A sulfide stress corrosion cracking test device

Abstract

The invention relates to an axial tensile loading testing apparatus and particularly relates to a sulfide stress corrosion cracking testing apparatus. The testing apparatus at least comprise a container, sample chucks and a support frame, wherein a sample to be tested is arranged in the container; the sample chucks are arranged on both ends of the container and the support frame is used for fixing the sample chucks; the sample chucks and the sample to be tested are co-axially arranged and the sample chucks can reciprocate on the support frame along the axial direction. The apparatus is characterized in that each sample chuck includes a chuck part and a loading part; the chuck part is used for directly fixing both ends of the sample to be tested, the loading part is co-axially arranged together with the chuck part and is matched with the support frame; the articulated shaft axis of the chuck parts and the loading parts is perpendicular to the axis of the sample chuck. According to the apparatus, loads exerted in a testing process can be precisely detected, and thus bending moments forming on the sample can be eliminated in a loading process, the accuracy of the testing results can be effectively ensured, and the operation is reliable, steady and efficient.

Description

technical field [0001] The invention relates to an axial tensile loading test device, in particular to a sulfide stress corrosion cracking test device for carrying out axial tensile loading and metering on a sample in a sulfide stress corrosion test. Background technique [0002] With the sustained and rapid development of my country's economy, our demand for energy is also increasing. At present, clean energy such as nuclear energy and wind energy cannot replace fossil energy such as oil and natural gas, and H 2 S is one of the most corrosive and harmful media in oil and gas. With the development of sulfur-containing oil and gas fields and the increasing processing volume of imported high-sulfur crude oil, the corrosion damage of hydrogen sulfide medium has penetrated into the oil and gas drilling, transportation and processing industries. More and more carbon steel and low alloy steel equipment , Pressure vessels and pipelines undergo corrosion, sulfide stress corrosion c...

AI Technical Summary

Problems solved by technology

The constant load device uses weights to control the load. The device is huge, takes up a lot of space, and requires a lot of weights. It is inconvenient to carry and the actual control accuracy is poor. Accuracy of test results

The stress ring device is widely used at present, and its structure is described in the Chinese patent text with the patent name CN101988879 A entitled "Loading method and monitoring system for sulfide stress corrosion uniaxial tensile test". The load is applied through the deformation of the stress ring. Each stress ring has a unique fitting curve and relationship formula between the stress load and the deformation. According to the stress level that the material needs to be applied, the deformation of the stress ring is calculated, and then the external force is applied to make the stress The deformation of the ring is measured by measuring the amount of deformation to measure the magnitude of the applied stress load. It often has the following problems: First, in the process of measuring the amount of deformation mentioned above, there are errors in actual operation regardless of whether the dial indicator or the vernier caliper is used. When using the dial indicator In theory, this kind of measurement is inaccurate. Since the bottom of the stress ring is not fixed, it will deform under the action of stress. However, this part of the deformation cannot be measured when using a dial indicator. When using a vernier caliper to measure When the stress ring is deformed, this measurement can be very accurate in theory, but the measurement error is relatively large in actual operation. The vernier caliper measures the distance between two points. When the two points to be measured are not on the same vertical plane, it will be Errors are generated, and theoretical calculations show that when the two points to be measured are offset by 3 degrees in the vertical direction, the resulting measurement errors are:

[0007] When the loading stress of the stress ring reaches 500MPa, the displacement of the stress ring is between 1.5 and 2mm (related to the range of the stress ring), and the measurement error for this kind of equipment that requires precise loading reaches 15% to 20%. It has far exceeded the range of 0-5% measurement error in the test process, which is considered inaccurate in the test process; secondly, in the current structure, all parts of the stress ring are connected by threads, and there are no other active links. When the load is applied, if the sample is out of axis with the loaded fixture, an additional bending moment will be generated on the sample. The more obvious the out-of-axis phenomenon, the greater the bending moment, which is often a hidden danger that affects the accuracy of test results. Neglected by the testers; finally, as the stress ring at the core of the device, the actual source is dependent on imports, and the high cost of use and maintenance also brings great obstacles to the actual popularization and use of the device.

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