Full-scale testing method for pressure bearing capacity and ductile-brittle transition behaviors of gas transmission steel pipe at low temperature

Abstract

The invention discloses a full-scale testing method for pressure bearing capacity and ductile-brittle transition behaviors of a gas transmission steel pipe at low temperature. The method comprises thefollowing steps: a defect is preformed in the surface of a test steel pipe, plugs are welded at two ends of the steel pipe, and the pressure bearing capacity of the defective steel pipe at low temperature is tested; the steel pipe is placed in a pipe trench, and the plugs at two ends of the steel pipe are anchored by reinforced concrete for constructing a test pipeline; measuring devices such asa strain gauge, a clip gauge and a surface temperature sensor are mounted on the steel pipe; low temperature control of the whole test steel pipe is realized by filling the body of the test steel pipewith liquid nitrogen and an alcohol cooling liquid; after the test steel pipe is filled with the low-temperature liquid, bursting pressure is reached by injecting nitrogen, and a fracture resistancecurve and ductile-brittle transition temperature of the steel pipe are analyzed and determined by acquiring information of pipe internal pressure, pipe body wall temperature, pipe body strain, openingamount of crack mouth at a preformed crack and video data. The method is economical, simple, easy to operate and safer, and can realize precise temperature control.

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

Images