CN117804890B

CN117804890B - Pipe fitting stress corrosion test device and method

Info

Publication number: CN117804890B
Application number: CN202410224255.XA
Authority: CN
Inventors: 鲍一晨; 孟凡江; 杨义忠; 曹昱澎; 杨晓蕾; 石秀强; 刘晓强; 李荣博
Original assignee: Shanghai Nuclear Engineering Research and Design Institute Co Ltd
Current assignee: Shanghai Nuclear Engineering Research and Design Institute Co Ltd
Priority date: 2024-02-29
Filing date: 2024-02-29
Publication date: 2024-06-04
Anticipated expiration: 2044-02-29
Also published as: CN117804890A

Abstract

The utility model provides a pipe fitting stress corrosion test device, includes rotatory loading mechanism, and rotatory loading mechanism includes pivot and a plurality of loading arm, and loading arm one end is connected in the pivot, and wherein at least part loading arm can rotate in order to provide the loading load around the pivot, is provided with the loading position that is used for installing test pipe fitting between the adjacent loading arm. Through this test device, can carry out stress corrosion test to a plurality of test pipe fittings simultaneously convenient and fast, improve test efficiency, reduce test cost. The invention also provides a pipe stress corrosion test method.

Description

Pipe fitting stress corrosion test device and method

Technical Field

The invention belongs to the field of stress corrosion tests, and particularly relates to a device and a method for testing stress corrosion of a pipe fitting.

Background

Stress corrosion phenomenon widely exists on structural members exposed to the atmosphere, the ocean or other corrosive environments for a long time, and in application scenes such as petrochemical industry, ocean engineering, nuclear power generation and the like, stress corrosion is one of important factors causing part failure, and once key equipment parts are damaged or broken due to stress corrosion, serious safety problems and huge economic losses are easily caused. Thus, stress corrosion sensitivity is a very critical performance parameter in the choice of materials and life prediction evaluation of critical equipment components. At present, conventional stress corrosion performance testing methods comprise a U-shaped bending test, a constant load tensile test, a slow strain rate tensile test and the like, the methods often require that test materials are prepared into a standard sample based on a sheet sample, each sample needs to be loaded independently, and the loading process has high requirements, so that the method is difficult to be applied to the test of batch pipe fittings. The stress corrosion test can be carried out on the pipe fitting by the collapse method, but the conventional collapse method test device is difficult to realize multi-sample loading and is difficult to meet engineering application requirements of batch test. Therefore, the pipe fitting stress corrosion test device capable of conducting batch test has high practical value for improving the stress corrosion test efficiency.

Disclosure of Invention

The invention aims to provide a pipe stress corrosion test device which improves the efficiency of batch stress corrosion tests. The invention also provides a stress corrosion test method.

According to an embodiment of one aspect of the present invention, there is provided a pipe stress corrosion test apparatus, including a rotary loading mechanism, the rotary loading mechanism including a rotating shaft and a plurality of loading arms, one ends of the plurality of loading arms being connected to the rotating shaft, at least a portion of the loading arms being rotatable about the rotating shaft to provide a loading load, a loading position being provided between adjacent loading arms, the loading position being provided with a pipe positioning structure.

The stress corrosion test device for the pipe fitting can perform stress corrosion test on one or more pipe fittings by a compressive collapse method in a rotary loading mode; when synchronous tests are carried out on a plurality of pipe fittings, the same or different loading loads can be further applied, and the test efficiency and the coverage range of test parameters are improved.

Further, in some embodiments, one of the loading positions is disposed between each pair of adjacent loading arms, and different loading positions have different radial distances with respect to the rotation axis. The loading positions are arranged at different radial distances, so that different loading loads can be provided through the same loading torque on one hand, and the structural simplification of the test device is realized; on the other hand, the failure sequence of the test pieces at different loading positions can be identified through different angular displacements of the loading arm.

Further, in some embodiments, the rotary loading mechanism further comprises a base, the rotary loading mechanism is connected to the base, the loading arm comprises a fixed arm and a driving arm, and the fixed arm is fixedly arranged relative to the base; the pipe fitting stress corrosion test device further comprises a driving mechanism, wherein the driving mechanism is connected with the driving arm and can drive the driving arm to swing relative to the fixed arm.

Further, in some embodiments, the loading arm further includes at least one driven arm disposed between the driving arm and the fixed arm along a swing direction of the driving arm, the driven arm being capable of swinging with respect to the driving arm and the fixed arm. The driving arm can sequentially push each driven arm through the loading piece, so that synchronous loading of a plurality of loading positions can be realized only by driving the driving arm.

Further, in some embodiments, the loading arm is provided with a plurality of mounting holes, the mounting holes are used for mounting the pipe positioning structure, and the mounting holes are arranged along the length direction of the loading arm.

Further, in some embodiments, the tubular positioning structure is configured as a loading block protruding from the loading arm, and the rotary loading mechanism applies a load to the tubular to be tested through the loading block. The shape and the mounting position of the loading block are designed, so that the loading block can adapt to pipe fittings to be tested with different specifications, and the load distribution can be flexibly adjusted according to test requirements.

Further, in some embodiments, the apparatus further comprises an angle measurement mechanism that measures the angular displacement of the loading arm during stress corrosion testing. The stress corrosion failure state of the pipe fitting can be effectively judged by measuring the angular displacement of the loading arm.

Further, in some embodiments, the apparatus further comprises an angle measurement mechanism that measures an angular displacement of the active arm relative to the stationary arm. And the angular displacement of the driving arm is measured, and the loading parameter of the failure pipe fitting can be judged according to the magnitude of the angular displacement.

According to an embodiment of another aspect of the present invention, there is provided a pipe stress corrosion test method using the pipe stress corrosion test apparatus provided in any one of the preceding embodiments.

Further, in some embodiments, the method includes the steps of: providing a plurality of test tubes, wherein the outer diameters of the test tubes are the same; installing the plurality of test tubes at a plurality of loading positions so that the plurality of test tubes have different radial distances relative to the rotating shaft; applying a loading load to the plurality of test tubes by the loading arm; providing a corrosion test environment, and measuring the angular displacement of the loading arm in the test process to obtain stress corrosion failure data of the plurality of test pipes.

Drawings

FIG. 1 is a schematic diagram of a stress corrosion test apparatus for pipe fittings according to an embodiment;

FIG. 2 is a top view of a pipe stress corrosion test apparatus according to one embodiment;

FIG. 3 is a schematic diagram of an embodiment of an actuator arm structure;

FIG. 4 is a schematic view of a driven arm according to an embodiment;

FIG. 5 is a schematic view of a loading pin according to an embodiment.

The above drawings are provided for the purpose of explaining the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, and are not intended to limit the present invention. For simplicity of illustration, the above figures show only schematically the structures related to the technical features of the present invention, and not all the details and the complete structures are exactly drawn according to the figures.

Detailed Description

The invention will now be described in further detail with reference to the accompanying drawings by means of specific examples.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment herein. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments limited to the same embodiment. Those skilled in the art will appreciate that embodiments herein may be combined with other embodiments without structural conflict.

In the description herein, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and the like are to be construed broadly and may be movably connected, fixedly connected, or integrally formed. The specific meaning of the above terms in the embodiments of the present application will be understood by those skilled in the art according to specific circumstances.

In the description herein, terms such as "upper," "lower," "left," "right," "transverse," "longitudinal," "height," "length," "width," and the like that indicate an azimuth or positional relationship are intended to accurately describe the embodiments and simplify the description, and do not limit the details or structures involved to having to have a particular azimuth, mount or operate in a particular azimuth, and are not to be construed as limiting embodiments herein.

In the description herein, the terms "first," "second," and the like are used merely to distinguish between different objects and should not be construed as indicating relative importance or defining the number, particular order, or primary and secondary relationships of the technical features described. In the description herein, the meaning of "plurality" is at least two.

For key parts in the fields of petrochemical industry, ocean engineering, nuclear power and the like, a large number of stress corrosion tests are required to be carried out to determine the performance parameters of the parts, so that the material selection and the structural optimization of the parts are guided, the expected service life of the parts is accurately estimated, and safety accidents and economic losses caused by unexpected failure of important parts are avoided. The existing stress corrosion test method is generally only capable of loading the individual parts, and is large in repeated workload and long in test period when a large number of tests are carried out, and meanwhile, multi-parameter parallel tests such as gradient stress tests are difficult to develop.

In order to solve the above problems, an embodiment of an aspect of the present invention provides a pipe stress corrosion test apparatus. The device is shown in fig. 1, and comprises a disc-shaped base 1, wherein a rotating shaft 2 is arranged in the center of the base 1, and a plurality of radially arranged loading arms are connected to the rotating shaft 2. The loading arm includes a fixed arm 33 fixedly disposed relative to the base 1 and a driving arm 31 capable of swinging relative to the fixed arm 33, four driven arms 32 are disposed between the driving arm 31 and the fixed arm 33 along the swinging direction of the driving arm 31, and the driven arms 32 can swing freely around the rotating shaft 2. Load positions are provided between the adjacent driving arm 31 and driven arm 32, between the driven arm 32 and driven arm 32, and between the driven arm 32 and fixed arm 33 for mounting the test tube 5 and applying a load to the test tube 5 by relative swinging between the load arms. With reference to fig. 2, a loading position is provided between each pair of adjacent loading arms for mounting a test tube 5, wherein different test tubes 5 have different radial distances with respect to the spindle 2.

As shown in fig. 3, the structure of the driving arm 31 is that one end of the driving arm 31 is a fixed ring 312, the fixed ring 312 is fixedly connected with the rotating shaft 2, and when the rotating shaft 2 rotates, the driving arm 31 can be driven to synchronously rotate together. A plurality of pin holes 311 are provided along the length direction of the driving arm 31 for mounting the loading pins 4 as the pipe positioning structure.

The structure of the driven arm 32 is as shown in fig. 4, one end of the driven arm is a sliding ring 322, and the sliding ring 322 is sleeved on the rotating shaft 2 and is in sliding fit with the rotating shaft 2 so as to allow the driven arm 32 to freely swing around the rotating shaft 2. A plurality of pin holes 321 are provided along the length direction of the driven arm for mounting the loading pins 4 as the pipe positioning structure. Referring to fig. 1, the height difference exists between the fixed ring 312 of the driving arm 31 and the sliding ring 322 of each driven arm 32 relative to the surface of the base 1, so that the connection portions of the driving arm 31 and each driven arm 32 with the rotating shaft 2 are staggered in the axial direction of the rotating shaft 2, and interference in the rotating process is avoided.

Referring to fig. 1 and 2, the fixing arm 33 is fixedly disposed relative to the base 1, and in different embodiments, the fixing arm 33 may be configured as a rod fixedly connected to the base 1, or may be configured as a rib integral with the base 1 or a structure capable of playing a role in limiting the rotation of the driving arm 31 and the driven arm 32 around the rotating shaft 2 in a circumferential direction. The fixing arm 33 is also provided with a pin hole for mounting the loading pin 4.

As shown in fig. 5, the loading pin 4 has a T-shape overall, and has a pin joint portion 42 for connecting with a loading arm and a loading portion 41 for loading the test tube 5. In combination with fig. 2, when test loading is performed, the pin joint parts 42 of the loading pins 4 are inserted into the pin holes of the loading arms to form fixation, and each four loading pins 4 on two adjacent loading arms form a loading position, and the size of the loading position can be adjusted to adapt to test pipes 5 with different outer diameters by inserting the loading pins 4 into the pin holes at different positions, and the radial distance of the rotating shaft 2 of the loading position can also be adjusted to realize different loading load outputs to the test pipes 5 under the same input torque. In different embodiments, the loading portion 41 may be provided as a cylinder, may be provided as a cylinder having an arc-shaped abutment surface matching the profile of the test tube 5, and may be designed into other shapes capable of applying a complex load to the test tube 5 according to the loading requirement.

In a preferred embodiment, the pipe stress corrosion test apparatus is further provided with an angular measurement mechanism, such as an angular displacement sensor, on the drive arm 31 for measuring the angular displacement of the drive arm 31 during the test. When the test tube 5 fails in the test process, the driving arm 31 rotates relative to the fixed arm 33, so that the angular displacement is reflected, and the failure condition of the test tube 5 can be obtained by measuring the angular change of the driving arm 31. In some embodiments, an angle measuring mechanism may be provided on each loading arm to measure the angular change of each loading arm.

In some embodiments, the loading positions between the loading arms may also be set to have the same radial distance with respect to the rotation axis 2, so as to achieve parallel testing under the same stress condition of a plurality of samples.

In some embodiments, the fixed arm 33 may be replaced with another actuator arm that is rotatable in the opposite direction to the actuator arm 31. In other embodiments, a plurality of fixed arms 33 may be provided, where each fixed arm 33 is correspondingly provided with a driving arm 31, and each driving arm 31 can rotate independently, and each driving arm 31 applies a different load.

In some embodiments, the load pins 4 may be replaced with other forms of load blocks, such as load rings that match the peripheral contours of the test tube 5, thereby providing a more uniform load distribution to reduce stress concentrations at the locations where the test tube 5 contacts the load pins 4. In some embodiments, loading pins 4 with different structures or loading blocks of different forms may be provided at different loading positions to apply different stress distribution conditions to the test tube 5.

In some embodiments, the pipe stress corrosion testing device may not be provided with an angle measuring mechanism integrated on the testing device, but an external independent sensor is used for measuring the swing angle of the loading arm, for example, in some embodiments, an external laser displacement sensor or other non-contact angle measuring device may be used for measuring the swing angle of the loading arm in the testing process.

In the preferred embodiment, the actuator arm 31 is driven by a drive motor and provides torque; in other embodiments, hydraulic or pneumatic mechanisms may be used as the driving mechanism, or tension torque conversion may be used to provide torque.

In a preferred embodiment, the pipe stress corrosion test device can be integrated with a test box for providing a corrosion environment, the part above the base is arranged inside the environment test box, and the structures such as the driving device below the base are arranged outside the environment test box so as to avoid corrosion of the driving device. In a preferred embodiment, the base, loading arm and shaft of the pipe stress corrosion test apparatus are fabricated from corrosion resistant materials, including, but not limited to, stainless steel, nickel-based alloys, titanium alloys, ceramic matrix composites, corrosion resistant engineering plastics, and the like.

The pipe fitting stress corrosion test device provided in the embodiment can implement pipe fitting stress corrosion tests under different loading conditions in batches by using a single device, so that the test efficiency is improved, and the test cost is reduced.

In a preferred embodiment, the method of performing stress corrosion testing using a pipe stress corrosion testing apparatus constructed as shown in FIGS. 1-5 is as follows:

First, a plurality of test tubes 5 having the same outer diameter were prepared.

The mounting distance of the loading pins 4 is determined according to the outer diameter of the test tube 5, so that the loading arm only applies load to the test tube 5 through four loading pins forming loading positions when loading the test tube 5, and the loading arm is not in direct contact with the test tube 5.

The stress distribution states of the test pipe fittings 5 with different radial distances relative to the rotating shaft 2 shown in fig. 2 are determined through finite element simulation analysis or calibration test, so that the torque input by the test device and the maximum tensile stress actually born by each test pipe fitting 5 are determined. As can be seen from the loading mode, the area of the test tube 5 subjected to the greatest tensile stress is usually the nearest and farthest positions in the radial direction relative to the rotating shaft 2.

Next, the pipe stress corrosion test device is integrally sealed in an environment test box to provide a corresponding corrosion environment, such as salt spray corrosion, corrosive atmosphere or corrosive liquid environment, torque is applied to the driving arm 31 through the driving device, the driving arm 31 rotates around the rotating shaft 2 to form a pressure load on the test pipe 5, and the pressure load is further transmitted to the next driven arm 32 through each test pipe 5, so that the test pipe 5 at each loading position between the driving arm 31 and the fixed arm 33 is subjected to the pressure load; the radial distance between each test tube 5 and the rotating shaft 2 is different, so that the load born by each test tube 5 is different, and a parallel test group with wider parameter coverage range is formed.

Finally, the swing angle of the active arm 31 is measured by a separate angle measuring mechanism integrated in the active arm 31 or built in the environmental test chamber. When the test tube 5 collapses and fails, the driving arm 31 swings towards the direction of the fixed arm 33, and the swing angles caused by the failure of the test tube 5 at different loading positions are different due to different radial distances between the test tube 5 and the rotating shaft 2, so that the failure sequence of each test tube in the closed environment test box can be determined only through the angular displacement information. In some embodiments, an angle measurement mechanism may also be provided on each of the driving arm and the driven arm to directly measure the angular displacement caused by failure of each test tube 5.

In some embodiments, the stress distribution state of the test pipe fitting can be changed by arranging loading pins 4 or other clamps with different structures at different loading positions, so that the stress corrosion performance test of the pipe fitting under more complex stress conditions is realized.

By the pipe stress corrosion test method provided by the embodiment, systematic tests covering various different loading conditions can be rapidly carried out to test the stress corrosion performance of the pipe, and the method has high practical value in the scenes of pipe material selection or structure optimization and the like in a corrosion environment by a DOE method.

The above-described embodiments are intended to explain the present invention in further detail with reference to the figures so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present disclosure, the structural and method steps of the parts involved are optimized or replaced equivalently, and the implementation manners of the different embodiments are combined on the premise that no conflict between the structural and the principle occurs, which falls within the protection scope of the present disclosure.

Claims

1. The pipe fitting stress corrosion test device is characterized by comprising a rotary loading mechanism, wherein the rotary loading mechanism comprises a rotating shaft and a plurality of loading arms, one ends of the loading arms are connected to the rotating shaft, and at least part of the loading arms can rotate around the rotating shaft so as to apply load through relative swing among the loading arms; a loading position is arranged between the adjacent loading arms, a pipe fitting positioning structure is arranged at the loading position, the pipe fitting positioning structure is configured to protrude out of a loading block arranged on the loading arms, and the rotary loading mechanism applies load to the pipe fitting to be tested through the loading block.

2. A pipe stress corrosion testing device according to claim 1, wherein one said load position is provided between each pair of adjacent said load arms, different said load positions having different radial distances relative to said axis of rotation.

3. The pipe stress corrosion testing device according to claim 1 or 2, further comprising a base, wherein the rotary loading mechanism is connected to the base, the loading arm comprises a fixed arm and a driving arm, and the fixed arm is fixedly arranged relative to the base; the pipe fitting stress corrosion test device further comprises a driving mechanism, wherein the driving mechanism is connected with the driving arm and can drive the driving arm to swing relative to the fixed arm.

4. A pipe stress corrosion testing device according to claim 3 wherein said loading arm further comprises at least one driven arm disposed between said driving arm and said fixed arm in a direction of oscillation of said driving arm, said driven arm being capable of oscillating relative to said driving arm and said fixed arm.

5. The pipe stress corrosion test device according to claim 1 or 2, wherein the loading arm is provided with a plurality of mounting holes, the mounting holes are used for mounting the pipe positioning structure, and the mounting holes are arranged along the length direction of the loading arm.

6. A pipe stress corrosion testing device according to claim 1 or 2, further comprising an angle measuring mechanism, said angle measuring mechanism measuring the angular displacement of said loading arm during a stress corrosion test.

7. A pipe stress corrosion testing device according to claim 3 further comprising an angle measuring mechanism, said angle measuring mechanism measuring the angular displacement of said active arm relative to said fixed arm.

8. A method for testing stress corrosion of a pipe, characterized in that the apparatus for testing stress corrosion of a pipe according to any one of claims 1 to 7 is used.

9. The method of claim 8, comprising the steps of:

Providing a plurality of test tubes, wherein the outer diameters of the test tubes are the same;

installing the plurality of test tubes at a plurality of loading positions so that the plurality of test tubes have different radial distances relative to the rotating shaft;

Applying a loading load to the plurality of test tubes by the loading arm;

Providing a corrosion test environment, and measuring the angular displacement of the loading arm in the test process to obtain stress corrosion failure data of the plurality of test pipes.