Patent Description:
Traditionally, flexible pipe is utilised to transport production fluids, such as oil and/or gas and/or water, from one location to another. Flexible pipe is particularly useful in connecting a subsea location to a further subsea location or a sea level location. Flexible pipe is generally formed as an assembly of a segment of flexible pipe body and one or more end fittings in which respective ends of the flexible pipe body are terminated. The pipe body is typically formed as a composite of tubular layers of material that form a fluid and pressure containing conduit. The pipe structure allows large deflections without causing bending stresses that impair the pipe's functionality over a desired lifetime. The pipe body is generally, but not necessarily, built up as a composite structure including metallic and polymer layers. Flexible pipe may be utilised as a flowline overland and/or at a subsea location. Flexible pipe may also be used as a jumper or riser.

It is known that when flexible pipes are designed the environmental factors which the flexible pipe is to experience over its service life are taken into account so that the flexible pipe hopefully functions in use without failure. A typical service lifetime is twenty years or more and some flexible pipes are utilised in deep or indeed ultra-deep water conditions where many kilometres of overlying seawater can be expected to continually apply a high pressure crushing force on an external part of flexible pipe body or an end fitting. Such high pressures can easily reach <NUM> kPa (<NUM> psi) or more.

Likewise an internal bore in a flexible pipe which is used to transport production fluids can continuously experience very high pressures of up to more than <NUM> kPa (<NUM>,<NUM> psi) or more. These considerable pressures, and the timeframes over which such pressures must be withstood, mean that designing and manufacturing flexible pipe involves the use of materials and manufacturing processes which are complex and costly to implement.

Still furthermore because flexible pipes are difficult to replace after being installed at a subsea location, any design of a flexible pipe usually involves an overestimation of environmental conditions which could be experienced by the flexible pipe. Effectively considerable in-built redundancy must be designed in to minimise risk of failure. Detailed and rigorous testing procedures are in place which must be qualified by any flexible pipe prior to being put in service. For example API standard 17J (ISO <NUM>-<NUM>) defines a design pressure which is a maximum internal pressure expected to be experienced by a flexible pipe. A factory acceptance test (FAT) which must be passed by a flexible pipe requires that a test pressure of <NUM> x this design pressure must be applied to a flexible pipe during testing after manufacture to test for latent defects. It is noted that the <NUM> x design pressure threshold is allocated for flexible pipes destined to be used as flexible risers and topside jumpers whilst <NUM> x the design pressure is specified for flexible flowlines and subsea jumpers. In any event the <NUM> or <NUM> x factor when applied to pressures which are already expected to be considerable means that testing pressures applied to flexible pipe during qualification can be very significant and as a result very costly and complex design and manufacturing is needed to create a pipe that will pass such tests.

It is also known that during manufacturing of a particular flexible pipe seal rings are utilised in an end fitting to help terminate an end of the flexible pipe body of that pipe. During manufacture from time to time it is desirable to be able to test to see if successful sealing has been achieved when the sealing elements are energised or thereafter. Conventional testing methods are complex and prone to user error and can require bespoke test ports and test passageways to be included in a design which become redundant subsequent to testing.

It is also known that from time to time flexible pipes are manufactured which are not immediately put into service but can instead be stored for some time prior to installation at a desired location. Sometimes the length of time of such storage can be a few months or even years. Subsequent to a period of storage it is preferable (and in some cases essential) to be able to test whether any failure of any sealing mechanisms has occurred during storage. This is preferable to putting the pipe in service and then finding out about a failure. Conventionally there has been little or no solution to this other than putting the flexible pipe into service and monitoring for failure or alternatively running a complicated hydro test process. This can of course be a costly and time consuming process to rectify if a failure occurs.

<CIT> discloses a method and apparatus for testing the integrity of a portion of flexible pipe body.

It is an aim of the present invention to at least partly mitigate the above-mentioned problems.

It is an aim of certain embodiments of the present invention to provide a way in which a design differential pressure can be utilised during a design process for a flexible pipe.

It is an aim of certain embodiments of the present invention to enable a smaller and lighter structure of a flexible pipe and end fitting to be provided for any given internal design pressure.

It is an aim of certain embodiments of the present invention to provide a flexible pipe in which at least one pressure resistant fluid communication passageway is constantly provided between at least one external port which experiences local high hydrostatic or test pressure and a location or multiple locations between spaced apart seals in an end fitting.

It in an aim of certain embodiments of the present invention to provide a method of transporting production fluids in which a local hydrostatic or test pressure can constantly be communicated between key structural elements of an end fitting and flexible pipe located at a subsea location.

It is an aim of certain embodiments of the present invention to provide a method and apparatus for communicating a high local hydrostatic pressure to an internal region of an end fitting as desired and to automatically release high pressure at an internal location of an end fitting whilst the end fitting is submerged in a body of seawater as the end fitting is lifted towards the surface of the body of seawater.

According to a first aspect of the present invention there is provided an end fitting for a flexible pipe for transporting production fluids, comprising:.

Aptly said external port is located to receive a local hydrostatic pressure in use when an end of a segment of flexible pipe body is terminated in the end fitting and submerged in a body of seawater.

Aptly the passageway comprises a bore through the end fitting body between the outer and inner ports.

Aptly the passageway comprises at least one lumen connected between a first bore in the end fitting body, extending between a first lumen end and the inner port, and a further bore in the end fitting body extending between a further lumen end and the external port.

Aptly the lumen is at least partially filled with a pressure communicating fluid.

Aptly the communicating fluid is a grease or hydraulic oil.

Aptly the lumen is a metal pressure resistant tube.

Aptly the tube is pressure resistant to about around <NUM> kPa (<NUM> psi) or more.

Aptly the external port comprises a gas vent port.

Aptly the external port comprises a filter element.

Aptly the external port is always open to constantly communicate local hydrostatic pressure to the inner port.

Aptly said at least one external port, at least one corresponding inner port and corresponding fluid communication passageway, comprises:.

Aptly the end fitting further comprises:.

Aptly the end fitting further comprises:
a plurality of seal ring elements for sealing against at least one internal fluid retaining layer of the flexible pipe body.

According to a second aspect of the present invention there is provided a flexible pipe for transporting production fluids, comprising:.

Aptly the fluid communication passageway comprises a lumen having pressure resistant walls for communicating pressure up to about around <NUM> kPa (<NUM> psi) or more to or from said a location.

Aptly the at least one internal fluid retaining layer is a barrier layer or liner of the flexible pipe body.

Aptly the at least one internal fluid retaining layer is an intermediate layer between a barrier layer or liner and an outer sheath of the flexible pipe body.

Aptly the at least one internal fluid retaining layer comprises a barrier layer or liner and an intermediate layer configured between the barrier layer or liner and an outer sheath of the flexible pipe body.

Aptly each seal element is an annular seal ring having a cross-section comprising a seal ring body and a sealing lip extending from the seal ring body.

Aptly the seal rings are arranged in a spaced apart coaxial and commonly facing configuration.

Aptly each seal element is a sealing lip extending in opposed directions in a back-to-back relationship from a shared body region of an annular seal ring.

Aptly the flexible pipe further comprises a respective valve for selectively opening and closing each external port.

Aptly each valve comprises an always open valve.

Aptly the at least one external port and corresponding fluid communication passageway further comprises:.

Aptly the flexible pipe further comprises:.

Aptly the flexible pipe further comprises:
a pressure communicating material at least partially filling at least one fluid communication passageway.

According to a third aspect of the present invention there is provided a method of testing at least one seal in an end fitting, as described in the first aspect of the invention, of a flexible pipe, comprising the steps of:.

Aptly the method further comprises testing seal integrity of a seal provided by said seal elements during onshore storage of the flexible pipe.

Aptly the method further comprises testing seal integrity of a seal provided by said seal elements immediately subsequent to completion of end fitting assembly.

Aptly the method further comprises simultaneously testing seal integrity of a primary seal ring and a secondary seal ring, respectively comprising the spaced apart seal elements, sealed against a common internal layer or different internal layers of the flexible pipe.

Aptly the method further comprises applying the test pressure by providing a test fluid at a test pressure, from a test fluid source, at said external port.

Aptly the method further comprises, subsequent to the application of a test pressure, monitoring pressure at said external port over a pre-determined period of time.

Aptly the method further comprises applying the test pressure to said a location via at least one inlet valve of an external inlet port of the end fitting.

Aptly the method further comprises subsequently releasing test pressure from said a location via at least one exit valve of an external exit port of the end fitting.

Also disclosed is a method of transporting production fluids via a flexible pipe, comprising the steps of:
during transport of production fluids along an inner bore of a flexible pipe defined by an inner fluid retaining layer, continually communicating a local hydrostatic pressure to a location between a pair of spaced apart seal elements sealed against a radially outer surface of the inner fluid retaining layer and/or a location between a pair of spaced apart seal elements sealed against a radially outer surface of an intermediate fluid retaining layer disposed between the inner fluid retaining layer and an outer sheath layer.

Also disclosed is a method of transporting production fluids via a flexible pipe, comprising the steps of:
during transport of production fluids along an inner bore of a flexible pipe defined by an inner fluid retaining layer, continually communicating a local hydrostatic pressure to a location between a pair of spaced apart seal elements respectively sealed against a radially outer surface of the inner fluid retaining layer and against a radially outer surface of a radially outer polymer layer disposed between the inner fluid retaining layer and an outer sheath layer respectively.

Aptly the method further comprises the steps of:
communicating the local hydrostatic pressure by applying the hydrostatic pressure via a body of seawater to an external port of an end fitting of the flexible pipe; and communicating the local hydrostatic pressure from the external port to said a location via a fluid communication passageway that is pressure resistant to at least about around <NUM> psi.

Certain embodiments of the present invention enable a differential pressure approach to be taken when a flexible pipe is designed and manufactured for submerged applications. This can be used to specify the structural design of a flexible pipe (i.e. the difference between the external pressure and the internal pressure is used to calculate a net force acting on the pipe structure).

For deep and ultra deep water applications where a significant external hydrostatic pressure is expected this approach can allow a smaller, lighter structure to be provided for any given internal design pressure than would otherwise conventionally be permitted. This benefits both material usage and logistics and ultimately overall project costs.

It is to be noted that for a sealing mechanism within an end fitting of a traditional/ conventional structure such a differential pressure approach is not possible as the seal sits within a pipe annulus region. The external hydrostatic force is therefore not directly applied to a seal ring unless there has been a failure of an outer sheath. It will be appreciated that conventionally in such a situation any internal metallic layers would be subject to local corrosion with a corresponding reduction of the serviceable life of the product.

Certain embodiments of the present invention utilise a double seal arrangement whereby a first seal prevents pressure release from a bore of a pipe and a secondary seal allows reverse testing of the primary seal and/or allows a local hydrostatic pressure to be applied to a side of the primary seal without necessarily flooding an annulus region of the flexible pipe.

Certain embodiments of the present invention allow for nitrogen testing of a sealing mechanism at any time during manufacture or subsequent to a period of onshore storage. This negates the need for filling a pipe with water etc. to complete a full hydro test. Testing can also validate both internal pressure (of a primary seal) and external pressure (a secondary seal) integrity.

Certain embodiments of the present invention also provide the advantage that by allowing free flooding of a port during installation a primary seal will see a differential pressure only across the seal whilst a secondary seal will prevent annulus flooding by resisting the hydrostatic head.

Certain embodiments of the present invention provide for the automatic opening of a fluid communication passageway in an end fitting when a flexible pipe including the end fitting is submerged beyond a predetermined depth. The fact that a local hydrostatic pressure is always communicated to a desired location in use means that a differential pressure approach can be taken when the flexible pipe is designed and manufactured. Likewise an accumulated high pressure in a region of an end fitting can automatically be released as a flexible pipe including the end fitting are lifted towards a surface region subsequent to a period of use. This helps avoid harm to users.

Certain embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:.

Throughout this description, reference will be made to a flexible pipe. It will be understood that a flexible pipe is an assembly of a portion of pipe body and one or more end fittings in each of which a respective end of the pipe body is terminated. <FIG> illustrates how a portion of pipe body <NUM> (referred to as a segment) is formed from a combination of layered materials that form a pressure-containing conduit. Although a number of particular layers are illustrated in <FIG>, it is to be understood that the present invention is broadly applicable to coaxial pipe body structures including one or more layers manufactured from a variety of possible materials. For example, the pipe body may be formed from metallic layers, composite layers, or a combination of different materials. It is also to be further noted that the layer thicknesses are shown for illustrative purposes only.

As illustrated in <FIG>, the pipe body includes an optional innermost carcass layer <NUM>. The carcass provides an interlocked construction that can be used as the innermost layer to prevent, totally or partially, collapse of an internal pressure sheath <NUM> due to pipe decompression, external pressure, and/or tensile armour pressure and mechanical crushing loads. The carcass layer may be a metallic layer, formed from carbon steel or the like, for example. The carcass layer may also be formed from composite, polymer, or other material, or a combination of materials. It will be appreciated that certain embodiments of the present invention are applicable to 'smooth bore' operations (i.e. without a carcass) as well as such 'rough bore' applications (with a carcass).

The internal pressure sheath <NUM> acts as a fluid retaining layer and comprises a polymer layer that ensures internal fluid integrity. It is to be understood that this layer may itself comprise a number of sub-layers. It will be appreciated that when the optional carcass layer is utilised the internal pressure sheath may be referred to by those skilled in the art as a barrier layer. In operation without such a carcass the internal pressure sheath may be referred to as a liner.

The pressure armour layer <NUM> is a structural layer with elements having a lay angle close to <NUM>° that increases the resistance of the flexible pipe to internal and external pressure and mechanical crushing loads. The layer also structurally supports the internal pressure sheath, and is an interlocked construction of wires wound with a lay angle close to <NUM>°.

The flexible pipe body also includes an optional first tensile armour layer <NUM> and optional second tensile armour layer <NUM>. Each tensile armour layer is used to sustain tensile loads and internal pressure. The tensile armour layer may be formed from a plurality of metallic wires (to impart strength to the layer) that are located over an inner layer and are helically wound along the length of the pipe at a lay angle typically between about <NUM>° to <NUM>°. The tensile armour layers may be counter-wound in pairs. The tensile armour layers may be metallic layers, formed from carbon steel, for example. The tensile armour layers may also be formed from composite, polymer, or other material, or a combination of materials.

The flexible pipe body shown also includes optional layers <NUM> of tape which each help contain underlying layers and may act as a sacrificial wear layer to help prevent abrasion between adjacent layers.

The flexible pipe body also includes optional layers of insulation <NUM> and an outer sheath <NUM>, which comprises a polymer layer used to help protect the pipe against penetration of seawater and other external environments, corrosion, abrasion and mechanical damage.

Each flexible pipe thus comprises at least one segment of pipe body <NUM> together with an end fitting located at at least one end of the flexible pipe. An end fitting provides a mechanical device which forms the transition between the flexible pipe body and a connector. The different pipe layers as shown, for example, in <FIG>, are terminated in the end fitting in such a way as to transfer the load between the flexible pipe and the connector.

<FIG> illustrates a riser assembly <NUM> suitable for transporting production fluids such as oil and/or gas and/or water from a subsea location <NUM> to a floating facility <NUM>. For example, in <FIG> the subsea location <NUM> includes an end of a subsea flowline. The flexible flowline <NUM> comprises a flexible pipe, wholly or in part, resting on the sea floor <NUM> or buried below the sea floor and used in a static application. The floating facility may be provided by a platform and/or buoy or, as illustrated in <FIG>, a ship. The riser assembly <NUM> is provided as a flexible riser, that is to say a flexible pipe <NUM> connecting the ship to the sea floor installation. The flexible pipeline may be formed from a single segment or multiple segments of flexible pipe body with end fittings connected end-to-end.

It will be appreciated that there are different types of riser, as is well-known by those skilled in the art. Certain embodiments of the present invention may be used with any type of riser, such as a freely suspended riser (free, catenary riser), a riser restrained to some extent (buoys, chains) or totally restrained riser. Certain other embodiments of the present invention can be used as flowlines or jumpers or the like and also with hybrid pipe structures including sections of flexible pipe and rigid pipe.

<FIG> illustrates how an end <NUM> of a segment of flexible pipe body <NUM> is terminated in an end fitting <NUM>. As illustrated in <FIG> the end fitting <NUM> includes an end fitting jacket <NUM> which is securable to an end fitting body <NUM>. The end fitting body <NUM> is a unitary piece which has a first end region that defines an open mouth in which the end <NUM> of the flexible pipe body is received. As illustrated in <FIG> an inner surface <NUM> of the end fitting body <NUM> has a stepped cross section which generally widens towards a pipe facing end <NUM> of the end fitting body <NUM>. The inner surface faces layers of the flexible pipe body when the pipe body is terminated in the end fitting. An outer surface of the end fitting body <NUM> extends from the pipe facing and open mouthed end <NUM> of the end fitting body to a flange <NUM> which extends radially outwardly from a central region of the end fitting body <NUM>. The flange part <NUM> of the end fitting body is secured to an end of the jacket <NUM> by conventional techniques (such as bolts or threaded connections or the like). When so secured a space <NUM> is provided between the jacket and the end fitting body <NUM> in which armour wires <NUM> of the flexible pipe body can be terminated. Aptly the space <NUM> is filled with an epoxy during a manufacturing step during which flexible pipe body is terminated in the end fitting <NUM>. As illustrated in <FIG> an external port <NUM> is provided on an outwardly facing surface <NUM> of the end fitting body. The outwardly facing surface is a part of the end fitting that experiences local hydrostatic pressure in use. Other such surfaces are the outer cylindrical surface and end fitting connector (not shown) at the remaining end region of the end fitting body. A test pressure may optionally be applied locally at the external port prior to use of the pipe. A through bore <NUM> extends through the flange part <NUM> of the end fitting body to a tube connector <NUM> which connects a further end of the bore <NUM> that is spaced apart from the port <NUM> to a pressure resistant tube <NUM>. The pressure resistant tube <NUM> helps provide a passageway that is collapse and burst resistant at high pressures. That is to say when fluid at high pressure is in the tube <NUM> the walls of the tube do not collapse or burst. Likewise the bores in the end fitting body do not collapse or burst. Aptly the tube is a stainless steel tube. Aptly the tube is manufactured using corrosion resistant material. Aptly the bores in the end fitting body are lined or clad with a corrosion resistant material. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more.

A further end <NUM> of the tube is connected to a further tube connector <NUM> which connects the tube to an end of another bore <NUM> through the end fitting body. This bore <NUM> extends radially outwardly from the inner surface of the end fitting body <NUM> to an outer surface of the end fitting body that faces the inside of the jacket.

A remaining end of the bore <NUM> through the end fitting body <NUM> near the open mouthed end <NUM> defines an inner port <NUM>. This inner port <NUM> is located at a position between a primary seal ring <NUM> and secondary seal ring <NUM> which seal against a fluid retaining layer of the flexible pipe body.

During a termination process in which an end of a segment of flexible pipe body is terminated in the end fitting <NUM> a carcass latch ring <NUM> and inner sleeve <NUM> are located with respect to a carcass <NUM>, sacrificial layer <NUM> and a barrier layer <NUM>. The seal rings <NUM>, <NUM> thus bear on a radially outer surface of the barrier layer <NUM>. During the termination process the primary seal <NUM> is energised against the outer surface of the barrier layer <NUM> by securing an inner collar member <NUM> against the end <NUM> of the end fitting body <NUM>. An "O" ring <NUM> helps create a seal at an interface between the inner collar member <NUM> and the end fitting body <NUM>. Subsequently the secondary seal ring <NUM> is energised by securing a pressure armour collar <NUM> to the inner collar member <NUM> which action urges a pressure armour termination ring <NUM> and corresponding spacer ring <NUM> against an abutment end of the secondary seal ring <NUM>. This process urges the secondary seal ring <NUM> against the outer surface of the barrier layer <NUM>.

The first (or primary) sealing ring <NUM> and second (that is to say secondary) sealing ring <NUM> have a similar inner diameter and radius but, as illustrated in <FIG> may not be identical. Rather an abutment end of one may be larger and have a different shape to the other. Each has a block like abutment end from which a sealing lip extends. The lip is tapered. Aptly the lip is wedge like. Aptly the lip has a serrated inner surface. The inner port <NUM> can be used as a test port or as a hydrostatic pressure communicating port. That is to say if a test pressure is applied locally at the external port <NUM> or if a hydrostatic pressure is applied locally at the external port <NUM> then this pressure is communicated inside the end fitting via the fluid communication passageway. This passageway is provided by the bore <NUM> in the flange <NUM> and the connecting tube <NUM> and the bore <NUM> in the open mouthed end of the end fitting body. Thus a corresponding test pressure or hydrostatic pressure is experienced at the internal port <NUM> on the inner surface of the end fitting body. When a test pressure is applied locally at the external port <NUM> the applied pressure is used to verify that the primary and secondary seals have been correctly energised during manufacturing. This can be achieved by applying a test pressure and then monitoring any degradation in the applied pressure for a predetermined period of time. Such degradation in pressure indicates one or more leak paths which permit pressure in the fluid communication passageway to escape. This helps test seal integrity of the seals that are created. During an in service lifetime of the flexible pipe body and end fitting the local hydrostatic pressure is continually applied at the external port <NUM>. In the circumstances where the flexible pipe is put into service in deep or ultra deep water environments the local pressure at the external port <NUM> can be in the range of about around <NUM> to <NUM> kPa (<NUM> to <NUM> psi) or more. This pressure is constantly applied via the fluid communication passageway to the internal port <NUM> between the sealing rings. As a result the primary sealing ring <NUM> experiences a reduced pressure difference across it. That is to say one side of the primary sealing ring <NUM> experiences a bore pressure whilst a remaining side of the primary sealing ring <NUM> experiences the local hydrostatic pressure. By way of example, where a bore pressure is <NUM> kPa (<NUM>,<NUM> psi) and a local hydrostatic pressure is <NUM> kPa (<NUM> psi) the primary seal sees only a difference of <NUM> kPa (<NUM>,<NUM> psi). This is in contrast to a primary seal ring in a conventional situation where local hydrostatic pressure is not communicated to one side of the seal ring which thus experiences a greater <NUM> kPa (<NUM>,<NUM> psi) difference.

The duel sealing ring technique allows a high test pressure or hydrostatic pressure to be communicated to one side of a primary seal ring without that pressure being communicated to a pipe annulus.

<FIG> illustrates an alternative arrangement whereby hydrostatic pressure is communicated to a position behind and between a double seal provided by a single double facing sealing ring <NUM>. Such a ring is formed as an integral piece with two opposed lips <NUM> extending from a central body region <NUM>. The sealing ring <NUM> has a generally open V-shape which is energised from both sides to create a double seal. Optionally one or more small holes <NUM> are formed at an apex region of the sealing ring <NUM> to allow hydrostatic pressure to be communicated from the bore <NUM> past the seal to the void space created between the two sealing areas and the underlying barrier layer <NUM>.

<FIG> illustrates how an end <NUM> of a segment of flexible pipe body is terminated in an alternative end fitting <NUM>. The end fitting <NUM> includes an end fitting jacket <NUM> (not shown) which is securable to an end fitting body <NUM>. The end fitting body <NUM> defines an open mouth in which the end <NUM> of the flexible pipe body is received. As illustrated in <FIG> an inner surface <NUM> of the end fitting body <NUM> has a stepped cross section which generally widens towards a pipe facing end <NUM> of the end fitting body <NUM>. The inner surface faces layers of the flexible pipe body when the body is terminated in the end fitting. An outer surface of the end fitting body <NUM> extends from the pipe facing an open mouthed end <NUM> of the end fitting body to a flange <NUM> (not shown) which extends radially outwardly from a central region of the end fitting body <NUM>. The flange part <NUM> of the end fitting body is secured to an end of the jacket <NUM> by conventional techniques such as via bolts, threaded connections or the like. When so secured a space <NUM> is provided between the jacket and the end fitting body <NUM> in which armour wires <NUM> of the flexible pipe body can be terminated. Aptly the space <NUM> is filled with an epoxy during a manufacturing step during which flexible pipe body is terminated in the end fitting <NUM>. An external port <NUM> (not shown) is provided on an outwardly facing surface <NUM> of the end fitting body. The outwardly facing surface is a part of the end fitting that experiences local hydrostatic pressure in use. Other such surfaces are the outer cylindrical surface and end fitting connector at the remaining end region of the end fitting body. As per the end fitting illustrated in <FIG> a through bore <NUM> extends through the flange part <NUM> of the end fitting body to a tube connector <NUM> which connects a further end of the bore <NUM> that is spaced apart from the port <NUM> to a pressure resistant tube <NUM>. The pressure resistant tube <NUM> helps provide a passageway that is collapse resistant at high pressures. That is to say when fluid at high pressure is in the tube <NUM> the walls of the tube do not collapse or burst. Likewise bores in the end fitting body do not collapse or burst.

A further end <NUM> of the tube is connected to a further tube connector <NUM> which connects the tube to an end of another bore <NUM> which extends through the end fitting body. This bore <NUM> extends radially outwardly from the inner surface of the end fitting body <NUM> to an outer surface of the end fitting body that faces the inside of the jacket. A remaining end of the bore <NUM> through the end fitting body <NUM> near the open mouthed end <NUM> defines an inner port <NUM>. This inner port <NUM> is located at a position between a primary seal ring <NUM> and a secondary seal ring <NUM> which each seal against a respective but different fluid retaining layer of the flexible pipe body. By contrast to the end fitting illustrated in <FIG> the seal rings of the end fitting illustrated in <FIG> do not seal against a common layer. Rather one sealing ring seals against an outer surface of one layer and a further seal ring seals against an outer surface of another layer. For example as illustrated in <FIG> the primary seal ring <NUM> may seal against an outer surface of a barrier layer whilst a secondary seal ring <NUM> seals against an outer surface of an overlying sacrificial layer <NUM>.

During a termination process in which an end of a segment of flexible pipe body is terminated in the end fitting <NUM> a carcass latch ring <NUM> and inner sleeve <NUM> are located with respect to a carcass <NUM>, sacrificial layer <NUM> and barrier layer <NUM>. During the termination process the primary seal ring <NUM> is energised against the outer surface of the barrier layer <NUM> by securing an inner collar <NUM> against the end <NUM> of the end fitting body <NUM>. An "O" ring <NUM> helps create a seal at an interface between the inner collar member <NUM> and the end fitting body <NUM>. Subsequently the secondary seal ring <NUM> is energised by securing a pressure armour collar <NUM> to the inner collar member <NUM> which action urges a pressure armour termination ring <NUM> and corresponding spacer ring <NUM> against an abutment end of the secondary seal ring <NUM>. This process urges the secondary seal ring <NUM> against the outer surface of the sacrificial layer <NUM>.

As with the end fitting shown in <FIG>, the end fitting illustrated in <FIG> allows a locally applied test pressure or local hydrostatic pressure to be communicated as desired to a location between seal rings. Applying a test pressure enables sealing elements to be tested during a termination process in which an end of flexible pipe body is terminated in an end fitting. Alternatively a test pressure can be applied at any stage subsequent to manufacture. For example subsequent to the elapse of a period of time in which manufactured flexible pipe is stored. Alternatively in use, after installation at a subsea location, a fluid communication passageway provided by an external port, bore, tube, bore and port can be used to constantly communicate a local pressure to the location between the seal rings. This pressure can be a pressure generated by a head of water at a depth where the flexible pipe and end fitting is submerged. Aptly in service the pressure generated by the head of water is transmitted through the communication pathway without valves or other impedance. In this way not only does the seawater communicate in to the inner port <NUM> between the primary seal <NUM> and the secondary seal <NUM> but also gas which has permeated through the barrier layer <NUM> into the void space between the barrier layer <NUM> and the overlying seal layer <NUM> may escape out from the end fitting through the same high pressure communication pathway (overcoming the local hydrostatic pressure).

<FIG> illustrates how an end <NUM> of a segment of flexible pipe body <NUM> is terminated in an end fitting <NUM>. As illustrated in <FIG> the end fitting <NUM> includes an end fitting jacket <NUM> which is securable to an end fitting body <NUM>. The end fitting body <NUM> is a unitary piece which has a first end region that defines an open mouth in which the end <NUM> of the flexible pipe body is received. As illustrated in <FIG> an inner surface <NUM> of the end fitting body <NUM> has a stepped cross section which generally widens towards a pipe facing end <NUM> of the end fitting body <NUM>. The inner surface faces layers of the flexible pipe body when the pipe body is terminated in the end fitting. An outer surface of the end fitting body <NUM> extends from the pipe facing and open mouthed end <NUM> of the end fitting body to a flange <NUM> which extends radially outwardly from a central region of the end fitting body <NUM>. The flange part <NUM> of the end fitting body is secured to an end of the jacket <NUM> by conventional techniques (such as bolts or threaded connections or the like). When so secured a space <NUM> is provided between the jacket and the end fitting body <NUM> in which armour wires <NUM> of the flexible pipe body can be terminated. Aptly the space <NUM> is filled with an epoxy during a manufacturing step during which the flexible pipe body is terminated in the end fitting <NUM>. As illustrated in <FIG> an external port <NUM> is provided on an outwardly facing surface <NUM> of a valve. A through bore <NUM> extends away from the external port <NUM> through the flange part <NUM> of the end fitting body to a tube connector <NUM> which connects a further end of the bore <NUM> that is spaced apart from the external port <NUM> in the valve to a pressure resistant tube <NUM>. The pressure resistant tube <NUM> helps provide a passageway that is collapse and burst resistant at high pressures. That is to say when fluid at high pressure is in the tube <NUM> the walls of the tube do not collapse or burst. Likewise the bores in the end fitting body do not collapse or burst. Aptly the tube is a stainless steel tube. Aptly the tube is manufactured using corrosion resistant material. Aptly the bores in the end fitting body are lined or clad with a corrosion resistant material. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more.

A further end <NUM> of the tube is connected to a further tube connector <NUM> which connects the tube to an end of another bore <NUM> that extends through the end fitting body. This bore <NUM> extends radially outwardly from the inner surface of the end fitting body <NUM> to an outer surface of the end fitting body that faces the inside of the jacket.

A remaining end of the bore <NUM> that passes through the end fitting body <NUM> near the open mouthed end <NUM> defines an inner port <NUM>. This inner port <NUM> is located at a position between a primary seal ring <NUM> and a secondary seal ring <NUM> which, in the example shown, seal against a common fluid retaining layer of the flexible pipe body.

The inlet valve <NUM> is a one way valve that has a closed state and an open state. In the closed state the valve blocks any fluid flow through the bore <NUM> in the end fitting body <NUM> and the external port <NUM>. In an open state local external pressure P<NUM>, which may be a hydrostatic pressure is fluidically communicated via the external port <NUM> along the fluid communication passageway to the internal port <NUM>. Aptly the valve <NUM> is a high pressure ball valve. The valve is designed and manufactured to open at a respective predetermined pressure. Aptly the predetermined opening pressure of the valve is a pressure associated with a particular depth of water in which the end fitting and flexible pipe is submerged. Aptly the open pressure threshold is <NUM> kPa (<NUM> psi) or more. Aptly the open pressure is <NUM> psi or more. Aptly the open pressure is <NUM> (<NUM> psi) or more. In this way when the flexible pipe is installed at a desired subsea location, fluid pressure is not communicated to the internal port <NUM> until the flexible pipe is submerged at a predetermined water depth. At that predetermined point in time corresponding to the end fitting, carrying the valve <NUM>, being at a predetermined water depth, the valve <NUM> opens and the local hydrostatic pressure is communicated to the internal port <NUM>. It will be appreciated that one or more externally located inlet ports <NUM> of respective inlet valves and corresponding fluid communication passageways may be provided in each end fitting. Aptly multiple external inlet ports and corresponding fluid communication passageways are included in the end fitting with a corresponding number of internal ports <NUM>. Aptly the inlet ports, valves, fluid communication passageways and internal ports are arranged circumferentially around the end fitting.

<FIG> illustrates a cross section through a part of the end fitting shown in <FIG> and illustrates how in addition to inlet valves and inlet passageways an end fitting <NUM> can include one or more external exit ports <NUM> (one shown in <FIG>). The exit port is formed in an outer surface <NUM> of an exit valve. A corresponding through bore <NUM> extends through the flange part <NUM> of the end fitting body to a tube connector <NUM> which connects a further end of the bore <NUM> that is spaced apart from the exit port <NUM> to a pressure resistant tube <NUM>. The pressure resistant tube <NUM> helps provide a passageway that is collapse and burst resistant at high pressures. That is to say when fluid at a high pressure is in the tube <NUM> the walls of the tube do not collapse or burst. Likewise the bores in the end fitting body do not collapse or burst. Aptly the tube is a stainless steel tube. Aptly the tube is manufactured using corrosion resistant material. Aptly the bores in the end fitting body are lined or clad with a corrosion resistant material. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more. Aptly the walls of the tube <NUM> are pressure resistant to a pressure of <NUM> kPa (<NUM> psi) or more.

A remaining end of the bore <NUM> through the end fitting body <NUM> near the open mouthed end <NUM> defines an inner port <NUM>. This inner port <NUM> is located at a position between a primary seal ring <NUM> and a secondary seal ring <NUM> which seal against a fluid retaining layer of the flexible pipe body.

The valve <NUM> associated with the exit port <NUM> and the exit passageway provided by the through bore <NUM> in the flange of the end fitting body <NUM> is a one way valve. The exit valve <NUM> has an open state and a closed state. In the closed state fluid, and thus pressure, communication does not occur between the exit port <NUM> on the outer surface <NUM> of the exit valve <NUM> and the inner port <NUM>. In the open state a build-up of internal pressure P<NUM> at the region around the inner port <NUM> is released outwardly via the exit port <NUM> into a surrounding region. Aptly the exit valve <NUM> is a high pressure ball valve. The exit valve <NUM> opens when a local pressure P<NUM> external to the end fitting is no longer high enough to force the valve into a closed state. This results in the valve being open until it is submerged at a predetermined depth of seawater. At the predetermined depth a pressure exerted by the local hydrostatic pressure P<NUM> reaches the predetermined threshold pressure for the valve which thus closes. The depth at which the valve changes state from open to closed and from closed to open may optionally be the same as when the inlet valve <NUM> discussed with respect to <FIG> changes state. Aptly the inlet valves open at a lower hydrostatic pressure than the exit valves open.

By way of example the pressure control valve <NUM> may be set, for example, to open when the external pressure P<NUM>, or a test pressure P<NUM> applied to the external side of the pressure control valves, is greater than or equal to <NUM> kPa (<NUM> bar/<NUM> psi). The pressure control exit valve <NUM> is a one-way valve which opens where P<NUM> is greater than P<NUM> (or is greater than an applied test pressure P<NUM> on the external side of the pressure control exit valve <NUM>). That is to say when a pressure P<NUM> in an annulus region between the opposed seal rings <NUM>, <NUM> (and which is communicated via the internal fluid communication pathway), is greater than the external pressure P<NUM> the pressure control exit valve opens. During end fitting and prior to installation the external pressure P<NUM> is <NUM> kPa (<NUM> atm/<NUM> bara). Thus P<NUM> is equal to P<NUM> and the inlet valve <NUM> is closed and the exit valve <NUM> is closed. When a test pressure P<NUM> is applied to the inlet valve <NUM> to test the seals (and for the purpose of the test the same test pressure is applied to the exit valve <NUM>) the inlet valve opens and P<NUM> is equal to P<NUM>. With the annulus region between the opposed seal rings <NUM>, <NUM> pressurised the normal pipe FAT test pressure cycle can be performed in the bore of the pipe, providing confirmation of the differential pressure containment across the inner seal ring required by the pipe in service. When the test pressure P<NUM> is removed at the external valves the inner annulus pressure P<NUM> is greater than the external pressure P<NUM> and therefore the valve <NUM> opens to release the pressure P<NUM> in the annular region until P<NUM> = P<NUM> again at which point the valve <NUM> closes again. By contrast, when the pipe is installed P<NUM> increases with water depth and the external pressure P<NUM> is greater than the pressure in P<NUM> in the annular region until the set differential pressure is reached (e.g. <NUM> kPa/<NUM> bara/<NUM> psi) at which point in time the inlet valve <NUM> opens (the valve <NUM> remains closed). The external pressure P<NUM> and the pressure P<NUM> in the annular region are equalised as a result of the opening of the valve <NUM>. If the pipe is recovered the valve <NUM> closes and so P<NUM> becomes greater than the external pressure P<NUM> as the end fitting rises through the water column. Because the internal pressure P<NUM> is now greater than the external pressure P<NUM> the valve <NUM> opens and the pressure at the openings <NUM>, <NUM> in the annular region is released again until the internal pressure P<NUM> is equal to the external pressure P<NUM>.

<FIG> helps illustrate how inlet and outlet valves <NUM>, <NUM> can be arranged circumferentially around an external back surface <NUM> of the flange part of the end fitting <NUM> in more detail. As illustrated in <FIG> two inlet valves <NUM> and two exit valves <NUM> may be arranged substantially opposite each other. It will be appreciated that other numbers of inlet and outlet valves and corresponding passageways and ports can be utilised according to certain embodiments of the present invention. The number of inlet valves/ports does not have to equal the number of exit valves/ports.

Aptly, according to certain embodiments of the present invention the pressure at the external port may be communicated directly or indirectly. That is to say fluid may be allowed to flow throughout the passageway or alternatively part or parts of the passageway may be filled with a pressure communicating fluid such as a grease or hydraulic oil or the like. Aptly different regions of the fluid communication passageway contain different fluid communicating fluids which are separated as required by one or more filters able to communicate pressure but which constrain flow of different fluids across an interface region.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to" and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of the features and/or steps are mutually exclusive. The invention is not restricted to any details of any foregoing embodiments. The invention extends to any novel one, or novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claim 1:
An end fitting (<NUM>, <NUM>, <NUM>) for a flexible pipe for transporting production fluids, comprising:
an end fitting body (<NUM>) comprising a first end region that provides an end fitting connector and a further end region (<NUM>, <NUM>, <NUM>) that provides an open mouth for receiving a flexible pipe body end (<NUM>); and
an end fitting jacket (<NUM>, <NUM>, <NUM>) secured to the end fitting body; wherein
the end fitting body (<NUM>) further comprises at least one external port (<NUM>, <NUM>, <NUM>, <NUM>) of the end fitting located on an outwardly facing surface (<NUM>, <NUM>, <NUM>, <NUM>) of the end fitting body (<NUM>) for receiving a local hydrostatic pressure exerted by a surrounding body of seawater in use, at least one corresponding inner port (<NUM>, <NUM>, <NUM>, <NUM>) located on an inwardly facing surface of the end fitting body (<NUM>) and a corresponding fluid communication passageway (<NUM>, <NUM>, <NUM>, <NUM>), pressure resistant to at least about around <NUM> kPa (<NUM> psi), extending between the external port (<NUM>, <NUM>, <NUM>, <NUM>) and the inner port (<NUM>, <NUM>, <NUM>, <NUM>) for communicating pressure between said external port (<NUM>, <NUM>, <NUM>, <NUM>) and said inner port (<NUM>, <NUM>, <NUM>, <NUM>), wherein said fluid communication passageway comprises at least one lumen (<NUM>, <NUM>, <NUM>, <NUM>) connected between a first bore (<NUM>, <NUM>, <NUM>, <NUM>) in the end fitting body extending between a first lumen end and the inner port, and a further bore (<NUM>, <NUM>, <NUM>, <NUM>) in the end fitting body extending between a further lumen end and the external port, wherein the first bore extends radially outwardly from an inner surface of the end fitting body to an outer surface of the end fitting body that faces an inside of the jacket, said inner port (<NUM>, <NUM>, <NUM>, <NUM>) being located at a location between a pair of spaced apart seal elements (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) sealed against at least one internal fluid retaining layer of a flexible pipe body.