OA19104A - Crush propagation limitation flange connection piece comprising a differential pressure valve for underwater fluid transport pipe. - Google Patents

Abstract

The invention relates to a differential pressure valve connection piece (100) for an underwater fluid transport pipe, comprising a valve body (102) inside which an internal chamber (106) opening. on one side towards the pipe and opening on the other side towards the outside, a piston (110) arranged so as to separate the internal chamber into an inlet chamber (106a) and a discharge chamber (106b), the piston being movable between an open position in which the intake and discharge chambers communicate with each other and a closed position in which the intake and discharge chambers are sealed relative to one another, a calibration screw (112) screwed into the valve body and comprising a bore (114) inside which slides a rod (116) of the piston (110) and at least one bore (118) opening into the delivery chamber and opening towards the outside, and a spring (120) calibrated so rte to maintain the piston in the closed position below a predetermined threshold pressure inside the intake chamber.

Description

Title of invention

Differential pressure valve for an underwater fluid transport pipe and flange-limiting connection piece for crushing propagation, comprising such a valve

Invention background

--------- The present invention relates to the general field of manna pipes lying at the bottom of the sea or ensuring the bottom-surface connection for the transport of hydrocarbons, for example oil and gas, ioouo do well oouo-marino production.

More specifically, it relates to a differential pressure valve fitted to the underwater pipes (single or double jacket) which are provided with an internal plastic lining for transporting hydrocarbons.

The submarine hydrocarbon transport pipes, with single or double casing, can be covered on their internal surface by an annular jacket enclosing the hydrocarbon fluids under pressure to be transported. Generally, this jacket is made of plastic, for example made from polyethylene, nylon and fluorinated polymers.

The life of such a liner depends in particular on the speed at which the plastic which constitutes it degrades by chemical reaction on contact with the compounds of the flow of hydrocarbons transported. For fluids at low temperatures or containing few molecules of water, a plastic based on high density polyethylene (PE-HD) and nylon can be used. For fluids at higher temperatures or containing more water, a more thermally stable plastic is required.

----------------------- Dang fp raq nn could rpcnurir at pnlymèrpq flnnt-pg, tp | q gnp rin ---------- -------------------- polyvinylidene fluoride (English acronym: PVDF for "PolyVinyliDene

Fluoride ”).

In addition, the internal linings fitted to the submarine conduits are permeable to low molecular weight hydrocarbons. Also, in production, a continuous flow of gas (called permeation gas) diffuses through the liner and fills the annular space formed between the liner and the internal surface of the pipe. The flow rate of the permeation gas diffusing in this way through the jacket depends on many factors, and in particular on the coefficient of permeability of the plastic constituting the jacket, this coefficient of permeability resulting directly from the composition of the plastic used.

Permeation gases can accumulate in the annular space between the liner and the inner wall of the pipe. However, in this situation, following a rapid depressurization of the pipe, the ------ risk is important that the jacket does not collapse on itself. It is therefore necessary to evacuate these gases out of the annular space in which they diffuse. For this purpose, it is known to install at the ends of the pipe 10 differential valves; ceo goupopoo o'entrent on one side in the annular space formed between the liner and the pipe and opening on an opposite side towards the ambient environment, namely sea water. When the pressure inside the the annular space formed between the liner and the pipe exceeds a predetermined threshold, typically of the order of 1 to 5 bars above the local hydrostatic pressure, the valves open and allow the permeation gases to be evacuated outside the pipe, in the sea.

Reference may be made to document WO 99/56045, which describes an exemplary architecture of a differential pressure valve used to evacuate permeation gases from a flexible submarine pipe.

This valve includes in particular a double valve, which makes it quite complex to produce. Furthermore, in this document, simple gas bubbles constitute the only barrier to the penetration of water and solid particles into the chamber of the valve. However, such a barrier is relatively unsealed.

Subject and summary of the invention ____________________________________________________

--------------------- The present-invention-therefore-has-for-main-purpose-to-propose a ---------- ------------- differential pressure valve which does not have such disadvantages.

According to the invention, this object is achieved by means of a differential pressure valve for an underwater fluid transport pipe, the valve comprising:

a valve body inside which an internal chamber is formed opening on one side towards the pipe inside which ^ there is an internal pressure Pi and opening on the other side towards the outside where there is a external pressure Pe;

a piston arranged in the internal chamber so as to separate the internal chamber into an inlet chamber 5 communicating with the interior of the pipe and a delivery chamber communicating with the exterior, the piston being movable between ---- a open position in which the intake chambers and in which the intake and discharge chambers are sealed

10 ............. in relation to the self ';

a calibration screw screwed into the valve body and comprising a bore inside which slides a piston rod and at least one bore opening into the delivery chamber and opening towards the outside; and a spring positioned between the piston and the calibration screw, said spring being calibrated so as to keep the piston in the closed position below a predetermined threshold pressure inside the intake chamber.

The permeation gases present inside the annular space between the lining and the internal wall of the pipe diffuse through the lining of the pipe and penetrate into the inlet chamber of the valve. When the pressure inside the intake chamber exceeds the predetermined threshold pressure (typically corresponding to a pressure difference with the external pressure

Pe of the order of 1 to 5 bars), the valve piston opens allowing ________________ permeation gases to enter the discharge chamber to be evacuated to the outside of the pipe. In addition, the calibration screw which ----------- is-screwed-in-the-valve-body-permeLde-adjust-the-calibration-clLiressort and thus to modify the pressure threshold from which the piston opens to evacuate permeation gases. The valve according to the invention thus has an extremely simple design, which makes it reliable and easy to manufacture.

Preferably, the holes in the calibration screw open outwards through a filter intended to retain impurities coming from the outside. The presence of such a filter makes it possible to avoid the passage of impurities from the outside, in particular sand when the pipe rests at the bottom of the sea, towards the inside of the valve.

In this case, the filter advantageously opens outwards through a membrane held in position by means of a spring 5 working in compression. Such a membrane allows the sea water contained in the filter to pass through while retaining the salts of the sea water and other dusts in order to prevent them from penetrating into

..... i engineer in the valve chamber. .................................................

The admission chamber can communicate with the interior of the 10 ...... porllntcrmcdioire conduct of a ^ Qnoliootion ^ DonO'-o-caBHD'Onaliontion 'preferably opens at one end into the admission chamber and opens at an opposite end inside the pipe via a strainer. The presence of such a strainer makes it possible to retain the dust and the steel particles present in the annular space which could be entrained by the permeation gases during their evacuation through the valve.

The invention also relates to a junction piece for an underwater pipe for transporting fluids, comprising a ring intended to be connected to the ends of two unitary pipe elements, a flange for limiting the propagation of crushing projecting radially outward from the ring, and at least three differential pressure valves as defined above, the valves being positioned radially within the flange.

The internal chamber of each valve can open on one side inside the ring and opens on the other side towards the outside of the __________________ flange. More specifically, the internal chamber of each valve can open on one side inside the ring through a liner made of --------- plastic-material .---- - --------- ----------- Preferably, the valves are regularly spaced from each other around an axis of revolution of the flange. Such an arrangement ensures that at least one valve does not open onto the seabed on which the flange rests in operation.

In the case of a junction piece for underwater pipe with a double jacket, the ring is an internal ring intended to be connected to the ends of two unit elements of an internal pipe jacket, the junction piece comprising in addition to an outer ring disposed around the inner ring while being coaxial with it and intended to be connected to the ends of two unitary elements of an outer pipe casing, the flange projecting radially outward from the outer ring.

BRIEF DESCRIPTION OF DRAWINGS _{OF another.5 character} j e _{r S e} t tiqLi _are: advantages of the present invention will become apparent ..................... ..... of the description given below, with reference to the accompanying drawings which illustrate an exemplary embodiment devoid of all the 0'-CB'iÎret! èi ^, c ^, liiTritatifrSiai ^M le ⁱ s ^, figui ^, e3! .----

- Figure 1 is a perspective view of a junction piece for underwater pipe with double jacket provided with differential pressure valves according to the invention;

- Figure 2 is a longitudinal sectional view of the connecting piece of Figure 1;

- Figure 3 is a cross-sectional view and in situation of the connecting piece of Figure 1;

- Figure 4 is a longitudinal sectional view of one of the valves of Figures 1 to 3; and

- Figure 5 is a perspective view of a junction piece for a single-walled submarine pipe fitted with differential pressure valves according to the invention.

Detailed description of the invention

The invention applies to all underwater pipes ___________________ laying at the bottom of the sea or ensuring the bottom-surface connection for the ______________ transport of hydrocarbons, these pipes being able to be with single casing ---------- ---- or double-wrapped .— -

The invention applies more particularly to submarine pipes for which the pressurized hydrocarbon fluids to be transported are confined in a plastic jacket, this jacket being permeable to low molecular weight hydrocarbons which form a flow of permeation gas. to be evacuated outside the pipe (typically these permeation gases include H2S, CO2, CH ₄ , and are mixed with water). _

To evacuate these permeation gases, the invention proposes a differential pressure valve which is fitted to such underwater pipes.

According to an advantageous arrangement of the invention, such differential pressure valves are positioned at the level of the junction pieces which are typically intended to ensure a junction between ------------------ - two unitary driving elements. Such connecting pieces are ---------..... generally forged steel connecting pieces. An exemplary embodiment of these connecting pieces is described in particular in the

Figures 1 and 2 illustrate, in perspective and in longitudinal section, an embodiment of a junction piece 2 for connecting between two sections of a double-walled pipe.

In this nonlimiting exemplary embodiment, the submarine pipe is a double-walled pipe which is formed by assembling a plurality of pipe sections together, each pipe section comprising a unitary inner jacket element and a unitary element of external envelope coaxial with the preceding one.

In known manner, the junction piece 2 is a piece of revolution centered on an axis of revolution X-X. It notably comprises an internal ring 4 which is intended to be connected to the ends of two unitary elements of an internal envelope of the double-envelope pipe, and an external ring 6 which is arranged around the internal ring 4 while being coaxial and which is intended to be connected to the ends of two unit elements of an ___ outer casing of said pipe. The annular space 8 delimited between the inner and outer rings can contain an insulation material (no ------ ---------- rpprpçpntp ςι ir | ρς figi irpç) ---- - --------- --------- The inner and outer rings have diameters corresponding substantially to the respective diameters of the unitary inner and outer shell elements on which they are assembled by welding. In addition, these rings are connected to each other at an annular central part 10.

The junction piece 2 also comprises an annular lining 12 made of plastic material which covers the internal surface of the internal ring 4, this lining receiving the hydrocarbon fluids under pressure to be transported. In known manner, the jacket is made of a plastic material which may contain polyethylene, nylon and fluorinated polymers.

At the central part 10, the junction piece 25 further comprises a flange limiting the spread of crushing 14 which projects radially outward from the outer ring 6. At the level of the pipe as a whole , the different flanges 14 ...... form local excess thicknesses at regular intervals along the pipe which serve to limit the risk of a spreading of a crushing 10 do lo.-GORdbiit (a-'6GHjrr ».l 'effg> t — dQÎij-i ^ stabilitàs — elCÎ — fermia — dos — co <ï! tiorî! Î3 — d <a · conduct driven by the external hydrostatic pressure of sea water.

The flange 14 thus constitutes a device for limiting the propagation of crushing (called "buckle arrestor" in English). In known manner, thanks to these devices, in the event of initiation and propagation of crushing of the pipe, the latter remains limited to the interval between the two flanges which surround the initiation of crushing.

The crushing propagation limitation flange 14 of the junction piece is provided with differential pressure valves 100 20 according to the invention which are each intended to ensure an evacuation towards the outside of the permeation gases diffusing through the lining 12.

More specifically, the differential pressure valves 100 each extend in the direction of their length in a radial direction D relative to the junction piece and open inside the internal ring 4 of the junction piece. in the same transverse plane to _______________________ this junction piece ._____________________________________ ________________________________________________________________

In addition, as shown in Figure 3, the differential pressure valves are ^ at least three - and ^ sonL-.de.-.- preferably. regularly distributed around the axis of revolution X-X of the junction piece. Such a 120 ° spacing between the valves makes it possible to always have at least one valve which opens into the ambient environment, namely seawater, even if the other two valves are silted up in the seabed 16 as shown in figure 3.

In connection with FIG. 4, the architecture of the differential pressure valve 100 according to the invention will now be described.

This valve notably comprises a valve body 102 which is formed by the flange 14 of the junction piece and inside which an internal chamber 106 is formed. This internal chamber opens on one side into the annular space 108 formed between the inner surface 5 of the inner ring 4 and the liner 12 and inside which prevails an internal pressure Pi. on the opposite side, the internal chamber opens towards the _former ty _r ie _Ur, that is, say in the ambient environment (ie the sea) where there is an external pressure Pe ·

A piston 110 is disposed in the internal chamber 106 so

110 o dâportogor-oollo-oi-on-idno-chQffîbro-d ^ dmisoion — lO (? OCommuniquanÎ with the annular gap 108 and a delivery chamber 106b communicating with the outside.

The piston 110 is between two extreme positions, namely an open position in which the inlet chambers 106a and discharge 106b communicate with each other, and a closed position shown in FIG. 4 and in which the chambers inlet and outlet are sealed from each other.

In its closed position, the piston 110, the rounded end of which rests on a frustoconical seat so as to ensure a perfect seal between the inlet and outlet chambers while avoiding any risk of blockage of the piston.

The valve also includes a set screw 112 which is screwed into the valve body. This calibration screw comprises a bore 114 inside which the rod 116 of the piston 110 slides, as well as one or more bores 118 opening into the discharge chamber 106b _______________________ and opening towards the outside ._____________________________________________________________________________

The valve also includes a spring 120 which is positioned --------- between the piston 440-and-the-v.is-d & jarag & -112 _T -c & jesscct-étaflt4aré so as to— keep the piston in the closed position below a pressure of a predetermined threshold Ps within the inlet chamber 106a. The adjustment of this threshold pressure is carried out by screwing or unscrewing more or less the setting screw 112.

Preferably, the holes 118 of the calibration screw 112 open outwards through a filter 122 which makes it possible to retain impurities coming from the outside. Thus, the filter 122 prevents the passage of impurities from the outside, in particular sand when the pipe., ^ I

rests at the bottom of the sea, towards the inside of the valve. On the other hand, the filter is permeable to permeation gases (including H ₂ S, C0 ₂ , CH ₄ ) and to water.

Preferably also, the filter 122 opens outwards through a membrane 124 which is held in position by means of a spring 126 working in compression. In the example shown in FIG. 4, the spring 126 is mounted around the filter 122. This membrane 124 allows the permeation gases and the water to be left while retaining the salts of sea water and other dusts in order to d 'avoid that these do not ipéRèti'gHt'à ¹ IGMtéi'ieui'elelB'ehBmhi'e'ele'lB ¹ seupapej ....................... .."not.

On the opposite side of the valve, the inlet chamber 106a communicates with the interior of the annular gap 108 formed between the internal surface of the internal ring 4 and the liner 12 via a pipe 128.

This pipe 128 is more precisely connected to a strainer 130 at its end opening into the gap 108. For example, the strainer comprises a plurality of through holes each having a diameter of 1mm.

The operation of this differential pressure valve is as follows. In production, a continuous flow of permeation gas diffuses through the lining 12 and in particular fills the annular gap 108 formed between the internal surface of the internal ring 4 of the junction pieces 2 and the lining. This permeation gas passes through the strainer 130 of each differential pressure valve and fills the inlet chamber 106a thereof. When the pressure inside ______________ inside the intake chamber exceeds the predetermined threshold pressure Ps, the piston 110 moves to the open position so as to allow gas to permeation. to — penetrate — dafls-the-chamber — discharge 106b, then to borrow the holes 118 of the calibration screw

112 to pass through the filter 122 and the osmotic membrane 124 and thus be evacuated outside into the ambient environment (i.e. sea water).

In the example described above, the junction piece in which the differential pressure valves according to the invention are positioned is a junction piece for a double-walled submarine pipe.

Of course, the differential pressure valves according to the invention can also be mounted on junction pieces for a submarine pipe with a single envelope, such as junction piece 2 ′ illustrated in perspective by FIG. 5.

In known manner, this junction piece 2 ′ is a piece of revolution centered on an axis of revolution XX. It comprises in particular a ring 4 'which is intended to be connected to the ends of two unit elements of the single-envelope pipe, ° this ring having a diameter corresponding substantially to the' diameter ...... of the element-tiwiteirea ¹ from the ^1st coating ..... seiF-lesqüieiB ..... ellcre'st ..............................

assembled by welding.

The junction piece 2 ′ also comprises an annular lining 12 ′ of plastic material which covers the internal surface of the ring 4 ′, this lining receiving the pressurized hydrocarbon fluids to be transported.

Finally, at the central part 10 ′ of the ring 4 ′, the junction piece 2 ′ further comprises a flange for limiting crushing propagation 14 ′ (“buckle arrestor”) which projects radially outwards . This flange 14 'thus forms a local excess thickness which serves to limit the risk of propagation of a crushing of the pipe under the effect of the instabilities of shape of the pipe sections caused by the external hydrostatic pressure of sea water. .

As for the junction piece described in connection with FIGS. 1 to 3, the crush propagation limitation flange 14 ′ of the junction piece 2 ′ is provided with differential pressure valves 100 ____________ according to the invention which are each intended to ensure the evacuation to the outside of permeation gases diffusing through the jacket______________________

—.12 '.— ------------- --- -------------------——

The arrangement within the flange 14 'and the characteristics of these differential pressure valves 100 are identical in all respects to those described previously in connection with FIGS. 1 to 4. I

Claims (10)

1. Differential pressure valve (100) for an underwater fluid transport pipe, the valve comprising: 2. Valve according to claim 1, wherein the holes (118) of the calibration screw (112) open outwardly through a ----------- filter - (- l-2-2 -) - intended-to-retain-impurities-coming-from-outside .----- 30 3. Valve according to claim 2, wherein the filter (122) opens outwardly through a membrane (124) held in position by means of a spring (126) working in compression. 4. Valve according to any one of claims 1 to 3, 35 in which the intake chamber (106a) communicates with the interior of the pipe via a pipe (128). ^ 5. The valve as claimed in claim 4, in which the pipe (128) opens at one end into the inlet chamber and opens at an opposite end inside the pipe via a strainer ( 130). b. Junction piece (2; 2J for sub-winding pipe for transporting fluids, comprising: ..... ⁼ a ring (4; 4 *) intended to be connected to 10 ¹ two éléiimyTfffflwiTOnJeTuiideiile, a flange (14; 14J of crushing propagation limitation projecting radially outward from the ring; and at least three differential pressure valves (100) according to any one of claims 1 to 5 , the valves being positioned radially within the flange. 5 a valve body (102) inside which is an internal chamber (106) opening on one side towards the pipe inside which there is an internal pressure Pi and opening on another side towards the outside where there is an outside pressure Pe: .............. a piston (110) arranged in the internal chamber so as to 1Ό ¹ .......... Dépa! Îa ^^ HH''Thmiibntt ^{, i,} iiili!. 'Riw.'' ^| g. ⁱ R ^{i ,,} Îiiien! lrei ^ l3i '& · ...... communicating with the interior of the pipe and a discharge chamber (106b) communicating with the exterior, the piston being movable between an open position in which the intake and discharge chambers communicate with each other and a closed position 15 in which the inlet and outlet chambers are sealed relative to one another; a calibration screw (112) screwed into the valve body and comprising a bore (114) inside which slides a rod (116) of the piston (110) and at least one bore (118) opening into the 20 discharge chamber and opening towards the outside; and a spring (120) positioned between the piston and the calibration screw, said spring being calibrated so as to keep the piston in the closed position below a predetermined threshold pressure inside the inlet chamber . _________________________ 7. Junction piece according to claim 6, in which the internal chamber (106) of each valve opens on one side inside the ring and opens on the other side towards the outside of the flange. 8. Junction piece according to claim 7, in which the internal chamber (106) of each valve opens on one side inside the ring through a lining (12; 12 ⁷ ) made of plastic material. . 25 9. Junction piece according to any one of claims 6 _______________ to 8, wherein the valves are regularly spaced from each other______________ around an axis of revolution (X-X) of the flange. 10. Junction piece (2) according to any one of claims 6 to 8, in which the ring (4) is an internal ring intended to be connected to the ends of two unitary elements of an internal pipe casing. , the junction piece further comprising an external ring (6) disposed around the internal ring being coaxial with it and intended to be connected to the ends of two unitary elements of an external pipe casing, the flange (14 ) projecting radially outward from the outer ring.