Full-scale test method for pressure bearing capacity and ductile-brittle transition behavior of cryogenic gas transmission steel pipes

Abstract

The invention discloses a full-scale test method for the pressure bearing capacity and ductile-brittle transition behavior of a low-temperature gas transmission steel pipe. Defects are prefabricated on the surface of the test steel pipe, and plugs are welded at both ends of the steel pipe to investigate the pressure bearing capacity of the steel pipe with defects under low temperature conditions. ; Place the steel pipe in the pipe trench, and use reinforced concrete to anchor the plugs at both ends of the steel pipe to build the test pipeline; install strain gauges, clip-type extensometers, surface temperature sensors and other measuring devices on the steel pipe; The pipe body of the steel pipe is filled with liquid nitrogen and alcohol coolant to realize the low temperature control of the whole test steel pipe; after the test steel pipe is filled with cryogenic liquid, the burst pressure is reached by injecting nitrogen, and the pressure inside the pipe, the wall temperature of the pipe body, The strain of the pipe body, the opening of the crack mouth at the prefabricated crack and the image data information are used to analyze and determine the fracture resistance curve and the ductile-brittle transition temperature of the steel pipe. The invention is economical, simple and easy to operate, can precisely control temperature and is safer.

Description

technical field [0001] The invention belongs to the technical field of structural integrity testing of gas transmission pipelines, and in particular relates to a full-scale test method for determining the pressure bearing capacity and ductile-brittle transition behavior of low-temperature gas transmission steel pipes. Background technique [0002] With the rapid development of polar energy in the world, a large number of natural gas pipelines and their ancillary facilities need to pass through extremely cold regions, where the lowest temperature even reaches -60°C. When the pipeline, especially the pipeline with defects, is in low temperature environment, it is easy to break suddenly when the stress level is not high, or even lower than the yield limit of the material. Especially for X80 steel grade (yield strength ≥ 555MPa), its yield strength exceeds the current steel grade level of low-temperature pressure vessel steel (490MPa), the sensitivity to low-temperature brittle ...

AI Technical Summary

Problems solved by technology

When studying the pressure-bearing capacity and ductile-brittle transition behavior of pipelines by means of small samples such as tension, impact, and drop weight, the impact of size constraints on fracture toughness cannot be considered, so it is impossible to quantitatively analyze whether brittle fractures occur in components and accurate judgment, it is also impossible to determine the bearing capacity of pipelines, especially pipelines with defects, at low temperatures

[0003] Once the high-pressure oil and gas pipeline fails and explodes, it will cause huge disasters and losses

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