EP2452176A1

EP2452176A1 - Method for indestructibly testing internal pressure of hollow bodies, and test fixture

Info

Publication number: EP2452176A1
Application number: EP10730433A
Authority: EP
Inventors: Bernd Krause; Manuel Maier
Original assignee: Krause & Maier GbR
Current assignee: Krause & Maier GbR
Priority date: 2009-07-10
Filing date: 2010-07-01
Publication date: 2012-05-16
Also published as: EP2273252A1; WO2011003794A1

Abstract

The invention relates to a method for indestructibly testing internal pressure of hollow bodies (5), in particular pipes, by means of a test fluid (4) poured into the interior of the hollow body (5), wherein the test cycle per hollow body (5) to be tested is to be minimized, and the physical measures according to the invention are to ensure that the air present in the interior of the hollow body (5) is fully dispelled therefrom, in order to eliminate the risk of an accident. Said process flow as follows is characterized by the process steps placing the hollow body (5) in a basin (2) filled with the test fluid (4), - closing the two open end faces (9, 10) of the hollow body (5) by means of a pressure plate (16, 21) after the hollow body (5) is completely filled with test fluid (4), - generating an overpressure exerted by the test fluid (4) in the interior of the hollow body (5).

Description

Method for non-destructive internal pressure testing of hollow bodies and testing device

The invention relates to a method for internal pressure testing of hollow bodies according to the preamble of claim 1 and to a test device.

To promote large volume flows, for example natural gas or petroleum, over long distances, it is necessary to provide the largest possible sized hollow body, in particular pipes available. In order to determine whether the pipes have the required strength, it is necessary to check these hollow bodies to the required strength before they are used in pipelines. Such a test is usually a normalized test method. The hollow bodies to be tested must be subjected to an internal pressure over a certain period of time, by means of which the pipe wall is stretched to the required extent of the respective pipe material or beyond.

If a pressure drop occurs during the test procedure, the pipe has been overstretched before reaching the required yield strength and does not fulfill the required strength properties. Only when this test procedure is completed, the respective pipe can be installed in the pipeline.

The known test methods use a receiving frame in which the tube is inserted and closed at the two open end faces. One of the both the end faces sealing pressure plates has a filling line through which then the test liquid, preferably water, is pumped into the interior of the hollow body. The air present in the interior of the hollow body passes through an opening provided on the pressure plate pressure relief valve to the outside, so that after a certain time, the interior of the hollow body is completely filled with the test liquid.

In order to check the hollow body for strength, further test liquid is filled into the interior of the hollow body until the normalized test pressure is reached. This test pressure is maintained for a certain period of time. If the pipe proves to be stable, it can be installed in pipelines; otherwise, the pipe is not suitable for use in pipelines.

A disadvantage of this prior art has been found that the test cycle requires a considerable amount of time per hollow body to be tested, because first, the entire volume of the hollow body is to be filled with water or test liquid. Even if inflow conduits with a large cross-sectional area are used, it takes up to 10 minutes for the volume of the currently known hollow body to be enriched with test fluid; In the future, hollow bodies are used whose diameter is about twice as large as is previously possible for the known pipeline pipes.

Furthermore, such a delivery process is associated with a considerable expenditure of energy, since the low-pressure pump which supplies the test fluid has to convey the water with a very high volume flow. After filling the pipes, the test pressure is generated with a high-pressure pump with a relatively low volume flow. The service life of the pumps used are limited to that, so that after a certain period of operation, the pumps are replaced. The often still existing air in the specimen, also represents a very high safety risk, since at the existing test pressures of up to 100 MPa, the air is very strongly compressed, and thus very large energy is stored. When a damaged pipe bursts, the trapped air expands and releases the stored energy abruptly. When such accidents happen, the people possibly present in the vicinity of the hollow body are in mortal danger. Because of the explosive force, the pressure plates can be blown away, which have injured or even mortally wounded several times. Due to the enormous pressure loads inside the hollow body, such accidents can be avoided only by the fact that there are no air pockets either inside the hollow body. However, such a risk assessment is impossible; the control of such explosive forces therefore requires the complete venting of the hollow body. This process is time consuming and costly.

Furthermore, it is disadvantageous that the known test devices can be used practically only for a certain size of hollow bodies to be tested. The larger the volume of a hollow body, the longer the pump needs to fill the interior of the hollow body with test liquid and the more energy required for the operation of the pump.

It is therefore an object of the invention to provide a method for leak testing of hollow body and a test device for performing the method by which minimizes the test cycle per hollow bodies to be checked and is ensured by or by due to physical measures that the air in the interior of the hollow body escapes completely from this, in order to exclude the risk of accidents.

These objects are achieved by the features listed in the characterizing part of claim 1 and by the features of claim 8.

Further advantageous developments of the invention will become apparent from the dependent claims.

The fact that the hollow body or bodies is immersed in a tank filled with test fluid initially eliminates the technical necessity of filling the interior of the hollow body with test fluid by means of a low-pressure pump. It is particularly advantageous if the basin is in the form of an inclined plane. det, because this allows the tube to be immersed by means of gravity acting on this in the basin, so that only for pulling the tube, a corresponding drive is necessary. By using a counterweight, the energy for the drive can also be reduced. The elimination of the energy-intensive low-pressure pump results in great savings potential in terms of acquisition costs, maintenance and energy efficiency. Alone through the energy savings, the system pays for itself within a few years. Thus, a considerable energy saving is achieved by the test method according to the invention and the test device according to the invention.

Furthermore, by immersing the hollow body in the filled with test liquid tank ensures that the interior of the hollow body is fully evacuated, because the incoming test liquid pushes the air out of the pipe and only when it has completely escaped, the two open end faces of the tube sealed liquid-tight. Thus, the risk of accidents can be significantly minimized, because the sudden expansion of the air does not take place because air bubbles are not present in this, and the test liquid as a non-compressible medium can not store energy. The only energy to release is that stored in the elastic elongation of the tube. This is sufficiently attenuated by the water in the basin.

Furthermore, it is advantageous that the interior of the hollow body is filled up very quickly with test liquid, because by the conveying movements of the hollow body its inner volume is already filled with test liquid. In addition, the test liquid flows over the entire cross section of the hollow body into its interior, so that regardless of its size ratios, an enrichment with test liquid takes place within a short period of time.

In the drawing, an inventive embodiment is shown, which will be explained in more detail below. In detail shows:

FIG. 1a shows a testing device consisting of a filled with Prüfflüsεigkeit

Basin is immersed in a mounted on a chassis hollow body, in the initial state, FIG. 1b shows the test device according to FIG. 1a, while it is laid by a closing mechanism into a U-shaped receiving frame arranged in the basin;

FIG. 1 c shows the test device according to FIG. 1 b after the travel part and the hollow body fastened to it have reached the test position in the basin, in which the hollow body is closed in a liquid-tight manner by the closure mechanism,

FIG. 2a shows the closure mechanism according to FIG. 1c along the section line

H -Il,

FIG. 2 b shows a differently shaped basin shape according to FIG.

FIG. 3 shows a stop provided in the basin against which the hollow body rests in a liquid-tight manner along the section line IM-III according to FIG. 1c,

FIG. 4 shows the test device according to FIG. 1c along the section line IV-IV,

Figure 5 shows a different embodiment of the test device according to FIG. 1c, consisting of a lifting device, through which the hollow body enters into the

6a shows a different embodiment of the basin in which the testing device according to FIG. 5 is inserted,

FIG. 6b shows the basin according to FIG. 6a along the section line VIb-VIb, FIG. 7 shows the testing device according to FIG. 1c, in which the closure mechanism and the stop are assigned to the respective other open end side of the hollow body,

FIG. 8 a shows the test device according to FIG. 7 in the initial state, FIG. 8b shows the test device according to FIG. 7 during the test to be performed,

9 shows the call device according to FIG. 8b along the section line IX-IX and FIG

FIG. 10 shows the test device according to FIG. 9 along the section line X-X.

From FIGS. 1 a, 1 b and 1 c, the method sequence for filling a hollow body 5 in the form of a tube with test liquid 4 in a test device 1 can first be taken. The test device 1 comprises a basin 2, in which the test liquid 4 is filled. The basin 2 opens into a ramp 3 extending from the horizontal sloping and consists of a pool floor 34, the angle of inclination of which is identical to the ramp 3 and of a pool edge 35.

In the ramp 3 and the pelvic floor 34 two parallel aligned rails 36 are installed, on which a chassis 6 is placed, which is connected via a cable 7 with a motor 8. By means of the chassis 6, the tubes 5 are supported laterally so that they can not roll out of the chassis 6. By the motor 8, the chassis 6 is moved in the direction of the basin 2. Once the chassis 6 has reached the ramp 3, this is pulled by the force acting on the chassis 6 and the tube 5 gravity in the direction of the basin 2. The tube 5 has two open end faces 9 and 10. The front side 9 facing the basin 2 reaches the test liquid 4 first and dives into it, so that, as can be seen in particular from FIG. 1 b, the interior of the tube 5 is filled uniformly and over the entire internal cross section with test liquid 4, without the need for additional aids, such as feed pumps or the like, are required. The air present in the interior of the tube 5 escapes from the front side facing away from the basin 2. This immersion process thus first ensures that the air is completely evacuated from the interior of the tube 5 when it is completely in the test liquid chain 4 is immersed. Furthermore, for the evacuation of the interior of the pipe

5 no additional energy needed to drive a feed pump.

The test device 1 furthermore consists of a receiving device 11 arranged in the pelvis 2 and firmly mounted thereon. The receiving device 11 consists of two legs 12 and 13 which run parallel to one another and are spaced apart from each other and which are fixed to one another via a web 14. The cross-sectional contour of the receiving mast 11 is thus configured U-shaped. The open side of the receiving rack 11 faces the ramp 3 and the chassis 6 so that it can be pushed into the receiving rack 11 together with the tube mounted on the chassis 6. In this state, which is shown in FIG. 1c, the tube 5 is completely filled with test liquid 4. Consequently, the two open end faces 9 and 10 can be closed liquid-tight. This is done in such a way that the chassis 6 and thus the tube 5, immediately before it touches a formed on the web 14 stop 15 is closed with a pressure plate 16. The stop 15 is the tube 5 and the chassis

6 facing. Consequently, the chassis 6 is lowered by the cable 7. Between the open end face 9 of the tube 5 and the stop 15 of the receiving mast 11 there is the pressure plate 16 which is used for changing from above. The contour of the pressure plate 16 is adapted to the contour and the diameter of the tube 9 and corresponds with this. In the region of the wall of the tube 5 16 plastic or metal seals are formed on the pressure plate, which rest on the wall of the tube 5. The pressure plate 16 is attached to a pulling device 17 which is driven by a motor 18. Consequently, the pressure plate 16 can be raised or lowered.

Once the pressure plate 16 is aligned in the correct position with respect to the open end face 9 of the tube 5, the chassis 6 is moved in the direction of the stop 15, so that due to the prevailing gravity of the tube 5 an Anεεεε force acts on the pressure plate 16, the Accordingly, between the open end face 9 and the stopper 15 is held clamped. In the two legs 12 and 13 of the receiving frame 11, a plurality of grooves 19 are incorporated, which are aligned with each other. The grooves 19 extend perpendicular to the longitudinal axis 33 of the tube 5 and are open in the direction of the surface of the test liquid 4. Namely, the lengths of the tubes 5 to be checked can be dimensioned differently so that different lengths of tubes 5 lie in a different end position relative to the receiving frame 11. This end position is determined by the open end face 10 of the tube 5, so that a closure mechanism 20, which is formed like a gouillotine, in the region of the open end face 10 is arranged.

The closure mechanism 20 consists of a frame 26, on the laterally projecting two bolts 27 are formed. Therefore, as soon as the shutter mechanism 20 is lowered, the bolts 27 are inserted into the grooves 19 which are closest to the open end face 10. This can be seen in FIG. The shutter mechanism 20 can thus be moved.

The shutter mechanism 20 further includes four pressure pistons 22 which are supported on the frame 26 and by which a pressure plate 21 is held. As soon as the pressure plate 21 extends in the region of the open end face 10, a contact force will be generated via a pump 23 in operative connection with the pressure piston 22, by means of which the pressure plate 21 is pressed onto the open front side 10 of the tube 5. The four pressure pistons can thereby be replaced by any desired number of pressure pistons 22, for example one, two or the like. In the pressure plate 21, a test line 24 is incorporated, through which the test liquid 4 is pressed by a pump 25 into the interior of the tube 5, as soon as the two open end faces 9 and 10 are sealed liquid-tight. By the pump 25, an overpressure is thus generated in the interior of the tube 5, which generates a load on the tube wall to the yield point, namely up to 100 MPa, depending on the pipe diameters and their wall thicknesses. The pressure is maintained for a certain period of time. If the pressure drops, the tube has been stretched beyond the yield point and thus faulty. Once the shutter mechanism 20 is inserted over the two bolts 27 in the grooves 19 of the legs 12 or 13 of the receiving frame 11, creates a completely closed rechteckfömniger frame. Accordingly, the closing mechanism 20 is form-fittingly connected to the receiving frame 11 and the pressure forces acting in the interior of the tube 5 are absorbed by the receiving part 11.

Furthermore, it can be seen from FIG. 4 that on the pressure plate 16 or 21, two retaining bolts 31 are formed, which serve as locking aids for the respective pressure plate 16 and 21, respectively, because the pressure plates 16 or 21 are U-shaped Accommodated receiving pockets 32, in which the retaining bolts dive 31 and thus additionally fix the respective pressure plate 16 and 21 and lead. In FIG. 2 b, in contrast to FIG. 2 a, the closure mechanism 20, which can be moved in the direction of the open end face 10 via rollers 50 guided in the rails 39, in order to position it as close as possible in the region of the open end face 10 the pool edge 35 is moved, so that the interior of the basin 2 can be made substantially smaller. FIG. 5 shows another possibility of how the tube 5 can be immersed in the basin 2. For this purpose, a lifting device 37 in the form of a gantry crane is placed on the pool edge 35. On a frame 38 of the lifting device 37 movable hooks 40 are provided, through which the tube 5 is held inclined in the direction of the test liquid 4. Thus, the tube 5 obliquely immersed in the test liquid 4, so that the existing air inside the tube 5 escapes faster than when the tube 5 is moved parallel to the surface of the Prüfflüssigkeit 4. The pelvic floor 34 is horizontal; an inclination of the pelvic floor 34 is not required in this embodiment. The pelvic floor 34 is now assigned to the chassis 6, on which the tube 5 is placed by the lifting device 37. Consequently, the tube 5 can be moved slightly inside the pelvis 2 to the right or left to press this through the shutter mechanism 20 on the stop 15 and thus on the pressure plate 16. In the figures 6a and 6b, a further embodiment of the test device 1 is shown, because now two tubes 5 are simultaneously introduced into the interior of the basin 2 and if this is desired by a user of the test device 1, should the Tubes 5 surrounding test liquid 4 are pumped. For this purpose, two receiving tanks 51 and 52 are located laterally next to the basin 2, which run at different heights. In this case, the receiving basin 51 is the lowest and the receiving basin 52 the highest, so that the basin 2 with the test liquid 4 extends between these two receiving basins 51 and 52. As soon as the tubes 5 are inserted into the basin 2 and these have been completely filled with test liquid 4, the test liquid 4 is discharged from the basin 2 into the receiving basin 51. For this purpose, no pump is necessary, because due to gravity, the test liquid flows 4 without further aids in the receiving basin 51st

During the Prüfzyklusses for the tubes 5, the test liquid 4 is conveyed from the receiving basin 51 into the receiving basin 52 by means of a pump. As soon as the test cycle for the tubes 5 has been completed, the two pressure plates 16 and 21 are removed from the open end faces 9 and 10, so that the water present in the interior of the tubes 5 flows back into the basin 2 from these.

While two new tubes 5 to be tested dip into the basin 2, the test liquid 4 is conducted from the receptacle 52 into the basin 2, so that it is again completely filled with test liquid 4.

In the figures 7, 8a, 8b, 9 and 10, a different type of design of the test device 1 can be seen, because now the shutter mechanism 20 is to be provided stationary in the interior of the basin 2. For this purpose, the four Druckkoiben 22 are fixedly connected to the web 14 of the receiving frame 11. The pressure plate 21 is used by means of the cable 17 and the motor 18 to cover the open end face 9 from above.

To make a positive connection between the U-shaped receiving frame 11 and the now the open end 10 associated stop 15, so a To create rectangular closed box frame, are formed on the two end faces of the legs 12 and 13 Haitezapfen 41, which have two different diameters. The side of the retaining pin 41, which is associated with the stop 15, in this case has the larger diameter than the diameter of the respective leg 12 and 13 facing portion of the retaining pin 41, so that in this way a groove 42 and a perpendicular to the longitudinal axis 33 of the Tube 5 extending Anschlagsfiäche 43 is formed.

As can be seen in particular from FIGS. 9 and 10, the stop 15 is designed in the form of a plate which enters the groove 42 of the retaining pins 41 from above and is thus held by the stop 43 as soon as the pressure pistons 22 a exert a contact force generated by the pump 23. Consequently, the tube 5 between the pressure plate 21 and the pressure plate 16 is held clamped by the pressure piston 22 and the stop 15 and the pressure force acting inside the tube 5 can be absorbed by the receiving frame 11; other positive connections can also be used ,

Claims

claims

1. A method for non-destructive internal pressure testing of hollow bodies (5), in particular of tubes, by means of a in the interior of the hollow body (5) filled test liquid (4), characterized by £ the following process steps:

- introducing the hollow body (5) into a filled with the test liquid (4) basin (2),

Closing the two open end faces (9, 10) of the respective hollow body (5) with a pressure plate (16, 21) after the hollow body (5) has been completely filled with test liquid (4),

- Generating an exerted by the test liquid (4) overpressure inside the hollow body (5).

2. The method according to claim 1, characterized in that after filling of the hollow body (5), the test liquid (4) from the basin (2) is derived.

3. The method according to claim 1, characterized in that the respective hollow body (5) by means of a chassis (6) via an in

2) inclined ramp (3) is inserted into this, or that the respective hollow body (5) by means of a lifting device (37), preferably by means of a crane, in the basin (2), preferably in the direction of the test liquid ( 4) inclined, immersed.

4. The method according to claim 1, characterized in that on one of the two pressure plates (16 or 21) a pump (25) is arranged, through which a test line incorporated therein (24) into the interior of the hollow body (5) the test liquid (4) is permanently pumped to generate the overpressure during the test cycle.

5. The method according to any one of the preceding claims, characterized in that in the basin (2) a plurality of hollow bodies (5) at the same time or temporally offset from one another in the manner of a conveyor belt are used and that the

Order of the test steps coordinated with each other in each of the hollow body (5) inserted into the basin (2) is performed.

6. The method according to claim 1, characterized in that one of the pressure plates (16 or 21) between one of the two end faces (9 or 10) of the hollow body (5) and one in the basin (2) used Receiving frame (11) inserted from above or laterally to this and by the receiving frame (11) and the hollow body (5) is held clamped that the other pressure plate (16 or 21) by means of a Verschlussme- chanismusses (20) in the region of the second end face (9 or 10) of the hollow body (5) is arranged and that the pressure plate (16 or 21) then by at least one attached to the closure mechanism (20) and parallel to the longitudinal axis (33) of the hollow body (5) aligned pressure piston ( 22) is pressed onto the open end face (9 or 10) of the hollow body (5).

7. test device (1) consisting of a test liquid (4) filled basin (2) in which a U-shaped receiving frame (11) is arranged, from a conveyor (6, 7, 8) or lifting device ( 37), through which one or more hollow bodies (5) is / are inserted into the receiving frame (11), with one integrally formed on the web (14) of the receiving frame (11) and the first open end face (9) of the hollow body (5 ) facing stop (15) through which the end face (9) by means of a pressure plate (16) is liquid-tightly closed during the test condition, with a closure mechanism (20) through which the second open end face (10) of the hollow body (5) in the test state by means of a pressure plate (21) is liquid-tightly sealed and with the receiving frame (11) is positively connected, and with a pump (25) through which by the stop (15) or by the closure mechanism (20) test liquid (4) in the Interior of the H ohlkörpers (5) is filled to generate an overpressure.

8. testing device according to claim 7, characterized in that the basin (2) at least one in the direction of the pelvic floor (34) inclined ramp (3) is assigned and that each hollow body (5) is mounted on a chassis (6), by this on the ramp (3) in the basin (2) can be inserted.

9. Apparatus according to claim 8, characterized in that the pelvic floor (34) is aligned inclined from the horizontal and that the ramp (3) with the pelvic floor (34) is connected.

10. The device according to claim 7, characterized in that each hollow body (5) by means of a lifting device (37), preferably a crane, in or out of the basin (2) is moved.

11. Testing device according to one of claims 7 to 10, characterized in that the respective end faces (9, 10) of the hollow body (5) occlusive

Pressure plate (16, 21) with the diameters and / or the inner contours of the hollow body (5) correspond.

12. Test device according to claim 7, characterized in that the stop (15) as a pressure piston (22) and the closure mechanism (20) as a stop (15) are formed and that by the or the pressure piston (22) of the hollow body (5) is displaced in the direction of the stop (15) and pressed onto this liquid-tight.

13. Testing device according to claim 7, characterized in that the pressure plate (21) on a frame (26) of the Verschlussme- chanismusses (20), preferably in the vertical direction, is movably held.

14. Test device according to claim 7, characterized in that on the frame (26) of the closure mechanism (20) two bolts (27) are formed, which are aligned with each other and perpendicular from the frame (26) in the direction of the two legs (12 , 13) of the receiving rack (11),

and that the bolts (27) engage positively in a groove (19) incorporated in the legs (12, 13) in the mounted state of the closure mechanism (20) on the receiving frame (11).