts that tension. In the right hand drawing, the tension in the pipe can be considered to be made up of two components. One is the vertical component generated by the effect of gravity on the suspended pipe. It is pulling the pipe towards the seabed. The second is a horizontal component which is trying to pull the pipe to the left. Both of these components have to be reacted on the pipe-laying vessel. Mr Nash explained the use of horizontal forces to avoid problems at the sagbend as follows:
  39. "In order to prevent the pipe buckling at the sagbend a horizontal tension was applied to the pipe by tensioners situated on the deck of the vessel. In this way a minimum radius of curvature was maintained at the sagbend. This avoided the risk of the weight of the pipe tending to straighten itself vertically and creating overstress in the sagbend (caused by a small radius of curvature)." (First Report paragraph 85)

    Although in this passage he was discussing the sagbend problem in relation to rigid pipes, the same principles apply to flexible conduits as well.

    Overboarding accessories

  40. Flexible pipes are normally made in the factory in very great lengths. Mr Coutarel gave evidence that a flexible pipe with an 8 inch internal diameter may be made in individual lengths up to 10 km and a 12 inch pipe may be made in individual lengths of up to 5 km. These lengths have to be joined together. Each length of pipe has an end fitting at each end. To extend a flexible pipe, the end fitting on one length must be connected to the end fitting on another to make what is known as an intermediate connection. Mr Coutarel explained that end fittings vary between 0.5 and 4 metres in length depending on the size of the pipe and its application. So an intermediate fitting may be from 1 to 8 metres in length. End fittings are made of steel and usually have a diameter twice the diameter of the flexible pipe to which they are fitted. They are rigid. Other types of rigid accessories which are installed on flexible pipe during production are bending stiffeners which are used on pipes called dynamic risers. Bending stiffeners are generally up to 7 metres long and are made of steel and polymer material. The diameter of a bending stiffener is normally 3-4 times the size of the diameter of the flexible pipe. There are other rigid accessories such as buoyancy modules and anodes.
  41. These rigid accessories have to be overboarded. This means that they have to be fed over the gutter or wheel and fed into the water. If such an accessory is fed round a wheel or gutter, the tension in the pipe will act on the pipe/accessory junction to give very high buckling forces over a very short distance. The problem is illustrated in Figure 7 below.
  42. Figure 7:

    Figure 7
  43. This propensity for local buckling has been a serious problem where the laying of flexible pipe is concerned. A significant number of possible solutions have been proposed and quite a few of them have been put into practice. Coflexip gave evidence relating to, and produced drawings of, some of these. Mr. Coutarel explained that one way of overboarding the rigid accessories without damaging the pipe is to use a crane or the so-called A-frame which is sometimes located at the stern of the vessel. As the rigid accessory is unrolled from the reel, the laying operation is halted before the rigid accessory reaches the overboarding gutter. The crane hook is attached to the rigid accessory. In this way the tension load from the weight of the suspended pipe is transferred from the reel to the crane which then operates to lift the rigid accessory up and over the overboarding gutter. The crane then lowers the pipe and the rigid accessory attached to it below the level of the overboarding gutter. If the rigid accessory is an intermediate connection between two lengths of pipe, the tension is then taken up once again by the reel and the crane is disconnected from the rigid accessory. The laying process then continues. In this case, during the operation of the crane, the powered reel no longer pulls the pipe. The load is taken by the crane.
  44. Another arrangement used and published before the priority date of the patent in suit operates as follows.
  45. Figure 8(a):
    Figure 8a
  46. This shows the flexible pipe being fed from the tensioners at the right towards the laying wheel. The drawing illustrates a case in which some 300 tonnes of pipe is suspended off the end of the vessel. The rigid accessory is approaching the upper surface of the laying wheel. At this point a lift off device which is located between the tensioner and the laying wheel and is normally not in contact with the pipe, is lifted up so as to support the underside of the pipe and push it in an upward direction. This has the effect of lifting the right hand end of the accessory. This is illustrated in Figure 8(b) below.
  47. Figure 8(b):
    Figure 8b
  48. The lift off device continues to rotate until it is in a position to allow the accessory to travel vertically past the laying wheel as shown in figure 8(c) below.
  49. Figure 8(c):
    Figure 8c
  50. Finally the lift off device is pulled back to its original position.
  51. Figure 8(d):
    Figure 8d
  52. It will be seen that although the pipe and the accessory are kept under tension at all times, the arrangement avoids there ever being an occasion on which there is any bending at the accessory/pipe junction.
  53. Further methods for overboarding involve moving the accessory round the laying wheel or overboarding gutter under very little tension. One method of doing this, which was the subject of a Coflexip patent, is illustrated below.
  54. Figure 9:

    Figure 9
  55. A collar is fitted around one of the end fittings and cables (9) are attached to it in order to connect it to the winch used when a pipe has to be abandoned, e.g. because of bad weather, and recovered (hence the name "A&R" winch). The tension load is transferred from the tensioners to the A&R winch. The tensioners are then opened and the A&R winch cable is unreeled to allow the intermediate connector to pass through the tensioners. Unreeling is continued until the collar reaches a tilting frame (5). When the collar reaches the tilting frame it automatically engages with the frame. By continuing to unreel the A&R winch cable, the tilting frame is able to rotate and thereby lift the intermediate connector off the wheel. The tension applied inboard of the tilting frame, e.g. by the tensioners, is turned off or reduced. This means that there is bending but no significant tension on the vessel side and tension but no bending on the sea side of the intermediate connector. It will be appreciated that this is similar in principle to the use of the A-frame discussed in paragraph 28 above. This is illustrated in the following Figure.
  56. Figure 10:

    Figure 10
  57. Once the tilting frame has completed its rotation, the collar automatically disengages from the frame. The tension is transferred back to the tensioners and the A&R winch cable is disconnected. The tilting frame is brought back on board and normal laying is resumed.
  58. Summary of the relevant problems in laying flexible pipe.

  59. From what has been said above, it can be seen that among the problems facing those wishing to lay flexible pipe were the following. First there is a need to avoid bending the pipe at the interface between the pipe and the rigid accessory at the same time as a high axial tension is being applied at that point. If a high axial tension is applied to the pipe at the interface at the same time as it is subjected to bending stress, there is a risk that the pipe will become damaged. Second there could be a problem which arises out of the radial contact loads induced by the axial tensile load (pipelay tension) when the flexible pipe is bent around the overboarding gutter or wheel. These contact loads are generally acceptable in shallow or medium water depth, but they tend to crush the pipe in deep water. The same problem exists if high axial tension is applied to the pipe while it is spooled on its reel.
  60. The Coflexip Patent

  61. The patent was analysed and the claims were construed in the Stolt action. Neither Mr Miller QC for Coflexip nor Mr Thorley QC for Rockwater has invited me to depart from any of the relevant holdings made there. However the issues of validity and infringement in this action are different and matters which were of no or little importance in the Stolt action are central to this dispute. For that reason, and to ensure that this judgment is self-contained, it is necessary to look again at the patent and its claims.
  62. The opening paragraph of the specification states that the invention relates to a method and a device for effecting the laying of "flexible conduits, in particular of tubular flexible conduits". Later it says that the invention is to cover "the laying of cables, for example traction cables and above all electric cables. Electric cables are understood to mean any cable comprising electrical conductors, as well as power cables and cables carrying information". In the Stolt action, the Court of Appeal held that the latter passage:
  63. "establishes that the words "flexible conduit" should be interpreted as including more than what was known as flexible pipe, but not so widely as to cover what was known in the industry as rigid pipe." (paragraph 18)
  64. Only one point need be added to that. There is nothing in the specification or the claims which imposes a lower or upper limit on the diameter of flexible conduits covered by the patent nor is there any limit on the type of construction adopted or, for example, the surface characteristics of the conduit. The expression is wide but excludes rigid pipes.
  65. The specification goes on to describe some of the prior art and to identify some of the problems which are to be addressed by the invention. It refers to the methods of laying of the type illustrated in Figures 4 and 5 above and comments that:
  66. "For the purpose of being able to lay flexible conduits with relatively large diameters in great depths of water, one has to use tensioning means and deflecting elements whose dimensions and cost pose problems and which create an excessive space requirement on the bridge of the laying vessel" (page 1 lines 33 to 36)
  67. As explained above, a concern when laying flexible pipe in deep water is the possibility of crushing. This can be addressed by employing overboarding wheels or chutes of larger diameter. This is addressed in the specification. It comments on the effect of laying such large diameter flexible pipes in deep water on the dimensions of the pipe reel or winch on which the pipe is stored onboard:
  68. "Such a winch, as well as the deflecting element, assume dimensions and space requirements that are excessive when the diameter of the conduit and the depth of water increase. As the diameter of the tubular flexible conduit and the depth increase, the size of the wheel becomes increasingly larger. Such a wheel may have a diameter of the order of 10 metres for a depth substantially equal to 500 metres." (page 1 lines 43 to 49).
  69. It then goes on to state that:
  70. "With the devices of the known type, it is not possible to exceed this order of depth. Wheels with a larger diameter are difficult to make." (page 1 lines 51 to 54)
  71. The specification then states that there is an additional problem with overboarding accessories. It acknowledges that there are known ways of overcoming this problem, but suggests that the equipment for doing it becomes excessively bulky when trying to overboard large pipes in deep water. Once again it says (page 2 lines 16 to 20) that it is not possible to exceed a depth of water of the order of 500 metres when the internal diameter of the tubular flexible conduit to be laid reaches approximately 30 cm (this would be a pipe with an outside diameter of about 18 inches). The specification then sets out the purpose of the invention as follows:
  72. "The object of the present invention is the laying of flexible conduits at depths that are substantially greater than those which are feasible by using the known means, as, for example, a depth of the order of 1000 to 2000 metres. The device in accordance with the present invention must be capable of withstanding considerable tractive forces which may reach and even exceed 250 tons in the case of a conduit with a diameter substantially equal to 30 cm for a depth of 1000 metres." (page 2 lines 37 to 44)
  73. Thus one of the objectives of the patent is to enable large flexible pipe to be laid in water deeper than about 500 metres. However, as will be seen when considering the claims, there is nothing to limit them to a laying process or equipment at any particular depth. For that reason, the fact that the two pleaded acts of pipelaying by the Toisa Perseus took place in water significantly shallower than 500 metres is irrelevant to the issue of infringement. Furthermore, there is no lower limit on the tractive forces which apparatus falling within the claims must be capable of handling.
  74. A major part of Coflexip's invention is the idea of positioning the tensioning means vertically so that the flexible pipe leads directly from the tensioning means down into the water. The way this works is illustrated as follows in the patent:
  75. Figure 11:
    Figure 11
  76. This depicts a laying vessel (1), which has a basket (2) in which the flexible pipe or conduit (3) is stored. The pipe is led from the basket up over a wheel or, as illustrated, a chute (4) which is located at the top of a derrick (5) towards the middle of the ship. The chute acts as a guide. The conduit hangs down from it inside the derrick in a substantially vertical direction. Inside the derrick the conduit passes down between tensioning devices (6) of the caterpillar variety (11). These grip the conduit and support it. Because the tensioning devices are disposed vertically, they make it possible to lower the conduit in a substantially vertical direction through a hole in the middle of the ship, generally referred to as a moonpool (8). Just before the moonpool there is a working table (7) which can be used if work has to be performed on the pipe before it enters the water, for example if it is necessary to add an additional accessory to it.
  77. As shown in this drawing, before it enters the mouth of the first tensioner at the top of the derrick, the flexible conduit is subject to very little tension. This is depicted by the sag (3) between the basket (2) and the chute (4). Because at this point the conduit is not under tension it sags under its own weight. The drawing depicts two conduits in this location. The specification explains that this is to demonstrate the sag which will exist in a small conduit (the top one depicted in broken lines in the Figure) and that which will exist where a larger one is being laid (the bottom one in solid lines). The specification explains the advantage of using vertical tensioners:
  78. "In these conditions, the tension ahead of the tensioning means being exerted on the portion of the flexible conduit up the line and coming from the storage means is very low and preferably virtually negligible. It has been found that in these conditions, it becomes possible to subject a portion of the conduit situated in the portion ahead, between the storage means and the tensioning means, to relatively extensive bending, this being explained by the fact that in this case, there is no combination of the bending with an axial tractive load" (page 2 line 52 to page 3 line 7)
  79. The patent also describes how the parts of the conduit carrying accessories or end fittings are passed through the tensioners. Because accessories and end fittings have a diameter significantly larger than that of the conduit, the tensioners are opened up to allow them to pass through. While this is happening the open tensioners can apply no tension to the conduit. Consequently the accessory is attached to a winch which takes the strain while tensioners are open. Once the accessory has passed through, the tensioners are closed and the accessory can be disconnected from the winch. How this is done in relation to an end fitting is illustrated in the patent as follows:
  80. Figure 12:
    Figure 12
  81. Drawing (a) shows the conduit (3) being supplied over the chute (4) to the top of the derrick (5). It passes down between, and is gripped by, the caterpillar tensioners (6, 11), passes through the open working table (7) and down through the moonpool (8). Above the derrick is a winch (19), which is also just visible at the top of the derrick in Figure 11 above, from which hangs a cable (20). What happens when an end fitting has to be lowered through the derrick and attached to the end fitting at the beginning of the next length of conduit is illustrated in drawings (b) to (h). The cable is attached to the fitting and the winch takes up the strain. The caterpillar tensioners are then opened and the winch allows the end fitting to be lowered to the level of the working table which then shuts to prevent the end fitting from moving about laterally. The end fitting is clamped in this position and the cable (20) is released and wound back up by the winch. The end fitting at the beginning of the next length of conduit is then passed down through the derrick. The two end fittings (21a and 21b) are joined together. The caterpillar tensioners are closed and can resume taking the strain. The working table is opened and the vessel resumes laying. The same procedure, but without the need to join two end fittings, is used if the accessory is pre-fitted to the conduit.
  82. The specification contains no details of the design and operation of the caterpillar tensioners. This is because such devices were well known at the priority date of the patent. They have opposing tracks which press on the outside of the conduit. Operation of the motors which drive the tracks causes the conduit to be moved forward or backwards. Normally they have reversible motors. Thus there are mechanisms which can drive the opposing tracks towards each other so as to grasp the conduit to stop it slipping through the tensioner and or drive them apart so as to release the conduit. There are also motors designed to apply axial tension to the gripped conduit. What is happening can be understood by reference to someone lifting a rope at the end of which is a heavy weight. The muscles in the hand enable the hand to grasp the rope and the muscles in the arm apply the force to do the lifting.
  83. As the above description indicates, the tracks can be moved towards or away from each other. This is also necessary to allow the tensioner to operate with different diameter conduits. As Mr Nash agreed, opening a tensioner was a conventional method of allowing accessories to pass (Transcript Day 2 page 234). The concept of opening and closing the tensioner to allow accessories to pass adds nothing inventive to the patented system. I do not understand Mr Miller to suggest otherwise.
  84. There is one other passage which is of significance to the issues I have to decide. At the end of the specification is the following passage:
  85. "One of the original features of the invention lies in the absence of any means for guiding the tubular flexible conduit after it has left the main tensioning means. However, it should be noted that the main tensioning means 6 can themselves ensure guidance for the tubular flexible conduit and a deviation relative to the vertical. For example, the multi-caterpillar tensioning means generally permit a deviation of more or less 10 to 15o relative to the vertical." (page 10)
  86. The second half of this passage contemplates that the tensioner is designed in such a way that it can operate to "guide" the conduit when the top of its catenary is up to 15o from the vertical.
  87. The Claims

  88. There are nine claims. Claims 1 and 2 are process claims. Claims 3 to 9 are apparatus claims. Although many of these are said to be in issue, Claims 1 and 3 are the most important and it is convenient to consider them first. Claim 1 is as follows:
  89. "A process for laying from a floating support (1), a flexible conduit (3) comprising a rigid accessory (21, 21a, 21b) mounted on the said flexible conduit (3) and having an outer dimension larger than the outer diameter of the latter, wherein one unrolls a flexible conduit (3) gripped at its outer surface by linear winch-type tensioning means (6) with a substantially vertical axis, and wherein
    (a) to cause the section of the flexible conduit (3) whereon the accessory is mounted to pass through the said tensioning means (6), the said rigid accessory (21) is connected to auxiliary tensioning means (19, 20), so as to take up the pull exerted by the flexible conduit (3) by the said auxiliary tensioning means (19, 20), while the flexible conduit (3) is lowered through the free space between the said laterally moved-apart tensioning means (6),
    (b) the outer surface of the flexible conduit (3) is gripped ahead of the rigid accessory by the said tensioning means (6) after they have been brought together, so that the pull exerted by the flexible conduit (3) is again taken over by the said tensioning means (6);
    (c) after the auxiliary tensioning means (19) have been released, the unrolling of the flexible conduit (3) is resumed by the said tensioning means (6), the latter comprising the last means for guiding the conduit at the level of the floating support."
  90. Although this covers a process designed to achieve the benefits described by the specification, it should be noticed that there is no limitation to operating in deep water or using small overboarding equipment nor is there any limit to the size, weight or construction of the flexible conduit. The claim covers a method of laying flexible conduit, whether or not anything else, for example a rigid pipe, is being laid at the same time. Furthermore, the claim does not refer to the design of the equipment upstream of the tensioner. As can be seen in Figure 11 above, the drawings in the patent illustrate the use of a chute (4) over which the conduit and accessories pass before taking up a vertical orientation. This is described in the specification. However there is no requirement in the claim that that there should be any such device or, if there is a device, that it should be a chute. Thus the claim would cover the process carried out on a vessel fitted with an overboarding wheel or sheave (see Figure 5 above) feeding the conduit and accessories into the top of the vertical tensioner. Furthermore, there is no requirement that there be a moonpool. The pipe could be paid out over the stern of the vessel. Thus the purely structural features of the claim would be met by a device of the following general arrangement:
  91. Figure 13:
    Figure 13
  92. I have already discussed the meaning of the expression "flexible conduit" (see paragraph 39 above). In the previous action, the meaning of the words "the pull exerted by the flexible conduit is again taken over by the said tensioning means" was considered. The Court of Appeal held as follows:
  93. "21. The pull referred to in the claim is that exerted by the flexible conduit seaside of the main tensioners. Thus the words "the pull" refer to all the tension caused by the part of the pipe seaside of the main tensioners. The sentence bridging pages 2 and 3 of the specification, relied on by Stolt, does not suggest a contrary meaning. All that is said is that, if the seaside pull is taken by the main tensioners, the tension in the pipe after the main tensioners "is very low and preferably virtually negligible". There will inevitably be some tension due for example to the weight of the pipe and the friction, but that does not detract from the teaching of the specification that the tension from the pipe seaside of the tensioners is to be taken by the main tensioners or, when an accessory is passed, by the auxiliary tensioner.
    22. Of course, the words "the pull" have to be construed in context. As Lord Diplock pointed out in Catnic Components Limited v Hill & Smith Limited [1982] RPC 183 a word such as "vertical" had to be construed in context; in that case in the context of manufacture of lintels for the building trade. Thus the requirement that a metal beam should be vertical did not mean that it should be exactly 90o to the horizontal. A similar approach should be adopted in the present case so that the requirements as to "the pull" should be construed in the context of pipelaying from a ship."
  94. It is apparent that some tension can exist on the vessel side of the tensioner. This is said to be "very low". In the Stolt action it was not necessary to consider just how low this tension had to be. To apply the purposive construction suggested in Catnic, it is necessary to have in mind the reason why the inventor requires all or most of the pull to be taken by the tensioner. As pointed out above, when laying flexible pipe in deep water there is an increased problem with high tension on the pipe causing crushing on the overboarding chute or wheel and also with that tension making it more difficult to overboard accessories. A major purpose of the invention is to avoid these problems. Taking all or a large part of the pull on the vertical tensioner has the effect of reducing the tension upstream, thereby solving these problems. Therefore these benefits of the invention are secured if the tension upstream of the tensioner is kept low enough that overboarding of accessories and crushing are no longer a problem. Subject to ensuring that those requirements are met, a small amount of tension upstream of the tensioner is permissible. For example, spooled pipe tends to unravel itself from the reel unless it is maintained under some tension. A process which would otherwise fall within the claim does not fall outside it by reason of the fact that sufficient tension to avoid unspooling is maintained between the tensioner and the reel of conduit as long as that tension is well short of the level to cause crushing and overboarding problems.
  95. The only other part of Claim 1 which need to be considered are the words "last means for guiding" in the phrase "the said tensioning means (6) comprising the last means for guiding the flexible conduit (3) on board the floating support". Similar words are to be found in claim 3, the first product claim. It is convenient to consider them in relation to that claim.
  96. Claim 3 is in the following terms:
  97. "A device for operating the process according to any one of the claims 1 and 2, comprising;
    - linear winch-type tensioning means (6) with a substantially vertical axis, capable of ensuring the normal lowering of the flexible conduit (3) by gripping the outer surface of the flexible conduit (3) and capable of being laterally moved apart, the said tensioning means (6) comprising the last means for guiding the flexible conduit (3) on board the floating support (1),
    - auxiliary tensioning means (19, 20) comprising at least one elongate movable traction element (20) capable of being connected to the rigid accessory (21, 21a, 21b) mounted on the flexible conduit (3)."
  98. This product claim consists of two parts. First, the device must be "for" operating the process of Claims 1 and 2. Second it sets out a number of structural integers which must be present in the device.
  99. In the Stolt action I had held that the words "a device for operating" should be construed as meaning "when used for". As the Court of Appeal pointed out, that construction would have made the apparatus claims otiose. Such claims could only be infringed when there was also infringement of the process claims so the former would have become largely redundant. The Court of Appeal held that the words should be construed in the normal way so that the claim covers devices "suitable for operating" the patented process (see Court of Appeal judgment paragraphs 23 to 27). For example if the pipelaying vessel depicted in the drawing in the patent (see Figure 11 above) had a large motor attached to the reel (2) and it was always used to provide most of the tension needed to keep the pipe suspended in the sea, it would still be within the scope of the patent because the apparatus would still be suitable for or capable of operating the process covered by claims 1 and 2. The construction adopted by the Court of Appeal not only avoids the redundancy which would have existed had my interpretation been correct, but it also creates certainty. Instead of the apparatus passing in and out of infringement depending on how it is used, it always infringes as long as it has the capacity to operate in accordance with the process claims and meets the structural requirements of the claim. The vessel depicted in Figure 11 falls within the device claim even if it has no pipe on board and is in dry dock.
  100. This is of considerable importance in this case because Coflexip accepts that Rockwater has not infringed the process claims. Its case of infringement is that the Toisa Perseus meets all the hardware requirements of the device claims and is capable of being operated in a manner which would fall within the process claims even though Rockwater has not operated it in that manner and, as far as I am aware, has never threatened to do so. Since this is so, the alleged infringement must consist of the commercial presence of the Toisa Perseus in the Leadon and East Foinaven fields, not the pipelaying operation conducted there.
  101. Specific functional capability is a feature of a number of other integers in this claim. Thus, the linear winch-type means (i.e. the tensioner) has to be "capable of" ensuring normal lowering of the conduit and "capable of" being moved laterally apart. Similarly the auxiliary tensioning means (i.e. the A&R winch) has to be "capable of" being connected to a rigid accessory mounted on the flexible conduit. Neither the tensioner nor the A&R winch need be performing these functions for the requirements of the claim to be met. It should be noticed that this claim does not require the presence of a flexible conduit or any rigid accessory attached to it. Once again, this means that a pipelaying vessel can fall within the claim even if it is not carrying out a pipelaying operation. I do not understand there to be any dispute between the parties on this issue.
  102. The only dispute as to the meaning of the claim centers on the requirement that the hardware in the apparatus must include a tensioning means "comprising the last means for guiding the flexible conduit on board the floating support".
  103. Mr Miller advances two constructions for the words "means for guiding". First he argues that, in the context of the patent, these words should be taken to be a reference to the well known wheels, gutters or chutes of the prior art. As he puts it in his opening skeleton argument, "that is the sort of device that must be absent after the tensioning means". The alternative construction proceeds as follows. He accepts that the word "for" in "means for guiding" should be interpreted in the same way as the Court of Appeal interpreted it in the context of "device for operating". In other words it means "suitable for". He argues that the words in the claim should then be construed as meaning "capable of comprising the last means for guiding the flexible conduit"[1].
  104. I do not accept the first of these arguments. There is nothing in the specification to suggest that the word "means" is to be limited to wheels, gutters or chutes of the prior art and devices of the same sort. "Means" is one of the most frequently used words in patent specifications. It is used to encompass anything capable of carrying out a specified function. This is consistent with how it is used in Coflexip's patent. The only passage in the specification which deals with this feature of the invention is the one set out at paragraph 53 above. There the inventor refers to "any means". In my view, the word has its normal meaning in claim 3. It covers any structure for guiding the flexible pipe.
  105. I also do not accept Mr Miller's second argument. The claim does not say "capable of comprising the last means for guiding the flexible conduit" as he suggests. Having accepted that the word "for" means "capable of", he has then re-written the claim as if it read "for comprising the last means for guiding" by notionally inserting "for" in front of "comprising". It will be recalled the relevant section of the claim provides that the tensioner is to be "capable of" ensuring normal lowering of the flexible conduit and "capable of" being laterally moved apart but it must also "comprise" the last means for guiding the flexible conduit. In my view this imposes a mandatory requirement that the tensioner be the last means for guiding. It is not enough that it is "capable of being" the last means as Mr Miller suggests.
  106. To determine the meaning of the expression "the last means for guiding", it is necessary to consider separately the meaning of "means", "for" and "guiding". The first of these has been considered already. Mr Miller and Mr Thorley agree that the second has the same meaning as in the words "for operating the process" in claim 3 namely "suitable for". The point of difficulty is as to the meaning of the word "guiding".
  107. In the Stolt action, the meaning of "means for guiding" was considered. The relevant part of my judgment reads as follows:
  108. "By the end of the trial, only one issue on infringement remained. Claim 1 ends with a requirement that the vertically disposed tensioning devices are "the last means for guiding the conduit at the level of the floating support." Similar wording is to be found at the end of Claim 3. This wording reflects the fact that since the patented system delivers the flexible conduit at the same angle as the catenary below the vessel, no further guides, such as stingers or overboarding wheels or chutes, are required. As the drawing in the patent (Figure 14 above) illustrates and the text describes, below the lowest tensioner there is the working table (7) and the moonpool (8). Neither the table nor the sides of the moonpool are described or referred to in the specification as guides. In normal and stable conditions, they do not even touch the conduit.
    The layout of the Seaway Falcon, the Stolt Comex vessel which is alleged to infringe, is essentially the same as that illustrated in Figure 14. It includes bumpers or deflectors located below the tensioners to prevent pipe which is being laid from hitting the moonpool or moonpool doors. It was accepted by Stolt Comex that in normal use these devices do not touch the pipe. They are used to prevent the pipe from being damaged, for example by smashing against the edge of the moonpool doors during stormy weather. Mr. Willis, who had never seen the Seaway Falcon in operation, said that the pipe would touch the deflectors "every other second". I do not accept that evidence. When the whole of his cross examination on this subject is reviewed and read in the light not only of Mr. Seeley's evidence but also Mr. Coutarel's evidence, it is apparent that the vessel is designed to be operated without the pipe contacting the deflectors at all. The same point comes out of the written instructions given to the operators of the Seaway Falcon. They are told to set up the vessel to ensure that there is no "clashing with the bottom edge of the moonpool". Those instructions go on to explain that if the pipe does come into contact with the bottom edge:
    "This will not cause any damage to the [pipe] if performed in a fully controlled manner as the base of the vessel moon pool has a 7.5 metre radius"
    This means that because the edge of the moonpool is rounded (because of the presence of the deflectors) pulling the pipe past it will not cause damage if done carefully.
    I do not accept that the deflectors in the Seaway Falcon can reasonably be called guides. They are no more guides than the bumpers at the front of a car or a crash helmet worn by a motorcyclist. The defendants infringe."
  109. This passage was approved in the Court of Appeal. As Mr Thorley points out, whilst this conclusion was sufficient to dispose of the question of infringement in that action, it does not help to determine what the scope of the expression "means for guiding" is. In particular it does not resolve the ambit of the word "guiding".
  110. I think the simplest starting point is to consider an example discussed during the trial. If a man and a woman walk down a straight road while holding hands, neither is guiding the other. If the man gently pushes the woman in a different direction, he is guiding her. He is applying a lateral force to ensure that she takes another direction. As Mr Miller argues, if a pipe is hanging vertically in water and it passes through a hole in a plate, it is not, in that condition, being guided by the edge of the plate. Furthermore, if the pipe just touches the edge of the plate but there is no lateral force applied by the one to the other, again, in that condition, the pipe is not being guided. On the other hand, if the edge of the plate applies force to the side of the pipe so as to alter its direction, in that condition it is guiding.
  111. This issue was the subject of considerable evidence from Professor Witz. In his first report he said that he would interpret "means for guiding" to refer to any device:
  112. "which directs or diverts the angle [of the conduit] under conditions of average contact. By "average contact" I mean that the "flexible conduit" is in contact with it for the majority of the time. This element directs the angle of the "flexible conduit" into the angle of the catenary in the water column."
  113. Therefore the "last means for guiding the flexible conduit" as required by claim 3 would be the last device which directs or diverts the conduit under conditions of average contact.
  114. Professor Witz also referred to the fact that the Coflexip patent refers to the existence of a working table which may be put in place temporarily during pipelaying so that technicians can carry out work on the pipe. In relation to this he said:
  115. "The arrangement in the Patent may include a working table which may be opened or closed when the pipe is being laid. There may be occasions when the pipe comes into contact with the closed working table as a result of vessel motions but this does not mean the working table acts as a means for guiding, as it is not designed for average contact. This is clear from the Patent which refers to the linear tensioner as the last means for guiding the pipe. If the working table was designed for average contact, it would in my view be the last means for guiding the pipe." (Second Report paragraph 14)
  116. In the Stolt judgment it was held that the deflectors in the Seaway Falcon could not reasonably be called guides. It was said that they were no more guides than the bumpers at the front of a car or a crash helmet worn by a motorcyclist. Using the terminology of Professor Witz, the deflectors, bumpers and helmet are not designed for average contact. They are designed for an occasional contact outside the normal operating envelope of the vessel, car or motorcyclist, as the case may be.
  117. Professor Witz's analysis can be explained a bit further. The purpose of the guide means is to divert the pipe into its natural catenary below the pipelaying vessel. It applies a lateral force to the pipe. If one considers paragraphs 24 and 25 above again, a guide will react the horizontal tension in the pipe. In Claim 3 it is the winch-type tensioning means which must be the last means for guiding the conduit. That is to say, it is the tensioner which has to be the last piece of apparatus capable of reacting the horizontal tension in the conduit. As Mr Thorley points out, this is consistent with the passage on page 10 of the patent referred to in paragraph 53 above; it is the tensioner which ensures guidance of the conduit and a deviation relative to the vertical. This means that the tensioner has to be constructed in a way which allows it to react the horizontal tension in the conduit.
  118. This imposes some constructional constraints on the design of the tensioner. Not only must it be constructed in such a way that it is capable of withstanding the very considerable horizontal forces which it may encounter during normal pipelaying but also its outlet, that is to say the lowermost part of the tensioner (referred to as the "fore"), must be shaped so as to avoid damage to the conduit entering the sea. It will be recalled that one of the problems which exists when an accessory on a flexible conduit is overboarded under tension, is the risk of damage at the rigid/flexible junction (see Figure 7 above) Similar sorts of forces can act on the flexible conduit as it leaves the tensioner. This is illustrated by a drawing produced by Professor Witz in his First Report:
  119. Figure 14:
    Figure 14
  120. Construing the patent, save in relation to expressions having special technical meaning, is for the court. However, with one qualification, I think Professor Witz's analysis of these words in the claim is correct. He refers to "average contact" as meaning contact during the majority of pipelaying. It seems to me that a "means for guiding" is a part which is capable of applying that lateral force during a significant part of the operation of the pipelaying vessel within its normal operational envelope. For example a guide which would be in almost constant contact with the conduit during pipelaying in shallow water may not be in contact with it for much of the time when pipelaying in particularly deep water where the top of the catenary is practically vertical. Thus for the majority of the time in deep water the guide does not react the horizontal tension. It would nevertheless still be a guide means or means for guiding.
  121. Infringement

  122. As mentioned above, Coflexip only alleges infringement of the apparatus claims in the patent. For the purpose of this action, Rockwater produced a Process and Product Description together with a series of drawings. These are confidential. However the relevant design features of the Toisa Perseus are set out in the drawings of Rockwater's own patent application, UK 2,379,259. The general arrangement of the vessel is shown below:
  123. Figure 15:

    Figure 15
  124. Flexible conduit can be led from the reel (5), over a chute (6) and down through two vertical tensioners (8). The conduit passes out of the vessel through a moonpool (9). The design of the exit equipment is more clearly shown in the following drawing.
  125. Figure 16:

    Figure 16
  126. This shows the conduit (3) passing out of the bottom of the lower tensioner (8b). It is then illustrated passing through a clamp (11) which can be ignored for present purposes. The moonpool (9) has cover doors (13). On this is mounted a flared device (12) which is referred to as a pipe guide. This is designed to deflect the conduit through a small angle into the top of the conduit catenary. If the vessel is operating in very inclement weather, the conduit may be forced against the bottom outlet of the moonpool. To lessen the risk of damage to the conduit in such conditions, the outlet of the moonpool is curved (15). Before the conduit reaches the seabed, and assuming calm seas, it may pass through the centre of the flared device (12). However once the pipe reaches the seabed and a catenary is formed, the vessel must be driven in the pipelaying direction to avoid damage at the sagbend. When that takes place the conduit can engage the surface of the flared device (12). This is illustrated in the following drawing which shows the circular pipe (3) being pressed against the two walls of the flared device (12) on the left hand side:
  127. Figure 17:

    Figure 17
  128. The point to notice about this arrangement is that the lower tensioner (8b) is not designed to react the horizontal tension in the conduit. That tension is reacted on the surface of the flared device (12) and it is that device which then transfers the horizontal tension to the rest of the vessel. Mr Thorley says that the flared device (12) is a means for guiding the conduit. For this reason there can be no infringement of any of the apparatus claims in Coflexip's patent because in the Toisa Perseus the tensioners (8) do not comprise "the last means for guiding the flexible conduit". It should be made clear that no one suggests that the curved surfaces on the moonpool (15) are means for guiding. They are like the bumpers on the Seaway Falcon in the Stolt action. To apply the definition set out above, they are not capable of applying lateral force to the pipe during a significant part of the operation of the pipelaying vessel during its normal operational envelope.
  129. Mr Miller advances two types of argument to support the claim to infringement. First he says that the flared device (12) is not a "means for guiding" within claim 3. Alternatively he says that if it is a means for guiding, then, although this would mean that the tensioner is not the last such means, this feature of the claim can be ignored.
  130. Is the flared device (12) in the Toisa Perseus a "means for guiding"?

  131. Mr Miller says that the flared device (12) is not a "means" for guiding the pipe because it is not a wheel, gutter or chute or other device of the sort intended by the patent. For reasons set out above, I reject that argument. Alternatively he says that in the context of the laying operation in the Leadon and East Foinaven fields, it is not "for guiding" the conduit after the tensioner. He says that sometimes, for example when the conduit has not reached the seabed, the latter is hanging vertically and, in calm weather, will not be touching the device. At such times it is not guiding it and is not a means for guiding.
  132. I reject that argument too. The rear end of a stinger is a guide, as Mr Miller accepts, even though for much of its normal operation it is not in contact with the pipe. If the pipe is being laid in shallow water, the rear end of the stinger may never touch it. Nevertheless it is a means for guiding the pipe because it is capable of guiding during a significant part of the operation of the pipelaying vessel within its normal operational envelope. A means for guiding is not a means which is guiding. This is the same error as I made in the Stolt action when I held that "a device for operating the process" in claim 3 meant "a device which is operating the process". Furthermore, as Mr Thorley points out, Mr Miller's argument is self defeating. If one considers those instances when the pipe is hanging vertically, not only is the flared device (12) not applying any lateral force to the conduit, but neither are the vertically orientated tensioners because they also are not diverting the conduit from its vertical path. So, on this argument, they are not means for guiding either and the claim, which requires them to be the last means for guiding, is not met. In my view Mr Nash's evidence supports Rockwater's case:
  133. "185. During normal lay there will be an angle of lay which is dependent upon the submerged weight of the pipe, the depth of water and the bottom tension applied by the pull of the vessel. A lay angle of 1º-2º would be typical for the sizes of pipe and water depth of Foinaven. Vessels such as the Toisa Perseus can lay in the forward, sideways or reverse directions. The frequency of contact, and forces operating, between the pipe guide and the pipe will depend upon the direction of lay because the pipe guide is offset from the centre line of the tensioner. In the case of the Foinaven contract when laying in the forward direction, once a catenary is established, it is likely there would have been some contact between the pipe guide and the pipe but the extent to which the pipe was bent around the guide cannot be known for certain (because the angle of lay is not known for certain) although in normal circumstances it could be very small. If laying is taking place with the vessel moving in reverse then, under median conditions, the pipe would not contact the pipe guide up to an angle of lay of 1.2º (see table 6 below)." (First Report paragraph 185)
  134. This passage was the subject of cross-examination:
  135. "Q. … Let us get to the stage where we make contact with the seabed, which is paragraph 185 of your statement. As I understand it, you accept that in this state, with a lay angle of one to two degrees, there is likely to be some contact with the guide means, and that is [paragraph 185]. I just read it wrong. "... it is likely there would have been some contact between the pipe guide and the pipe but the extent to which the pipe was bent around the guide cannot be known for certain". A. Yes, that is right.
    Q. At that stage the horizontal tension due to the catenary will be taken on that pipe guide. A. Yes. Making the assumption that the vessel was going forward and you have an angle, yes, that is correct" (Transcript Day 4 page 525)
  136. On that evidence, in Foinaven, the flared chute (12) was not only capable of acting as a guide but, although not strictly relevant, it was guiding.
  137. The Improver argument

  138. There is something of an inconsistency in Mr Miller's final argument on infringement. Both in opening and in reply he made it clear that he was not asserting that this feature was an inessential integer in the claim. On the other hand he argues that, if the flared device (12) is a means for guiding the conduit, the Toisa Perseus still infringes. He says that the reference to the tensioner being "the last means for guiding" has to be construed in accordance with the Protocol on Article 69. He then relies on Aldous LJ's judgment in Wheatley v Drillsafe [2001] RPC 133 as indicating that the structured approach adopted in Improver v Remington Consumer Products [1990] FSR 181 assists in applying the Protocol and that a strict literal application of the claims is outlawed.
  139. Following a structured approach can be helpful. However it is not a straight-jacket. The court is trying to determine not what the inventor intended to be covered by his claims but the meaning of what he said he intended to cover. In doing that it can pay less regard to any wording used in the claim which appears to import a limitation which the skilled addressee would believe could not reasonably have been intended. The claims therefore have to be read in the context of the specification taking into account not only the words used but the explanation given by the patentee for how the invention is believed to work and what he states its benefits to be. In some cases where a party argues that he does not infringe because his apparatus or process omits a feature in the claim, the issue can be put simply as follows; would the notional skilled addressee who reads the whole patent understand that the particular feature in the claim has to be present. If that question is asked here, the answer is in the affirmative. Claim 3 only incorporates a few integers. This makes it less likely that any of them would be read as redundant. But, whether that is so or not, the passage on page 10 of the specification picks out for special mention the alleged originality of the feature that there are no means for guiding the conduit after the tensioner. The skilled addressee would not ignore this integer.
  140. The same conclusion is arrived at if one follows the Improver structured approach. First, does the incorporation of the flared device (12) in the Toisa Perseus have a material effect on the way the invention works? The answer to this requires an understanding of what the invention is said to be. The passage on page 10 of the specification points out the absence of a further downstream guide means that the tensioner "ensures guidance of the tubular flexible conduit". In other words the invention includes the alleged benefit of having a tensioner which not only applies vertical tension to the line but is capable of reacting horizontal tension for the purpose of guiding the conduit. The benefit of all the forces being able to be reacted by the tensioner is missing in the Toisa Perseus. The difference between the design of that vessel and the design in Coflexip's patent was explained by Professor Witz:
  141. "One of the consequences of using a linear tensioner as the last means of guiding (as in the Patent) is that the catenary top angle is directed or diverted over the fore of the tensioner from the vertical (see Fig [14] above ). In effect, the pipe is bent under tension over an arc at the fore of the linear tensioner. The associated bend radius is relatively small. It is generally undesirable to bend pipe at such relatively small radii under high tension, particularly for larger angles as this increases the risk of pipe collapse and wear and tear on the linear tensioner. An advantage of the pipe guide is that it has a radius which is larger than the radius of the fore of typical linear tensioners. This results in a reduced risk of collapse of the pipe, particularly at larger angles and alleviates the linear tensioner's components from the mechanical demands placed by the horizontal force." (Second Report paragraph 24)
  142. The third Improver question is; would the reader skilled in the art have understood from the language of the claim that strict compliance with the primary meaning was an essential requirement of the invention? As noted already, Mr Miller accepts that this feature of the claim is not inessential. In those circumstances it is difficult to see how the third Improver question can be answered in Coflexip's favour. In any event, the passage on page 10 of the specification would indicate to the skilled reader that the absence of any guide means downstream of the tension was an essential requirement of the invention.
  143. For these reasons, the allegation of infringement of claim 3 fails. Since all the other apparatus claims are dependent on this claim, all allegations of infringement fail also.
  144. Validity

  145. As mentioned above, Rockwater alleges that the claims in the patent are invalid on the grounds of anticipation and obviousness. At the commencement of the trial, three pieces of prior art were relied on, namely Recalde GB, Recalde US and UK Patent No. 1,059,932 ("IFP"). The latter relates to the opening and closing of the jaws of caterpillar tensioners. As a result of the oral evidence given by Mr Nash in relation to how such tensioners were normally used, Mr Thorley decided that he no longer needed to rely on this piece of prior art.
  146. The Prior Art

  147. Although Recalde US and Recalde GB are equivalents and contain much common information, there are some differences which are said to be material to the issues in this case. For that reason it is necessary to consider them separately. The parties concentrated most of their attention on Recalde US and I will do likewise. Before considering this material, it is worth mentioning a preliminary matter. There is a dispute between Coflexip and Rockwater as to what each of the prior art patents discloses. In support of their respective constructions they served evidence, Coflexip relying on Mr Nash's interpretation and Rockwater relying on Professor Witz's. However, in relation to those passages in the specifications where the parties are in disagreement, there are no disputed terms of art. The disputes therefore relate to the construction of passages in the documents which are non technical and use ordinary English words and grammar. I understand Mr Miller and Mr Thorley to agree that that is so. In the circumstances it appeared to me that much of the evidence was inadmissible. Mr Miller and Mr Thorley agree that the construction of the prior art is a matter for the court alone. They agree that I am not constrained by anything the witnesses say, but they also agree that the evidence allows each side a convenient avenue by which to put its case on construction before the court. Each side also criticizes the other's expert. Mr Thorley says that Mr Nash has been steeped in the litigation concerning the patent in suit for such a long time that, no doubt subconsciously, he has interpreted the prior art in a way which is most favourable to Coflexip. It is suggested that he has done this to the extent of ignoring or misreading the clear wording of the documents. Mr Miller argues that Professor Witz read the Recalde specifications knowing the points in dispute between the parties. As a result, again subconsciously, he has resolved alleged obscurities in the text in a manner which suits Rockwater. Having seen both these experts in the witness box, there is no reason to doubt the sincerity of the views they have expressed.
  148. Normally, it would be appropriate to reject this type of evidence out of hand. But I agree with Counsel that in this case it has served a useful purpose. Professor Witz said that it took him about two days to read Recalde US. I am not surprised. Although it is not suggested that there are any complex concepts discussed in these documents, each of them is crammed full of information. This makes for a difficult and, frankly, turgid read. Much of what is disclosed has no or only peripheral relevance to the issues in this trial. Those passages which are or may be relevant are scattered throughout the text. Digesting the disclosures is a considerable task. As Counsel say, each expert has put into writing his side's interpretation of the document. By doing so, the task of understanding not only the documents but also the arguments between the parties has been eased. Nevertheless, ultimately construction of the prior art is not a matter for the experts. The expert evidence directed to these prior art documents is also admissible in so far as it relates to the issue of obviousness.
  149. In the following analysis of the Recalde patents, I refer to some of their drawings. They are annexed to this judgment. To aid comprehension, in some cases I have coloured the particularly significant components and have removed the numbers and lead lines which refer to components which are of no relevance to the issues. This has not altered in any way the structure of the Recalde apparatus. It has simply made it possible to understand the drawings without the distraction of references to irrelevant material. The letter "p" at the end of a number indicating a particular part indicates that that part is on the port side of the vessel, e.g. 330p. The letter "s" similarly indicates starboard side, e.g. 330s. The letter "a" indicates aft and "f" indicates fore.
  150. The disclosure in Recalde US

  151. This patent describes apparatus for, and methods of laying, a number of submarine pipes and other conduits simultaneously. It refers to a variety of prior proposals for laying rigid pipes in deep water including rigid pipe which has been spooled onto a reel. It refers to prior art which discloses the use of a combined straightener-level winder to spool the rigid pipe onto the reel and for straightening it as it is unspooled. In passages dealing with the prior art it also contains a section which concentrates on the design of the Apache in which spooled rigid pipe was fed down a ramp at an acute angle to the sea (i.e. using a J-Lay configuration). It goes on to note that the Apache was not equipped to layout multiple lines, apparently because it had a single main reel (for rigid pipe) and insufficient deck space for convenient placement of auxiliary reels. It comments that there was an early suggestion during the Apache's construction phase to mount portable reels on its desk to permit smaller lines to be bundled with the pipeline (that is to say put together with and connected to the rigid pipe) at the stern of the vessel. It notes:
  152. "These smaller lines were not required to be passed through the pipe handling equipment with the main reel pipeline according to the suggestion …" (Column 3 lines 58 to 60)
  153. In a section entitled "Summary of the Invention", Recalde US points to the increasing requirement in the offshore petroleum industry for laying multiple operational lines in water more than 3,000 ft deep. The expression "operational lines" is used throughout the specification as a generic term to include rigid and non-rigid pipes and other types of conduits. For example it includes not only rigid pipes but also electrical cables and tension support cables (Column 11 lines 50 to 57). It is not in dispute that this encompasses the type of flexible conduit referred to in Coflexip's patent. Recalde US goes on to say:
  154. "To be commercially viable a pipelaying vessel must also be capable of laying either single or multiple operational lines in shallow waters of less than 200 ft. up to 3,000 ft. depth." (Column 4 lines 2 to 5)
  155. The summary of the main objective of the patent reads as follows:
  156. "A principal feature of the present multi-reel pipelaying vessel is that an operational lines laying device is mounted adjacent to the stern of the vessel. A plurality of operational lines are unspooled from the reels mounted on the vessel and are laid out into simultaneous contact with the laying device which includes an operational lines supporting means adapted for providing moving contact with the operational lines. The preferred laying device of the present invention changes the direction of movement of the plurality of operational lines from horizontal to vertical and can be used for laying operational lines in shallow waters of under 200 ft down too much greater depths of 7,500 ft and beyond. The supporting means is adapted for gathering the operational lines into an initial juxtaposed configuration which is parallel with the direction of forward vessel motion. All of the operational lines are moved at the same linear velocity due to the contact thereof with the supporting means of the operational lines laying device.
    The preferred operational lines laying device also includes straightening and tensioning devices which are adapted to straighten and provide tension for the operational lines while maintaining the same in a juxtaposed array which is aligned with the direction of forward vessel motion. The straightening means is adapted for imparting a reverse bending force to the rigid walled pipeline(s) which are among the operational lines being laid out." (Col 4 lines 16 to 44)
  157. The general layout of the equipment can be best understood by reference to Annex 1 to this judgment which contains drawings derived from Figures 1 and 4 of the patent. The top drawing is a schematic view of the multi-reel vessel and the bottom drawing is a larger scale version of the stern half of that vessel. Towards the centre of the vessel there is a main reel (20 – red) which is adapted to provide storage for a series of wraps of rigid walled pipeline. The drawings show a single pipeline (22) being unspooled from that onto the pipe takeoff assembly (shown generally at 24 – orange and dark blue). This pipe takeoff assembly includes a pipe take-off drum (26 – dark blue) which is located over the stern of the vessel. The pipe take-off assembly also includes a pipe take-off structure (30 – orange). The pipe take-off structure incorporates a straightening device (32) and a tensioning device (34). The designs of the latter devices are not clearly depicted in these drawings. They will be discussed below by reference to other Annexes. Next to the main reel (20) there is a first auxiliary reel (36 – green). Next to that is a second auxiliary reel (40 – yellow). Operational lines (44 and 46) are taken off these reels and over the pipe take-off drum (26) side by side with the pipe (22) from the main reel (20). As Recalde US explains:
  158. "All of these operational lines are gathered together into an initial horizontal juxtaposed configuration at the top of the take-off drum 26 and are maintained in continuous contact with the periphery thereof as the direction of movement of these operational lines is changed from horizontal to vertical at the stern end of the pipe take-off drum 26.
    The contact between the operational lines 22, 44 and 46 with the periphery of the pipe take-off drum 26 results in the linear velocity of layout of all of these lines being equal. Upon changing of the direction of movement from horizontal to any angular pipe take-off position the operational lines are then passed through the straightening means 32 and the tensioning device 34 so that the array of these lines passes downwardly over the stern 28 at nearly a 90o angle as shown in FIG 1 for deep water layout." (Col. 10 lines 13 to 30)
  159. It should be noted that in this passage and throughout the specification the group of operational lines being laid simultaneously is referred to as an "array". The pipe take-off drum rotates round an axle (116). The pipe take-off structure (30) is constructed integrally with a support frame structure (114). This is mounted on the same axle (116). This is connected to motors which enable the pipe take-off structure (30) to rotate so as to accommodate different angles at which the array (35) enters the water. The vessel also includes winches. One of these is shown beside the main reel (20) on the upper drawing in Annex 1. The arrangement consists of a storage reel (50). On it are stored two cables (52, 54). These pass under the main reel (20) by way of a twin groove sheave (56) and rollers (58, 60) to a twin drum traction winch (62).
  160. The internal structure of one version of the pipe take-off structure (30) is shown in Annex 2. This is based on Figure 8 of Recalde US. This illustrates the passage of an array of pipes and conduits (35 - light blue) into the top of the pipe take-off assembly past the straightening device (32 - yellow), between the co-operating caterpillars of the tensioning device (34 - green and pink) and through an opening, called the operational line array opening, (368) down towards the sea.
  161. Considering first the straightening device (32), this consists of a first track assembly (102) made up of a main carriage (308) at either end of which is a sprocket gear wheel (318, 320) which carries an idler roller assembly (328). The idler rollers and guide rollers (310p) force a flexible chain into engagement with the surface of the operational line array (35). Behind the main carriage (308) is an internal guide frame (280p) in the middle of which is a hydraulic positioning ram (306p - mauve) with a hydraulic ram piston (316). The function of this ram is to force the face of the straightening device towards or away from the operational line array (35) as designated by the arrows S1. The straightening device (32) is also articulated which allows it to pivot as indicated by the arrows S2.
  162. The operational line array (35) then passes into the tensioning device (34). On one side is the second track assembly (104 - green). This consists of a carriage at either end of which are motors (348, 346) which engage and drive a flexible chain rack (349). Behind this track assembly is an internal guide frame (287p) in the middle of which is a hydraulic ram (330p) which acts through a piston to force the track assembly towards or away from the operational line array (35). On the opposite side of the operational line array (35) is the third track assembly (106 – pink). This has a structure which is the same as the second track assembly (104) save that its hydraulic ram (338p) is somewhat shorter. On the seaboard side of the tensioning device (34), the operational line array (35) passes through the opening (368). In the region of this opening, there is a retractable clamp (367 - red). This can be operated to lock the operational line array (35) in position, for example if work has to be done on the array. During normal pipelaying it is retracted. In this region there is also a pipe aligner clamp set (370 - brown) which can be used to manipulate the array when it is locked by the clamp (367). There are also pivotally adjustable floor panels (358, 356) on which workers can stand for the purpose of manipulating the array. Finally there is an A&R (i.e. abandonment and recovery) winch (362 – orange).
  163. In Annex 3, the top drawing is of a cross section of the straightener (32) depicted in Annex 2. Its function is to plastically deform the bent pipe which is being carried to it on the outer rim of the pipe take-off drum (26 – blue) which can be seen in Annexes 1 and 2. To do this, the pipe has to be clamped between a pipe-receiving surface (brown) on the pipe take-off drum and support pads (green) carried on flexible chain racks (322). In the illustrated embodiment there are openings for 6 pipes or conduits between the drum and the support pads. They are grouped into three pairs. The flexible chain rack carrying each pair of pads can be moved towards and away from the take-off drum (26) by means of manually-operated jactuator adjusters (329 – red). The composite component carrying the flexible chain racks, jactuator adjustors and pipe-supporting pads can be moved forwards or backwards by actuation of hydraulic positioning rams (306p and 306smauve). The latter forward and backward movement is facilitated by guide rollers (310p and 310s) which run in lateral tracks. The positioning rams (306p and 306s) are mounted on ears (314p and 314s) which allow the mechanism to pivot. It will be noticed that the straightener contains no drive means. The rigid pipe which is to be bent has to be drawn round the take-off drum and through the straightener. Depending on the dimensions and construction of the pipe, this takes considerable force.
  164. The tensioner device is shown in cross-section in the bottom drawing. It consists of two co-operating track assemblies (104 and 106) which can be forced towards or away from each other by the hydraulic rams (330p, 330s, 388p and 338smauve). This movement is facilitated by guide rollers (336p, 336s, 342p, 342s) carried on the outer surfaces of the track assemblies which co-operate with tracks. The second track assembly (104) includes hydraulic motors on each side (348p, 348s). With the assistance of an idler roller assembly (352), these motors drive flexible chain tracks (349). On either side of the track assembly (104) there are adjustment cylinders (353p and 353s) which permit variation in the applied force for the idler roller assemblies. The second and third track assemblies (104, 106) carry opposing operational lines supporting pads pairs (354ared and 354fgreen). The way in which the tensioner is intended to work, the subject of considerable dispute during the trial, will be considered below. It should be noticed that in this embodiment, there is a single supporting pad on each track assembly (104, 106). That is to say, the 6 pipes or conduits are caught between two opposing pads, each pad having 6 indentations in its surface to accommodate the pipes or conduits.
  165. Recalde US also discloses an alternative design for the straightener and tensioners of Annex 2. These are described by reference to three drawings, Figures 17 to 19 in the patent. Annex 4 contains drawings based on those Figures. The description of these drawings in the specification commences with the following:
  166. "A preferred configuration of a straightener/tensioner track assembly which can be used for assembly 102 and, with some modification to provide for adequate hydraulic power, also for assemblies 104 and 106 is shown in FIGS. 17 – 19." (Col 19 lines 29 to 33)
  167. Thus, subject only to the need for adequate hydraulics, the design depicted can be used either for the straightener or the tensioners. The top drawing is a side elevation of the preferred device, the middle drawing is a transverse cross-section and the bottom drawing is a vertical section taken along the lines 19 – 19 of the top drawing. The device carries three endless tracks (322 – light green) on which are mounted support pads (624, 626, 628, 630, 632 and 634 – yellow). Each such pad is designed to interface with up to two pipes or conduits. This can be seen particularly clearly in the bottom drawing. Each endless track is mounted on a pair of sprocket gears (540/544, 539/543 and 538/542 – lilac). These sprocket gears are attached to axles (534, 536 – dark blue) which are carried in axle housings (546, 556, 558 and 560 – turquoise) which can slide inside C-shaped brackets (554 and 556 – dark green). The axles (534, 536) can be pushed away from each other by means of hydraulic rams (550, 552, 562, 564 – light mauve) which act on the axle housings (546, 556). Sprocket chain tension gears (324, 326 – grey) bear against the back of the tracks so as to maintain the tracks in tension. Each of the three tracks is mounted over a row of nine idler rollers (602, 604, 606 – dark pink). Each idler roller is carried on a mounting frame (612 – beige) which is connected to one end of an adjusting screw (614 – red). The other end of each adjusting screw passes through a jactuator (616 – pink) which can be operated manually to move the mounting frame with associated idler roller forward or backwards. As depicted in the bottom drawing, the jactuators are adjusted so as to accommodate the different outside diameters of the pipes or conduits in the operational lines array. Finally, the whole device can be moved forwards or backwards (as depicted in Annex 2) by the operation of hydraulic rams which are connected to it (317p, 317smauve).
  168. In the embodiment of Recalde US depicted in Annexes 1, 2, 3 and 4, the tensioner and straightener are shown as discrete pieces of equipment. However the patent also discloses another embodiment in which one device carries out both the tensioning and straightening functions. This is said to be the preferred form of apparatus with respect to operating efficiency and capital cost minimization. This is illustrated in Annexes 5 and 6 which are derived from Figures 36, 37 and 38 of the patent. Annex 5 has two drawings on it. The top one is a side elevation. The bottom one is a cross-section taken on the lines 37 – 37 of the top drawing. Annex 6 contains a more detailed view of the interacting caterpillar mechanisms of the straightener/tensioner. It will be appreciated that many of the features of this device are similar to those illustrated in Annex 4.
  169. Considering the top drawing in Annex 5 first, this shows the operational line array (light blue) entering from top right and exiting bottom left. It enters the straightener/tensioner multiple track assemblies (1020 and 1022 – respectively green and pink). These are equipped with multiline tracks (1042 and 1044). The straightener/tensioner multiple track assemblies can be pushed towards or away from each other by operation of the hydraulic rams (1034, 1036 – mauve). The straightener/tensioner multiple track assemblies contain a number of hydraulic motors (1046s, 1048s, 1050s and 1052s [there will also be four motors on the port side]) to drive the multiline tracks. The locations marked A, B and C identify zones where force is applied to straighten any rigid pipe entering the straightener/tensioner device which needs straightening.
  170. The cross-section drawing in the bottom half of Annex 5 shows the same parts identified by the same numbers. However this drawing also shows the pipe/conduit retaining pads (respectively yellow and green) on the left and right chain track sets (1042 and 1044). The individual pipes and conduits are located between opposing pads. The drawing also depicts the adjusting screws and jactuators (red) which were identified (614, 616) in the top drawing in Annex 3 and Annex 4 as part of the tensioner device.
  171. A more detailed view of the combined straightener/tensioner is to be seen in Annex 6 which is a view from the side. This depicts the operational lines array (35 – light blue) entering between the opposing chain track sets (1042, 1044 – respectively yellow and green). Once again, the opposing hydraulic rams (1034s, 1036smauve) are shown. The hydraulic motors (1046s, 1048s, 1050s, 1052sgrey) are shown. The individual adjusting screws (red) which can be adjusted to press down on the chain track sets (1042, 1044 – respectively yellow and green) are inside the straightener/tensioners. However there are sight openings (1104, 1106) in the walls of the apparatus through which it is possible to observe the rotation of the jactuator screws, which are used to adjust the setting of each adjusting screw. The only other part of this adjustment mechanism which can be seen from the side is the bottom part of the idler rollers at the point where they face each other on either side of the pipeline array (35). On the left-hand device in the drawing, the outline of the jactuator/adjusting screw mechanisms inside are represented in ghost outline (pink). The drawing also illustrates a series of jactuator adjustment openings (1100, 1102 – brown). Recalde US explains that:
  172. "These jactuators adjustments permit the turning of internally mounted screws in order to position the multiple roller guides independently." (Col. 30 lines 1 to 4)
  173. Annex 6 shows that there are nine roller guides (red) on either side of the operational line array (35). The bottom drawing also shows that there are three endless chain track sets on each caterpillar straightening/tensioning device, that is to say, the tracks for the top two small conduits, the track for the middle two large conduits and the track for the bottom two small conduits. Recalde US explains:
  174. "As shown in FIG 38[2] nine roller guide sets are provided for each of three endless sprocket chains which are employed to support the pipe pads for three pairs of lines which constitute the pipeline array 35 as shown in FIGS 37[3] and 38." (Col. 30 lines 4 to 8).

    How does Recalde US work?

  175. It will be appreciated that if one of the auxiliary reels (36, 40) in Annex 1 is loaded with a flexible conduit, as Recalde US teaches, that conduit passes over the take-off drum 26, which is a form of sheave, and down to the water through the tensioner (34). This arrangement is the same as that depicted schematically in Figure 13 above. In other words the major items of hardware required by claims 1 and 3 of the patent in suit are present. Major issues between the parties concern the meaning of Recalde US's description of the operation of the apparatus and how the apparatus can be operated. Coflexip's case is that virtually all the axial tension is taken on the reels (20, 36 and 40). The teaching of the specification is that flexible conduit passing through the straightening/tensioning section with the rest of the operational lines array (35) would only be in touching contact (if in contact at all) with the tensioner, so that no part of the axial load in the conduit would be taken by the tensioner and that the apparatus is of a design which would not allow the tensioners to take up the axial load of the flexible conduit. Rockwater argues that the tensioner (34) takes all or most of the axial tension in the flexible conduit and that, even if that is not described, the apparatus is capable of being operated in that way.
  176. As mentioned above, the description in Recalde US is detailed. The passages which throw light on the issues to be decided in this action are distributed throughout the specification. It is necessary to gather them together to understand how pipelaying is achieved and, in particular, how the tensioner at the rear of the vessel operates. It must also be borne in mind that the specification describes more than one method of operation.
  177. Coflexip argues that this patent is primarily concerned with laying rigid spooled pipe. For that reason it needs to have a straightener. The tensioner co-operates with the straightener, or is incorporated within it, to assist in the removal of the curve from the rigid pipe. The result is that although flexible conduits take the same route as the rigid pipe(s) in the operational lines array (35) over the take-off drum (26) and down through the straightener (32) and tensioner (34) into the water, there is no need for them to be straightened, because they are not plastically deformed in the first place. Therefore their passage through the straightener is essentially passive. They are in contact with the straightener but have no force applied to them by it. Since this is so, there is also no need for the tensioners to apply tension to them for the purpose of reacting the tension created by the line hanging below the vessel. The flexible conduits may, but need not, contact the pads on the tensioner, but that is all. Mr Nash summarised the point:
  178. "There is no technical reason why Recalde US would wish to have the tensioners grasp the operational lines which are not rigid pipes." (First report paragraph 153).
  179. It is true that a major objective of Recalde US is to provide for the straightening and laying of rigid pipe and it is for that reason that the straightening facility is present. In all the described embodiments of the invention, the operational line array must include at least one rigid pipe (see, for example, Col 6 lines 2 to 6, and lines 58 to 62). The existence and use of the straightener and tensioner are central to the patent. Furthermore all of the reels described and illustrated are powered. The reason for this is explained:
  180. "The storage reels are fitted with hydraulic motors for imparting motive power to the reel flanges or rims in order to provide for spooling up of the lines. The hydraulic motors are also fitted with hydraulic braking systems for controlling tension of the lines during unspooling and to control the rate of line(s) layout." (Col. 6 lines 17 to 23)
  181. Thus, these motors can be used to pull pipe onto each of the reels while they are being loaded ("spooling up"). Furthermore there are provisions to apply a brake to each of the reels during pipelaying ("unspooling"). This means that the braking system can be used to oppose or react the tension created by the pipe suspended under the vessel. Furthermore there is an indication in the patent of how powerful the motors or brakes on the reels are expected to be:
  182. "In deep waters beyond 3,000 ft the weight of the pipeline(s) is sufficient to elastically straightening the rigid walled pipe. In this embodiment it is possible to use the hydraulic braking systems on the operational lines reel motors to provide tensioning of the lines, thus permitting pipe layout in the absence of separate straightening and/or tensioning devices." (Col 5 lines 3 to 9)
  183. In this embodiment, the totality of the tension generated by the suspended pipe in the deepest water can be reacted by the braking system on the reels. The specification therefore teaches the design of equipment in which all or substantially all of the tension is capable of being taken by the reels upstream of the take-off drum. When operated in that mode, the equipment is being used in the manner indicated in Figures 4 and 5 above. Although this embodiment illustrates the intended versatility of the Recalde design, it is an embodiment which eschews use of the straightener and tensioner and is therefore somewhat peripheral to the main teaching of the patent. On the other hand it should be noticed that this passage states that in deep water the rigid pipe can be straightened without using the straightening and/or tensioning devices. It could be said that this means that in some embodiments, the straightening device is still used but the tensioning device is not and that, in such a case, it is the tension generated by the weight of suspended pipe which renders the tensioner redundant. In other words, the tension which had been applied by the tensioner is now applied by the weight of suspended pipe. If this is what the passage means, the tensioner (prior to its redundancy) was pulling in a seawards direction, not towards the vessel and, for that reason, again all the tension (save for that necessary to force the rigid pipe through the straightener) is taken on the reels. However, even if so, this does not affect the general teaching of Recalde US which is considered below. The parties agree that caterpillar tensioners are normally reversible. This means that the tensioners shown in this patent can either pull towards or away from the seabed. The last above cited passage may indicate that sometimes the tensioner pulls towards the sea. In any event, it is likely that when laying commences, the operational lines array will have to be fed through the straightener and tensioner. Since, at the very beginning of this operation, there will be no weight of suspended pipe to help pull the array through and to overcome the resistance generated by the straightener, it is likely that the tensioner will be used to pull in a seaward direction.
  184. Notwithstanding the above, the important questions are (i) what does Recalde US teach about the way in which its apparatus operates during normal pipelaying and, (ii) of particular significance to Claim 3 of Coflexip's patent, how can the apparatus be operated?
  185. In my view Recalde US teaches that all the lines in the array, including the flexible conduits, are grasped by the tensioner and have axial tension in an upward direction applied to them by it. Further it teaches that most, if not all, of the tension generated by the suspended pipe can be reacted or taken by the tensioner. If that is so, little axial tension exists in the operational lines array passing over the take-off drum. Set out below are the passages in the specification which appear to support that conclusion. It should be borne in mind that the expressions "array" and "operational lines array" are used throughout the specification to designate all the pipes and conduits which are being laid simultaneously.
  186. A convenient starting point is the summary of the invention which commences on column 3 of Recalde US. It is worth repeating one passage which has already been set out earlier in this judgment:
  187. "The preferred operational lines laying device also includes straightening and tensioning devices which are adapted to straighten and provide tension for the operational lines while maintaining the same in a juxtaposed array which is aligned with the direction of forward vessel motion. The straightening means is adapted for imparting a reverse bending force to the rigid walled pipeline(s) which are among the operational lines being laid out." (Col 4 lines 36 to 44)
  188. There is no dispute that the straightener only operates on the rigid pipes since they are the only ones which need to be bent back to the straight configuration. The above passage points out that the straightener works on the rigid pipes. However it also says that the tensioning device is adapted to provide tension to the operational lines array. The natural meaning of this is that the tensioner applies tension to each of the lines in the array, including any flexible ones. Coflexip's argument, as expressed by Mr Nash, is that the flexible lines or conduits are neither tensioned nor straightened. If that were so, this paragraph would have been directed to rigid pipes alone rather than all the lines in the array.
  189. The next significant passage is as follows:
  190. "The tensioning device 34 is formed by a second track assembly 104 and a third track assembly 106 which act on opposite sides of the operational line array 35, respectively, in order to provide tension for supporting the pipeline weight which is suspended from the pipe take-off assembly 24." (11-1, 11-8)
  191. There is no dispute that this passage indicates that the tensioner is exerting a force in the upwards direction away from the seabed. Mr Thorley argues that the reference to providing "tension for supporting the pipeline weight" indicates that substantially all the tension is reacted by the tensioner with the consequence that upstream of the tensioner there is little or no tension. I do not accept that argument. Taken by itself, the passage could just as well mean that the tensioner provides tension to assist in the support of the weight of the suspended pipes. On the other hand Mr Miller argues that this passage only refers to supporting "the pipeline" and this must be a reference to the rigid pipeline. I do not accept that argument either. Both on its own and in the context of other passages to which reference will be made below, this suggests that all the lines in the ar