Pressing and flattening method for strip-shaped transverse tensile sample of steel pipe

A transverse stretching and flattening technology, applied in the preparation of test samples, etc., can solve problems such as yield strength reduction

Active Publication Date: 2022-06-21
SPECIAL EQUIP SAFETY SUPERVISION INSPECTION INST OF JIANGSU PROVINCE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The present invention provides a method for flattening and flattening steel pipe lath-shaped transverse tensile specimens, which solves the problem of the existing steel pipe lath-shaped transverse tensile specimens. The flattening method leads to the problem that the yield strength is reduced. The present invention reasonably controls the Banschinger effect through a unified and standardized flattening method, so that the test results of the transverse yield strength of the steel pipe sample are stable, reliable and comparable, avoiding misjudgment of product quality and ensuring Safe and reliable pipeline operation is of great significance

Method used

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  • Pressing and flattening method for strip-shaped transverse tensile sample of steel pipe
  • Pressing and flattening method for strip-shaped transverse tensile sample of steel pipe
  • Pressing and flattening method for strip-shaped transverse tensile sample of steel pipe

Examples

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Effect test

Embodiment 1

[0020] The transverse yield strength test of Φ508×22mm X70 straight welded steel pipe is carried out as follows.

[0021] 1) According to the requirements of relevant standards, cut the raw material of the strip-shaped transverse tensile sample 3 at the position of 90° from the welding seam between the steel pipe, the arc length is about 440mm, and the width is 100mm, such as figure 1 shown. Because it is flame cutting, the effect of edge heat input on the final specimen is considered.

[0022] 2) Put one end of the strip-shaped sample 3 about 195mm long between the upper pressing plate 1 and the first lower supporting plate 2, such as figure 2 shown. Put t=22, σ=552MPa, E=210000MPa into the public announcement:

[0023] R1==t(E / σ-1) / 2==22×(210000 / 552-1) / 2≈4174≈4200;

[0024] R1 is 4200mm, and the chamfering radius of the two corners of the first lower support plate 2 in contact with the strip-shaped sample 3 is 13mm, and the width is 230mm. Press the upper platen 1 to t...

Embodiment 2

[0030] The transverse yield strength test of the Φ609×18mmX65 straight welded steel pipe of the shale gas well is carried out as follows.

[0031] 1) According to the requirements of relevant standards, cut the raw material of the strip-shaped transverse tensile sample 3 at the position of 90° from the welding seam between the steel pipe, the arc length is about 422mm, and the width is 100mm, such as figure 1 shown. Because it is flame cutting, the effect of edge heat input on the final specimen is considered.

[0032] 2) Put one end of the strip-shaped sample 3 about 185mm long between the upper pressing plate 1 and the first lower supporting plate 2, such as figure 2 shown.

[0033] Put t=18, σ=483MPa, E=210000MPa into the public announcement:

[0034] R1=t(F / σ-1) / 2=18×(210000 / 483-1) / 2≈3907≈3900;

[0035] R1 is 3900mm, the chamfering radius of the two corners of the first lower support plate 2 in contact with the strip-shaped sample 3 is 13mm, and the width is 220mm. P...

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Abstract

The invention provides a flattening and flattening method for a strip-shaped transverse tensile sample of a steel pipe, and solves the problem that the yield strength of the strip-shaped transverse tensile sample of the steel pipe is reduced due to an existing flattening method for the strip-shaped transverse tensile sample of the steel pipe. The method comprises the following steps: cutting a lath-shaped transverse tensile sample with the arc length of about 2a + 4t on a steel pipe, 2a being greater than or equal to 350mm, and t being the thickness of the sample; the upper pressing plate and the first lower supporting plate are both provided with matched arc-shaped parts, the radius R1 of each arc-shaped part is equal to t (E / sigma-1) / 2, sigma is the rated lowest tensile strength of the material, and E is the elastic modulus; two ends of the sample are respectively placed between an upper pressing plate and a first lower supporting plate, and the upper pressing plate is pressed to the lowest position and then released; the second lower supporting plate is provided with an arc-shaped part which is matched with the upper pressing plate and has the radius of R1, and the middle section of the sample is placed between the upper pressing plate and the second lower supporting plate for the length of about 50 + (3-5) t, and the upper pressing plate is released after being pressed to the lowest position; and obtaining a final sample with the length of 350 mm in the middle at two ends of the sample.

Description

Technical field [0001] The invention relates to the technical field of flattening and flattening methods for curved specimens. Background technique [0002] Oil and gas transmission pipelines are energy arteries. Preventing plastic deformation of pipeline steel pipes during operation is a basic criterion for pipeline design. The main stress of the pipeline is the circumferential direction, and the circumferential yield strength is the most important indicator of pipeline design. The hoop yield strength of steel pipes can be tested by rod, plate, expansion ring and hydrostatic pressure specimens. Rod-shaped, expanded-ring and hydrostatic specimens are limited in use due to minimum sample diameter requirements, high processing costs and high testing costs; plate specimens are the basic choice for testing. [0003] During the processing of plate specimens, the curved steel plate needs to be flattened first. Different flattening methods lead to different Banschinger effects. ...

Claims

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Application Information

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IPC IPC(8): G01N1/28B21D1/00
CPCG01N1/28B21D1/00
Inventor 董文利宋高峰浦江陈宏达申兆熙朱庆南燕集中朱婷俞瞳
Owner SPECIAL EQUIP SAFETY SUPERVISION INSPECTION INST OF JIANGSU PROVINCE
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