Selection method of test sample for steel pipe transverse yield strength test
A technology of yield strength and steel pipe, which is applied in the field of steel pipe transverse yield strength test sample selection, can solve problems such as danger and insufficient steel pipe strength, and achieve the effect of ensuring safety
Inactive Publication Date: 2010-07-21
BEIJING LONGSHINE OIL TUBULAR TECH
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Problems solved by technology
That is to say, due to the existence of residual stress, even if the test results of both the plate sample and the round bar sample are qualified, the actual strength of the steel pipe may be insufficient and dangerous.
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[0015] The design of pipeline strength is the key to ensure the safe operation of oil pipelines. The design formula of pipeline strength is given in "GB50251-2003 Code for Design of Gas Pipeline Engineering", as follows:
[0016]
[0017] In the formula, the calculated wall thickness of δ-steel pipe (cm)
[0018] P-design pressure (MPa)
[0019] D-Steel pipe outer diameter (cm)
[0020] σrs-the minimum yield strength of the steel pipe in the transverse direction (MPa)
[0021] F-strength design factor (mainly considering wall thickness tolerance)
[0022] - weld coefficient;
[0023] t-temperature reduction factor. When the temperature is less than 120°C, the value of t is 1.0.
[0024] In order to obtain the real minimum yield strength σrs in the transverse direction of the steel pipe, material failure or destructive tests are required, but in engineering practice, most components are in a complex stress state, and it is impractical to conduct material failure or de...
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Abstract
The invention discloses a selection method of a test sample for a steel pipe transverse yield strength test, which overcomes the problem of that puzzlement is caused to the inspection and the judgment in practical engineering due to different test results by selecting different test samples existing in the pipeline design process at present, and meanwhile, the influence of residual stress on steel pipe strength, i.e. bearing capacity is taken into comprehensive consideration in the sample selecting process so as to ensure that the selection of a steel pipe yield strength test sample is more reasonable and economical. The invention adopts the technical scheme that a test sample is determined and selected through the ratio relation among the hydrostatic pressure circumferential yield strength sigmahs of a steel pipe to be tested, the tested yield strength sigmabs of a round bar sample and the tested yield strength sigmass of a platy sample; when the sigmahs is not less than 1.16sigmabs, the test result of the round bar sample is adopted as a standard for judging whether a product is qualified; when the sigmahs is not less than 1.16sigmass and less than 1.16sigmabs, the test result of the platy sample is adopted as the standard for judging whether the product is qualified; and when the sigmahs is not more than 1.16sigmass, the sample is indicated to have overlarge residual stress and needs to be with the reduced residual stress or degraded for use.
Description
technical field [0001] The invention relates to a method for selecting samples for yield strength testing, in particular to a method for selecting samples for testing transverse yield strength of steel pipes. Background technique [0002] Pipeline is the most economical and safest way to transport oil and natural gas. In order to ensure the transmission efficiency, increasing the transmission pressure is the only way. Therefore, having a certain pressure bearing capacity is the most basic condition for pipeline steel pipes to meet the use requirements. Preventing plastic deformation of pipelines during operation is a prerequisite for ensuring pipeline safety. The yield strength of the steel pipe body, especially the transverse yield strength of the steel pipe in the principal stress direction, directly reflects the pressure bearing capacity of the steel pipe, is the basic basis for the strength design of the pipeline, and is the most important parameter to ensure the safe op...
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IPC IPC(8): G01N3/12
Inventor 陈宏达冯耀荣申昭熙董保胜李云龙
Owner BEIJING LONGSHINE OIL TUBULAR TECH