Test evaluation method for preventing three-way low-stress brittle fracture

Abstract

The invention, which belongs to the technical field of three-way test evaluation for an oil-gas transmission pipeline, particular relates to a test evaluation method for preventing three-way low-stress brittle fracture. The method comprises: step one, carrying out preliminary checking on a three-way test sample; step two, manufacturing a defect in a strength weak region of the three-way test sample; step three, carrying out hydrostatic testing on the three-way test sample with a defect; and step four, carrying out low-stress brittle fracture determination based on a hydrostatic testing result.According to the invention, on the basis of the manufacturing process and structural characteristics of the three-way unit, the test evaluation for preventing the low-stress brittle fracture is carried out by using a hydrostatic explosion testing method with the defected three-way unit by using the anti-brittle-fracture design concept and the engineering experience of the pressure container as reference, so that the extreme pressure-bearing capability analysis is utilized and the complete evaluation of the three-way unit having the defect is considered. Therefore, the guidance and basis are provided for design selection of a three-way pipe in a pipeline project and safe usage of the defect-contained three-way unit.

Description

technical field [0001] The invention belongs to the technical field of tee test evaluation for oil and gas transmission pipelines, and in particular relates to a test evaluation method for preventing tee low stress brittle fracture. Background technique [0002] Pressure vessels are key equipment closely related to many industries of the national economy, especially in petrochemical, power energy, national defense weapons, nuclear power installations and other fields, where they play a pivotal role. Since the 1940s, many welded structures such as pressure vessels, pipelines, chemical equipment and large structures have experienced low-stress brittle fracture many times, causing huge losses. Low stress brittle fracture refers to the brittle failure of materials or structural parts under the action of low stress. Its main characteristics are: the nominal stress of the structural part is lower than the yield strength of the material at the time of fracture, and there is no or o...

AI Technical Summary

Problems solved by technology

However, there are obvious deficiencies in the low-temperature brittle fracture control of the tee by this method, mainly because the composition design and manufacturing process of the tee are different from the pipeline steel pipe, and its structure is more complicated, and the thickness often reaches more than 50mm, which improves the test performance. In addition, the size of the sample that meets the fracture mechanics test may not be prepared, and the K of the material cannot be tested. IC measurement; and to determine the K of the material IC It is a very complicated and costly matter, the test cycle is relatively long, and the test process is relatively cumbersome

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