A device and method for detecting the corrosion rate of a pipeline

Abstract

The application provides a pipeline corrosion rate detection device and a detection method. The pipeline corrosion rate detection device comprises a test piece and a frame body. The material of the test piece is the same as that of the pipeline. The frame body comprises a fixed beam. The test piece is detachably connected to the fixed beam. The fixed beam and the test piece are arranged in a space in communication with the inner cavity of the pipeline, so that the test piece can be located in the same fluid environment as the inner part of the pipeline. The structure is simple, the operation is convenient, the corrosion rate of the pipeline can be accurately predicted, and the pipeline can be repaired or replaced before failure.

Description

TECHNICAL FIELD

[0001] The present application relates to the oil and gas exploitation technical field, and particularly relates to a pipeline corrosion rate detection device and detection method. BACKGROUND

[0002] In the oil and gas exploitation, the inner wall of the pipeline directly contacts with the conveying medium, which contains various corrosive impurities, such as dissolved oxygen, carbon dioxide, sulfur oxide, sulfate-reducing bacteria and chloride ions, etc. Under the combined action of temperature, pressure, flow rate and alternating stress, the inner wall of the pipeline is corroded more seriously. Therefore, it is necessary to predict the inner corrosion rate of the high-pressure water injection pipeline, so as to repair or replace the pipeline before the pipeline fails.

[0003] At present, many scholars and technical personnel have made some related explorations on the pipeline inner corrosion rate prediction method. However, the interaction between the corrosive factors of the inner wall of the pipeline is very complex, and it is difficult to control all factor changes in the experimental process, so that the experimental results are relatively dispersive, and it is difficult to express the relationship between them by using accurate mathematical expressions. SUMMARY

[0004] The purpose of the present application is to provide a pipeline corrosion rate detection device and detection method with simple structure and convenient operation, which can accurately predict the corrosion rate of the pipeline, so that the pipeline can be repaired or replaced before it fails.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is:

[0006] A pipeline corrosion rate detection device, comprising: a test piece and a frame body;

[0007] The material of the test piece is the same as that of the pipeline, the frame body comprises a fixed beam, the test piece is detachably connected to the fixed beam, and the fixed beam and the test piece are arranged in a space communicating with the inner cavity of the pipeline, so that the test piece can be located in the same fluid environment as the inside of the pipeline.

[0008] Preferably, it further comprises a mounting bolt and a mounting nut;

[0009] The first mounting through hole is arranged on the test piece, the second mounting through hole is arranged on the fixed beam, the mounting bolt passes through the first mounting through hole and the second mounting through hole in sequence, and is threadedly connected to the mounting nut, so as to connect the test piece to the fixed beam.

[0010] Preferably, it further comprises a separation gasket;

[0011] The spacer is arranged between the test piece and the fixed beam to form a gap between the test piece and the fixed beam along the axis of the mounting bolt.

[0012] Preferably, the number of test pieces is at least two, including at least one first test piece and at least one second test piece.

[0013] The first test piece is in the shape of a rectangular body, and the six end faces of the first test piece are smooth planes.

[0014] The second test piece is in the shape of a rectangular body, and a cylindrical groove is arranged on one of the end faces.

[0015] Preferably, the number of second test pieces is at least two, and the diameters and / or depths of the grooves on any two second test pieces are different.

[0016] Preferably, a pipe body is further included.

[0017] The pipe body can be arranged on the flow passage of the pipeline, so that the fluid flowing through the pipeline can flow through the pipe body at the same time.

[0018] The frame body and the test piece are arranged in the inner cavity of the pipe body, and the frame body further includes a connecting column, and the fixed beam is fixedly connected to the inner wall of the pipe body through the connecting column.

[0019] A pipeline corrosion rate detection method using the pipeline corrosion rate detection device with any of the technical features above, including the steps of:

[0020] S100, weighing the test piece and recording the initial weight G1 of the test piece;

[0021] S200, connecting the test piece to the fixed beam;

[0022] S300, placing the fixed beam with the test piece in a space communicating with the inner cavity of the pipeline, and recording the placement time T of the test piece in the space;

[0023] S400, taking out the fixed beam with the test piece from the space communicating with the inner cavity of the pipeline;

[0024] S500, disassembling the test piece from the fixed beam, weighing it to obtain the post-test weight G2 of the test piece, and measuring the depth H of the corrosion recess on the test piece;

[0025] S600, calculating the overall corrosion rate V1 and the pitting corrosion rate V2;

[0026] V1=C×{(G1-G2) / S×T×ρ}, C is a conversion coefficient, S is the surface area of the test piece, and p is the density of the test piece.

[0027] V2=H / T.

[0028] Preferably, after the test piece is detached from the fixed beam in step S500, the test piece is cleaned, and then the test piece is weighed and the depth of the corrosion pits is measured.

[0029] Preferably, the measurement of the corrosion depth H on the test piece includes:

[0030] The depths of the n corrosion pits on the surface of the test piece are measured respectively to obtain a first corrosion depth H1, a second corrosion depth H2,..., and an n-th corrosion depth Hn, and H=(H1+H2+...+Hn) / n, wherein n is an integer greater than 1.

[0031] Preferably, the pipeline corrosion rate detection device comprises a pipe body, and the frame body further comprises a connecting column.

[0032] In step S100, the fixed beam connected with the test piece is fixedly connected to the inner wall of the pipe body through the connecting column, and then the pipe body is installed on the flow path of the pipeline.

[0033] The pipeline corrosion rate detection device of the present application can accurately predict the corrosion rate of the pipeline by arranging the fixed beam and the test piece in the space communicating with the inner cavity of the pipeline, so that the test piece can be located in the same fluid environment as the inner part of the pipeline, thereby enabling the pipeline to be repaired or replaced before failure. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a structural schematic view of the pipeline corrosion rate detection device in Example One.

[0035] Figure 2 It is an enlarged schematic view of I part in Figure 1

[0036] Figure 3 It is a flow chart of the pipeline corrosion rate detection method in Example Three.

[0037] In the figure: 1-test piece; 11-first test piece; 12-second test piece; 13-first mounting through hole; 14-groove; 2-frame body; 21-fixed beam; 22-connecting column; 23-second mounting through hole; 31-mounting bolt; 32-mounting nut; 4-separation spacer; 5-pipe body. DETAILED DESCRIPTION

[0038] ​To make the objectives, technical solutions, and advantages of this invention clearer, the pipeline corrosion rate detection device and method of this invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention.

[0039] Example 1

[0040] like Figure 1 As shown, a pipe corrosion rate detection device includes a test piece 1 and a frame 2. The test piece 1 is made of the same material as the pipe (not shown). The frame 2 includes a fixing beam 21, and the test piece 1 is detachably connected to the fixing beam 21. The fixing beam 21 and the test piece 1 are arranged in a space communicating with the inner cavity of the pipe, so that the test piece 1 is located in the same fluid environment as the inside of the pipe. That is, when the fluid flows through the inside of the pipe, the fluid will simultaneously corrode both the pipe corrosion rate detection device and the inner wall of the pipe, and the corrosion environments of the two are the same. Since the test piece 1 is made of the same material as the pipe, it can be assumed that the corrosion rate of the test piece 1 and the inner wall of the pipe are the same. Therefore, by only detecting the corrosion rate of the test piece 1, the corrosion rate of the pipe can be predicted, thereby enabling repair or replacement of the pipe before it fails, avoiding disruption to normal operation.

[0041] Specifically, such as Figure 2 As shown, it also includes mounting bolts 31 and mounting nuts 32. The test piece 1 has a first mounting through hole 13, and the fixing beam 21 has a second mounting through hole 23. The mounting bolts 31 pass through the first mounting through hole 13 and the second mounting through hole 23 in sequence and are threaded onto the mounting nuts 32 to connect the test piece 1 to the fixing beam 21. In actual manufacturing, one test piece 1 can be connected to the fixing beam using two mounting bolts 31 and two mounting nuts 32 to improve the stability of the test piece 1 installation and prevent it from falling off the fixing beam 21. This facilitates the installation or removal of the test piece 1 and the fixing beam 21. It should be noted that the detachable connection method between the test piece 1 and the fixing beam 21 is not limited to this; any other method that achieves the purpose of the invention can be used.

[0042] Furthermore, such as Figure 2As shown, the test piece 1 and the fixed beam 21 are separated by a separation spacer 4, so that there is a gap between the test piece 1 and the fixed beam 21 along the axis direction of the mounting bolt 31. In this way, the test piece 1 and the fixed beam 21 are prevented from being attached to each other, so that the contact area of the test piece 1 with the fluid is reduced, and the corrosion of the test piece 1 by the fluid is affected. In actual production, the separation spacer 4 can be made of insulating material (such as polytetrafluoroethylene), and insulating spacers (made of polytetrafluoroethylene) can be arranged between the head of the mounting bolt 31 and the test piece 1 and between the mounting nut 32 and the fixed beam 21 to prevent crevice corrosion and galvanic corrosion.

[0043] In actual production, in order to improve the adaptability of the work, as shown in Figure 1 The number of test pieces 1 is at least two, including at least one first test piece 11 and at least one second test piece 12. The first test piece 11 is in the shape of a rectangular body, and the six end faces of the first test piece 11 are smooth planes. At this time, the corrosion rate of the first test piece 11 is detected to determine the corrosion rate of the pipeline under the condition that the inner wall is intact. As shown in Figure 2 The second test piece 12 is in the shape of a rectangular body, and a cylindrical groove 14 is arranged on one of the end faces. At this time, the corrosion rate of the second test piece 12 is detected to determine the corrosion rate of the pipeline when the inner wall has corrosion pits. Specifically, the number of second test pieces 12 is at least two, and the diameters and / or depths of the grooves 14 on any two second test pieces 12 are different. In this way, the second test pieces 12 with different diameters and / or depths of the grooves 14 can be used to predict the corrosion rates of pipelines with inner walls having different specifications of corrosion defects.

[0044] Example Two

[0045] This embodiment includes all the technical features of Example One, and the difference from Example One is that, as shown in Figure 1 The pipe body 5 can be arranged on the flow passage of the pipeline, so that the fluid flowing through the pipeline can also flow through the pipe body 5. The frame body 2 and the test piece 1 are arranged in the inner cavity of the pipe body 5, and the frame body 2 further includes a connecting column 22, and the fixed beam 21 is fixedly connected to the inner wall of the pipe body 5 through the connecting column 22. In actual production, the two ends of the connecting column 22 can be welded to the inner wall of the fixed beam 21 and the pipe body 5, respectively, and argon arc welding can be used to improve the welding strength. After welding, anticorrosive paint can be applied at the welding position. In use, a pipe segment with the same length as the pipe body 5 can be directly cut from the pipeline by gas cutting, and then the pipe segment 5 with the test piece 1 and the frame body 2 inside is replaced and installed on the pipeline by continuous welding.

[0046] Example Three

[0047] A method for detecting the corrosion rate of a pipeline, using the pipeline corrosion rate detection device described in Embodiment One and / or Embodiment Two, as shown in Figure 3 comprises the steps of:

[0048] S100, weighing the test piece and recording the initial weight G1 of the test piece;

[0049] S200, connecting the test piece to the fixed beam;

[0050] S300, placing the fixed beam with the test piece connected to it in a space communicating with the inner cavity of the pipeline and recording the placement time T of the test piece in the space;

[0051] S400, removing the fixed beam with the test piece connected to it from the space communicating with the inner cavity of the pipeline;

[0052] S500, detaching the test piece from the fixed beam and weighing it to obtain the post-test weight G2 of the test piece, while measuring the depth H of the corrosion pits on the test piece;

[0053] S600, calculating the general corrosion rate V1 and the pitting corrosion rate V2;

[0054] wherein V1 = C x {(G1 - G2) / S x T x p}, C is a conversion coefficient, usually taking a value of 8.67 x 10 4 , S is the surface area of the test piece, and p is the density of the test piece;

[0055] V2 = H / T.

[0056] In actual use, the number of test pieces 1 is at least two, including at least one first test piece and at least one second test piece. The first test piece 11 is in the shape of a rectangular body, and the six end faces of the first test piece 11 are smooth planes, and the second test piece 12 is in the shape of a rectangular body, and a cylindrical groove 14 is provided on one of the end faces.

[0057] When calculating the general corrosion rate V1 and the pitting corrosion rate V2 of the first test piece, G1 is the initial weight of the first test piece, G2 is the post-test weight of the first test piece, S is the surface area of the first test piece, p is the density of the first test piece, and H is the depth of the surface corrosion pits of the first test piece after testing. At this time, the calculated general corrosion rate V1 and pitting corrosion rate V2 can be used to determine the general corrosion rate V1 and pitting corrosion rate V2 of a pipe with no defects on the inner surface.

[0058] When the overall corrosion rate V1 and the pitting corrosion rate V2 of the second test piece are calculated, G1 is the initial weight of the second test piece, G2 is the weight of the second test piece after the test, S is the surface area of the second test piece, p is the density of the second test piece, and H is the depth of the surface corrosion pits of the second test piece after the test. At this time, the overall corrosion rate V1 and the pitting corrosion rate V2 calculated can be used to determine the overall corrosion rate V1 and the pitting corrosion rate V2 of a pipe with an inner surface having the same size as the groove on the second test piece.

[0059] In step S500, after the test piece is detached from the fixed beam, the test piece is first cleaned, and then weighed and the depth of the corrosion pits is measured, so as to ensure the accuracy of the measurement of the weight of the test piece after the test and the depth of the surface corrosion pits.

[0060] Specifically, in the measurement of the corrosion depth H of the test piece, the depths of n corrosion pits on the surface of the test piece are measured respectively to obtain a first corrosion depth H1, a second corrosion depth H2, …, and an n-th corrosion depth Hn, and H=(H1+H2+…+Hn) / n, where n is an integer greater than 1.

[0061] Preferably, the pipeline corrosion rate detection device comprises a pipe body, and the frame body further comprises a connecting column.

[0062] In step S100, the fixed beam connected with the test piece is fixedly connected to the inner wall of the pipe body through the connecting column, and then the pipe body is installed on the flow path of the pipeline. The specific manner in which the fixed beam is fixedly connected to the inner wall of the pipe body through the connecting column, and the specific manner in which the pipe body is installed on the flow path of the pipeline can be referred to in Embodiment One, which will not be described here.

[0063] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A device for detecting pipeline corrosion rate, characterized in that: include: Test piece (1), frame (2), mounting bolts (31), mounting nuts (32) and separator (4); The test piece (1) is made of the same material as the pipe. The frame (2) includes a fixed beam (21). The test piece (1) is detachably connected to the fixed beam (21). The fixed beam (21) and the test piece (1) are arranged in a space communicating with the inner cavity of the pipe, so that the test piece (1) can be located in the same fluid environment as the inside of the pipe. The number of test pieces (1) is at least two, including at least one first test piece (11) and at least one second test piece (12). The first test piece (11) is rectangular in shape, and all six end faces of the first test piece (11) are smooth planes; The second test piece (12) is rectangular in shape and has a cylindrical groove (14) on one of its end faces. The test piece (1) is provided with a first mounting through hole (13), and the fixed beam (21) is provided with a second mounting through hole (23). The mounting bolt (31) passes through the first mounting through hole (13) and the second mounting through hole (23) in sequence and is threaded onto the mounting nut (32) to connect the test piece (1) to the fixed beam (21). The separating gasket (4) is disposed between the test piece (1) and the fixing beam (21) so that there is a gap between the test piece (1) and the fixing beam (21) along the axial direction of the mounting bolt (31).

2. The device for detecting pipeline corrosion rate according to claim 1, characterized in that: The number of the second test piece (12) is at least two, and the diameter and / or depth of the groove (14) on any two of the second test pieces (12) are different from each other.

3. The device for detecting pipeline corrosion rate according to any one of claims 1 to 2, characterized in that: It also includes the tube body (5); The pipe body (5) can be installed in the flow passage of the pipeline so that the fluid flowing through the pipeline can flow through the pipe body (5) at the same time; The frame (2) and the test piece (1) are both located in the inner cavity of the tube (5). The frame (2) also includes a connecting column (22). The fixed beam (21) is fixedly connected to the inner wall of the tube (5) through the connecting column (22).

4. A method for detecting pipeline corrosion rate, using the pipeline corrosion rate detection device as described in any one of claims 1 to 3, characterized in that: Including the following steps: S100. Weigh the test piece and record the initial weight G1 of the test piece. S200. Connect the test piece to the fixed beam; S300. Place the fixed beam connected to the test piece in the space communicating with the inner cavity of the pipe, and record the placement time T of the test piece in the space. S400. Remove the fixed beam with the test piece attached from the space communicating with the inner cavity of the pipe. S500. Remove the test piece from the fixed beam and weigh it to obtain the post-test weight G2 of the test piece, and at the same time measure the depth H of the corrosion pit on the test piece. S600, calculate the overall corrosion rate V1 and the pitting corrosion rate V2; Where V1=C×{(G1-G2) / S×T×ρ}, C is the conversion factor, S is the surface area of ​​the sample, and ρ is the density of the sample; V2 = H / T.

5. The method for detecting pipeline corrosion rate according to claim 4, characterized in that: In step S500, after the test piece is removed from the fixed beam, it is first cleaned, then weighed and the depth of the corrosion pit is measured.

6. The method for detecting pipeline corrosion rate according to claim 5, characterized in that: The measurement of the corrosion depth H on the specimen includes: The depths of the n corrosion pits on the surface of the test piece are measured respectively to obtain the first corrosion depth H1, the second corrosion depth H2, ..., the nth corrosion depth Hn, and H = (H1 + H2 + ... + Hn) / n, where n is an integer greater than 1.

7. The method for detecting pipeline corrosion rate according to any one of claims 4 to 6, characterized in that: The pipeline corrosion rate detection device includes a pipe body, and the frame also includes a connecting column; In step S100, the fixed beam with the test piece attached is fixedly connected to the inner wall of the pipe body via the connecting column, and then the pipe body is installed on the flow path of the pipeline.

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