FR2625012A1 - METHOD AND DEVICE FOR REPRODUCING THE CONDITIONS NECESSARY FOR REALIZING A WELDING OPERATION ON AN IN-SERVICE DRIVEN IN WHICH CIRCULATES A FLUID - Google Patents

Abstract

The subject of the present invention is a method and a device for reproducing the conditions necessary for carrying out a welding operation on an immersed pipe in service in which a fluid circulates; a test bench 1 composed of two coaxial tubes 16/17 delimiting an annular space 18 in which a helicodal wall is wound with a constant pitch is placed in a hyperbaric chamber 2 and a turbulent flow d is established in this space 18 a fluid whose temperature, pressure and flow rate are chosen to obtain a transfer of heat through the external wall 16 of bench 1 comparable to that obtained by the circulation of said fluid in the submerged pipe in service. Finds its application particularly in the field of underwater work.

Description

Method and device for reproducing the conditions necessary for

  performing a welding operation on a submerged pipe in service in which

circulates a fluid.

  The present invention relates to a method and a device for reproducing the conditions necessary to carry out a welding operation on a submerged pipe in service in which circulates

a fluid.

  The technical field of the invention is that of the apparatus

  their application in the field of underwater work.

  Currently to reproduce the conditions necessary to carry out a welding operation on a pipe in which a fluid circulates, a test bench consisting of a pipe of which a section has the same characteristics as those of said pipe, which test bench, is made. performs a loop in which is circulated the same fluid that circulates in the pipe in service, for example oil or a gas and is obtained in the atmosphere, the conditions of heat transfer through the

  wall of the pipe in use in which circulates said fluid.

  Such pipes can reach large diameters, of the order of one meter, it is conceivable that such a test bench is cofuteux to implement and is relatively bulky which for example forbidden to use it in a hyperbaric chamber classic to reproduce the welding conditions to be performed on a pipe

immersed in service.

  The present invention aims to remedy these disadvantages.

  The objective to be achieved is a test bench employing a method and a device for reproducing, under the pressure of the bottom, the conditions necessary to carry out a welding operation on a submerged pipe in service in which circulates.

oil or gas.

  This objective is achieved by the method according to the invention according to which: there is disposed in a hyperbaric chamber a first section of pipe having the same characteristics as those of the pipe in service; a second pipe section of the same length as said first section and of an external diameter less than the internal diameter of said first section, so that the first and second pipe sections are coaxial and delimit between them an annular space; in said annular space there are means for generating a turbulent flow of a fluid; the two ends of said annular space are closed off; an inlet orifice at one end of said annular space is allowed to admit a fluid under pressure and a

  circulation of this fluid in the turbulent state in said annular space;

  the circulating fluid is collected by an outlet orifice situated at the other end of said annular space and said fluid is recycled; the conditions such that the distance between the walls of the two pipe sections, said means generating a turbulent flow of the fluid, the temperature, the pressure and the flow rate of the fluid are chosen to obtain a heat transfer through the wall; said first driving section comparable to that obtained by the circulation of said fluid in the pipe in

submerged service.

  According to the process, the following formula is applied: P = H (T ducting - fluid T) in which P is the heating power and H is an exchange coefficient, which formula is applied as follows: PH '(T test section - T circulating fluid in the bank), the characteristics of the fluid circulating in the bank and its temperature make it possible to deduce the average velocity of said fluid and from the speed thus deduced and the flow rate of said fluid, a passage section, that is to say the annular space between the two sections of pipe that make up the bench and the pitch of the helical wall which constitutes the means

  generators of a turbulent fluid flow.

  The objective is also achieved by the device according to the invention, which comprises in combination: a hyperbaric chamber in which is placed a test bench composed of:

  - a first section of driving having the same characteristics

  the same as driving in service; a second pipe section, of the same length as said first pipe section, which second pipe section has an outside diameter less than the internal diameter of said first section, said first and second pipe sections being coaxial and delimiting between them a annular space; means generating a turbulent flow of a fluid located in said annular space, which comprises, at its ends, closure walls; an inlet for a fluid under pressure located at one end of said annular space and an outlet orifice at its other end, and means for circulating said fluid in said annular space to adapt and control its flow rate; , its temperature and its pressure so as to obtain a heat transfer through the wall of said first pipe section comparable to that obtained by the circulation of the fluid in the

submerged pipe in service.

  According to one embodiment, the generating means of the turbulent flow of the pressurized fluid are constituted by a helical wall extending along a length of the annular space, which wall joins tightly. the inner face of said first pipe section and the outer face of said second section. Said helicoidal wall consists of a flat iron wound helically around said second pipe section to which it is attached, which flat iron delimits with the inner face of said

  first section a space filled by a seal.

  Said seal consists of a bead placed in contact with the inner face of said first pipe section and two lips which overlap said flat iron, which gasket is fixed to the flat iron by

  bonding and is made of thermal silicone.

  The inlet of the fluid under pressure is attached to the wall of said second pipe section and the outlet port of said

  fluid is attached to the wall of said first section.

  According to the invention, said device further comprises a tarpaulin containing said fluid from which the "go" circuit of the fluid, which circuit comprises a pump for the circulation and pressure of said fluid from the tarpaulin, a flow meter, a thermometer and a manometer, which circuit leads to a passage of _______ es k__t. A-1i. And a conduit extending from said wall passage to the inlet port of said second pipe section and the "return" circuit to the tarpaulin comprises a pipe extending from the outlet port secured to said first pipe section; pipe section at a wall passage of the hyperbaric chamber, which circuit having, from said wall passage, a thermomètreet a valve for adjusting and stopping the fluid stream back to the tarpaulin. Said helical wall is orthogonal

said driving sections.

  The result of the invention is the implementation of the conditions and means for optimally performing a welding operation on a submerged pipe in service and in

which circulates a fluid.

  The advantages of the invention lie, on the one hand, in the operating conditions of the test bench in a hyperbaric enclosure, the test being carried out at the bottom pressure where the submerged service pipe is located on which the welding operations must be carried out and secondly at the cost of the installation which is significantly lower than that of the test benches currently used and also the ease of implementation

  of the process with a material of great simplicity.

  Other advantages and characteristics of the invention

  will come out again on reading the following description of a

  embodiment of a test bench given by way of example, with reference to the appended drawing in which: - Figure 1 is a schematic cross sectional view of a hyperbaric chamber in which is arranged a test bench according to the invention and on which are represented the control apparatus of the bench schematically illustrated outside the hyperbaric chamber; - Figure 2 is a longitudinal sectional view of a test bench similar to that of Figure 1; - Figure 3 is a sectional view along line III III of Figure 1; FIG. 4 is a view in partial section on a larger scale illustrating the implementation of the helical wall which extends in the annular space existing between the two sections of

coaxial pipes.

  In order to reproduce on a pipe section the conditions of a submerged operating pipe that are decisive for a welding operation, that is to say: the internal pressure and the flow of the gas or oil, it is realized, according to the invention a flow of fluid for example water between the pipe section to be studied and a second pipe section coaxial with said first section and on which second section is welded a helical wall. The space between the two pipe sections, the pitch of the helical wall, the temperature, the pressure and the water flow rate are chosen to establish a turbulent flow imposing a transfer of heat through the wall of said first section of water. conduct comparable to that obtained by the circulation of gas or oil in the pipeline

in submerged service.

  Said first pipe section, which constitutes the outer shell of the test bench, is constituted by a section having similar or identical characteristics to those of the submerged service pipe (internal diameter, wall thickness and

grade steel).

  The length of the bench is of course dictated by the maximum congestion allowed in the hyperbaric chamber where the tests take place. The outer diameter of the second pipe section disposed coaxially inside said first section and the pitch of the helical wall which winds along the length of the bench around said second pipe section are defined as follows: the characteristics of the pipe in service of the fluid conveyed make it possible to calculate the heating power necessary to obtain the temperature of the wall which it is necessary to reach for

the welding operation.

  The following formula is applied: P = H (T channeling - fluid T) in which P-is

  the heating capacity and H an exchange coefficient.

  For example, the exchange coefficient used during the tests carried out is as follows: H = X0.023 XPV0.8 t p4 X = Thermal conductivity D = 4S hydraulic diameter p P = density V = speed = dynamic viscosity Cp = specific heat Using the same heating power on the test bench as on the pipe in service, the objective is to find

  the same temperatures in the welding zone.

  For this it is written that the heat flow dissipated through the wall of the pipe in service is equal to the heat flow dissipated through the wall of said first pipe section which constitutes the shell of the bench. :

  P = H '(T test section - T water).

  The characteristics of the water and its temperature allow

  to deduce the average speed of the water.

  Knowing this vitse, we define a passage section (that is to say the annular space between the two pipe sections that make up the bench and the pitch of the helical wall) to obtain a turbulent water flow of the order of 8m3 / s. We make sure that

  this passage section allows a homogeneous flow.

  Of course, the thickness of the second section of inner pipe and the two end plates is defined to withstand the internal pressure of the bench, this pressure may be necessary

  to avoid boiling water.

  One embodiment of the device according to the invention for implementing said method is given schematically in the

Figure 1 of the drawing.

  The test bench 1, which will be described later, is disposed inside a hyperbaric chamber 2 in which there is pressure

  identical to that of the bottom where is the driving in service.

  The circulation of the water for the implementation of the test is carried out by the following circuit: the water is pumped into a pond or tank 3, by a pump 4, inserted into a tubing 5 on which are placed: a flow meter 6, a thermometer 7 and a pressure gauge 8. The tubing 5 leads to a wall passage 9 of the hyperbaric chamber 2. The water is directed from said wall passage 9 to the orifice

  input of the bench by means of a tubular for example flexible 10.

  After the water has circulated in the bank 1 in the turbulent state, it is recycled in the circuit. Another flexible tubing 11 is attached to the outlet-of the bench and extends to a second wall passage 12 of the enclosure 2.The tubing 13 conducts water to the tank 3 on which tubing are placed a thermometer 14 and a

regulating and stopping valve 15.

  Figures 2 to 4 show in more detail the construction of

  test bench 1 for carrying out the method according to the invention. As shown in FIGS. 2 and 3, said test bench consists of a first pipe section 16 having the

  same characteristics as those of the submerged service line.

  In this first section and coaxially thereto, is placed a second pipe section 15. As can be seen in the drawing, this second section is of an external diameter substantially smaller than the internal diameter of said first section 16 so that that a space

  annular 18 is reserved between the two sections 16/17.

  In this annular space is wound helically a wall 19 over the entire length of the bench, the space between the two sections 16/17 and the pitch of the propeller 19 are defined such that:

been exposed above.

  The wall 19 (FIG. 4) consists of a flat iron 19a orthogonal to the section of the central duct 17 and to the envelope 16. For reasons of ease of manufacture of the bench, the flat iron 19a is of a height less than the space 18 which separates the two sections 16/17. The imperviousness of the helicoidal wall 19 is obtained by means of a seal 19b, consisting of a bead 19b1 bearing on the inner face 16a of the wall of said first pipe section 16 and is mounted astride the flat iron. 19a. The seal 19b thus comprises two lips 19b2 / 19b3 substantially parallel to each other and of the same length and its attachment to the flat iron is obtained by gluing. Preferably, this seal is chosen in the

  family of thermal silicone joints.

  The annular space 18 is closed at both ends of the bench by walls-20/21 welded to said pipe sections 16/17, which walls protrude around said sections and are of a square outline. They are recessed in their central part extending to the inner periphery of the pipe section 17 to allow

  to access the interior of it.

  The bench also comprises a water inlet orifice 22, fixed to the wall of the second pipe section 17 and an outlet orifice 23, fixed to the wall of the first pipe section 16. These orifices are reserved in bosses tapped in their center to allow the connection of the pipes 10/11 of the hydraulic circuit. Unlike the bench shown in Figure 1, that of

  Figures 2 and 3 comprises a stitching 24 formed by a welded ferrule.

  at section 16 during the weld test in the middle section

of the bench.

  Of course, without departing from the scope of the invention, the parts which have just been described by way of example may be replaced by those skilled in the art by equivalent parts fulfilling the same function.

Claims (10)

  A method for reproducing the conditions necessary for performing a welding operation on a submerged pipe in service, in which a fluid circulates, characterized by the following operations: a first pipe section is provided in a hyperbaric enclosure (2) ( 16) having the same characteristics as those used in service; a second pipe section (17) of the same length as said first section and of an external diameter smaller than the inner diameter of said first section is placed inside said first pipe section (16), so that the first and second pipe sections (16/17) are coaxial and delimit between them an annular space (18); in the annular space (18) there are means (19) generating a turbulent flow of a fluid; the two ends of said annular space (18) are closed off; an inlet orifice (22) located at one end of said annular space (18) is admitted by means of a pressurized fluid and a circulation of this fluid in the turbulent state is established in said annular space; the circulating fluid is collected by an outlet orifice (23) located at the other end of said annular space (18) and said fluid is recycled; the conditions such as the distance between the walls of the two pipe sections (16/17), said means (19) generating a turbulent flow of the fluid, the temperature (7/14), the pressure (8) and the flow (6) of the fluid are chosen to obtain a heat transfer through the wall of said first pipe section (16) comparable to that obtained by the circulation of said fluid   in the pipe in submerged service.   2. Method according to claim 1, wherein the following formula is applied: PH (T pipe - fluid T) in which P is the heating capacity and H an exchange coefficient, which formula is applied as follows: P = H '(T test section - T circulating fluid in the bank) the characteristics of the fluid circulating in the bank and its temperature to deduce the mean velocity of said fluid, characterized in that the means generating a flow turbulent are constituted by a helical wall (19) and in that from the speed thus deduced and the flow rate of said fluid, a passage section is defined, that is to say the annular space (18). ) between the two pipe sections (16/17) which make up the bench (1) and the pitch of the wall (19)   helically, to obtain turbulent fluid flow.   3. Device for reproducing the characteristics necessary for carrying out a welding operation on a submerged pipe in service in which a fluid circulates, characterized in that it comprises, in combination: a hyperbaric enclosure (2) in which is placed a test bench (1) composed of: - a first section of pipe (16) having the same characteristics as those of the pipe in service; a second pipe section (17) of the same length as said first pipe section (16), which second pipe section (17) has an outside diameter less than the internal diameter of said first section, said first and second sections of pipe conduct - (16/17) being coaxial and delimiting between them an annular space 18; - means (19) generating a turbulent flow of a fluid located in said annular space (18) which has, at its ends, closure walls (20/21); an inlet (22) for entering a pressurized fluid located at one end of said annular space (16) and an outlet (23) at its other end; and means (4) for circulating said fluid in said annular space (18) to adapt and control its flow rate (6/15), its temperature (7/14) and its pressure (8) so as to obtain a transfer of heat through the wall of said first pipe section comparable to that obtained by the circulation of fluid in the submerged pipe in service.   4. Device according to claim 3, characterized in that the generating means of the turbulent flow of the fluid under pressure are constituted by a helical wall (19) extending at a constant pitch over the length of the annular space (18). ), which wall sealingly joins the inner face (16a) of said first pipe section (16) and the outer face of said second section (17).   5. Device according to claim 4, characterized in that said helical wall (19) consists of a flat iron (19a) wound helically around said second pipe section (17) to which it is attached, which flat iron delimits with the inner face (16a) of said first section (16) a space filled by a seal (19b). 6. Device according to claim 5, characterized in that said seal (19b) consists of a bead (19bl) brought into contact with the inner face (16a) of said first pipe section (16) and two lips (19b2). / 19b3) which overlap said flat iron (19a),   which seal (19b) is attached to the flat iron (19a) by gluing.   7. Device according to any one of claims 5 or   6, characterized in that said seal (16b) is made of silicone thermal.   8. Device according to claim 3, characterized in that the inlet (22) for entry of the fluid under pressure is fixed to the wall of said second pipe section (17) and that the outlet orifice   (23) of said fluid is attached to the wall of said first section (16).   9. Device according to any one of claims 3 to   8, characterized in that it comprises a cover containing said fluid (3) from which the "go" circuit of the fluid, which circuit comprises a pump (4) for the circulation and pressure of said fluid from the tarpaulin , a flow meter (6), a thermometer (7) and a pressure gauge (8), which circuit leads to a wall passage   sealed (9) reserved in the wall of the hyperbaric chamber (2) and a.   conduit (10) extending from said wall passage (9) to the inlet (22) of said second pipe section (17) and the "return" circuit to the tarpaulin (3) comprises a pipe (11) extending from the outlet (23) attached to said first pipe section (16) to. a wall passage (12) of the hyperbaric chamber (2), which circuit has, from said wall passage (12), a thermometer (14) and a valve (15) for adjusting and stopping the vein of fluid back to the tarpaulin.   10. Device according to any one of claims 4 -   or 5, characterized in that said helical wall (19) is   orthogonal to said pipe sections (16/17).