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Detecting method for flexural fatigue crack initiation process of submarine pipeline

A technology for fatigue cracks and submarine pipelines, applied in the direction of applying stable shear force to test the strength of materials, measuring devices, instruments, etc., can solve the problems of prone to accidents and high probability of failure of pressure pipelines

Active Publication Date: 2017-09-19
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Submarine pipelines are a type of pressure pipelines, but the difference from ordinary pressure pipelines is that submarine pipelines have to withstand the impact of tides, waves, currents, sea ice, and ocean falling objects. Impact, as well as seawater erosion, friction of fishing nets, etc., these loads make submarine pipelines more common pressure pipelines have a higher probability of failure and are more prone to accidents

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  • Detecting method for flexural fatigue crack initiation process of submarine pipeline
  • Detecting method for flexural fatigue crack initiation process of submarine pipeline
  • Detecting method for flexural fatigue crack initiation process of submarine pipeline

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Embodiment 1

[0049] Embodiment 1 detection method

[0050] The embodiment of the present invention provides a detection method for the initiation process of the bending fatigue crack of the submarine pipeline. The detection method is as follows:

[0051] A part of the oil pipeline is taken as the pipeline test piece, and the middle position of the lower end surface of the pipeline test piece is provided with several rows of axisymmetric strain gauges along the axial direction, and the strain gauges in each row are arranged in a row along the radial direction (see figure 1 ), each of the strain gauges is arranged along the axial direction of the pipeline test piece, and is used to detect the axial tensile strain of the pipeline test piece under the action of bending moment; figure 1 Among them, A is the crack, B is the bottom of the pipe test piece, and C is the strain gauge.

[0052] Place the pipe test piece with strain gauges on the platform of the fatigue pressure mechanism, the two en...

Embodiment 2

[0067] Embodiment 2 detection device

[0068] see Figure 6 , the embodiment of the present invention provides a detection device for the initiation process of a subsea pipeline bending fatigue crack that can implement the detection method in Embodiment 1, including a base 31, two support frames 32 symmetrically arranged on the base 31, and two The fatigue pressure mechanism 38 on the platform 31; the pipe test piece 36 is arranged on the support frame 32, and the two ends of the pipe test piece 36 are fixedly connected with a supporting end plate 35, and the middle part of the pipe test piece 36 is symmetrically arranged with two vertical loading plates. plate 41, the pipeline test piece 41 passes through the middle part of the vertical loading plate 41, and a horizontal plate 40 is arranged on the upper end surface of the two vertical loading plates 41; the lower end surface of the support end plate 35 is placed on the upper end surface of the support frame 32; The lower en...

Embodiment 3

[0075] Embodiment 3 Positioning device for welding

[0076] In order to obtain accurate detection results, the embodiment of the present invention provides a positioning device for welding pipe test pieces, see Figure 7-Figure 10 , the positioning device includes a platform 1 and a mobile vehicle 28 that is movable on the platform 1, an intermediate plate 25 is arranged on the platform 1, and two arc-shaped support frames 16 are symmetrically arranged on the mobile vehicle 28, which are located on the outside of the arc-shaped support frame 16. Two fixed splints 8 with arc-shaped notches are symmetrically arranged on the platform 1, and two movable splints 9 with arc-shaped notches are symmetrically arranged on the outer platform 1 of the fixed splint 8, and are symmetrically located on the outer platform 1 of the movable splint 9 There are two movable positioning plates 4; the arc-shaped support frame 16, the fixed splint 8, the movable splint 9 and the movable positioning p...

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Abstract

The invention discloses a detecting method and device for a flexural fatigue crack initiation process of a submarine pipeline. The detecting method comprises: arranging a strain gage in the middle of a pipeline test piece; placing the pipeline test piece on a fatigue pressure application mechanism platform; taking two ends of the pipeline test piece as supporting points and enabling the middle of the pipeline test piece to be suspended; applying a downward cyclic load to two positions symmetric along the middle of the pipeline test piece by a fatigue pressure application mechanism; and detecting whether fatigue cracks are initiated on the pipeline through a strain difference measured by the strain gage arranged on the pipeline test piece, and determining extension length of cracks according to strain values measured by different strain gages in the circumferential direction to further obtain a relationship between the cyclic load times of the pipeline test piece and the length of the fatigue cracks. The detecting method has the advantages that the crack initiation condition of the submarine pipeline can be predicted by detection on the pipeline test piece, the detecting method is simple and accurate, a submarine pipeline which is not mounted can be detected, and whether the submarine pipeline meets requirements of submarine services can be judged.

Description

technical field [0001] The invention relates to the technical field of bending detection of submarine pipelines, in particular to a detection method and a detection device for the initiation process of bending fatigue cracks of submarine pipelines. Background technique [0002] Submarine pipelines are a type of pressure pipelines, but the difference from ordinary pressure pipelines is that submarine pipelines are subject to impacts from tides, waves, currents, sea ice, and ocean drops, as well as seawater erosion and friction from fishing nets. The role of submarine pipelines makes the probability of failure of the more common pressure pipelines higher and accidents more likely. Among the various defect types that induce pipeline accidents, crack defects in pipelines account for the largest proportion. Therefore, it is necessary to determine the crack damage and structural strength of the structure through detection and testing. Contents of the invention [0003] In orde...

Claims

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Application Information

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IPC IPC(8): G01N3/24
CPCG01N3/24G01N2203/0062
Inventor 邓少旭杨冬平支景波王伟斌赵栋邵永波高莎莎王安鹏梁勇
Owner CHINA PETROLEUM & CHEM CORP
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