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Method for determining defects of multilayer binding vessel by acoustic emission

A determination method and acoustic emission technology, applied in the direction of material analysis using acoustic emission technology, can solve the problems that there is no analytical formula for calculating the stress analysis formula of the deep girth weld of multi-layer wrapped high-pressure vessels

Inactive Publication Date: 2010-05-19
SHANDONG UNIV +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] (2) Defect simplification technology
[0029] In view of the influence of the laminate gap and the deep girth weld, there is no stress analysis formula that can calculate the deep girth weld of the multi-layer wrapped high-pressure vessel

Method used

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  • Method for determining defects of multilayer binding vessel by acoustic emission
  • Method for determining defects of multilayer binding vessel by acoustic emission
  • Method for determining defects of multilayer binding vessel by acoustic emission

Examples

Experimental program
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Effect test

Embodiment 1

[0080] A segmented multi-layer wrapped urea synthesis tower, hereinafter referred to as the urea tower, with an inner diameter of r 0 =700mm, the effective wall thickness B without deducting the wall thickness of inner lining and blind layer e =110mm, consisting of inner lining, blind layer, n=12 strength layers, a total of 14 layers, except the first strength layer is 16MnR, the rest of the strength layer material is 15MnVR. From the inside to the outside, the inner lining is 8mm thick, the blind layer is 6mm thick, the first strength layer is 12mm thick, the second to tenth strength layers are 8mm thick, and the eleventh to twelfth strength layers are 6mm thick. The longitudinal welds between the layers of the urea tower are staggered from each other, and the girth welds are deep girth welds reaching the entire wall thickness. The operating conditions of the urea tower are: the maximum working pressure is 19.6MPa, the design pressure is p=20MPa, and the maximum working temp...

Embodiment 2

[0091] As in Example 1, a segmented multi-layer wrapped urea synthesis tower, hereinafter referred to as the urea tower, has an inner diameter of r 0 =700mm, the effective wall thickness B without deducting the wall thickness of inner lining and blind layer e =110mm, consisting of inner lining, blind layer, n=12 strength layers, a total of 14 layers, except the first strength layer is 16MnR, the rest of the strength layer material is 15MnVR. From the inside to the outside, the inner lining is 8mm thick, the blind layer is 6mm thick, the first strength layer is 12mm thick, the second to tenth strength layers are 8mm thick, and the eleventh to twelfth strength layers are 6mm thick. The longitudinal welds between the layers of the urea tower are staggered from each other, and the girth welds are deep girth welds reaching the entire wall thickness. The operating conditions of the urea tower are: the maximum working pressure is 19.6MPa, the design pressure is p=20MPa, and the maxi...

Embodiment 3

[0102] A segmented multi-layer wrapped ammonia synthesis tower, referred to as "ammonia tower", with an inner diameter of 500mm and a wall thickness of 85mm. The working temperature is about 200°C. The longitudinal welds between the layers of the ammonia tower are staggered from each other, and the girth welds are deep girth welds reaching the entire wall thickness.

[0103] The review of equipment archives before the test and the routine non-destructive testing of the inner and outer surfaces of the container and the welds of the nozzles are the same as in Example 1, and the maximum laminate gap is still δ 1 ~δ 11 = 0.1 mm.

[0104] The first step is the same as the first embodiment, check the maximum allowable test pressure ratio, and conduct pressure and acoustic emission tests. When the test pressure reached 1.25 times the design pressure, it was found that a group of acoustic emission source events in the cylinder section near the upper end of the ammonia tower develop...

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Abstract

The invention relates to the technical field of safety assessment of pressure vessels with defects, in particular to a method for determining defects of a multilayer binding vessel by acoustic emission. Acoustic emission detection is carried out according to the structural features of the vessel so as to determine the defects. The method comprises the following steps of: (1) activating defects under overpressure, synchronously monitoring the defects in the vessel by acoustic emission, determining the overpressure during activating the defects and positioning the activated defect parts; (2) simplifying activated defects which cannot be determined by ultrasonic phased array rechecking according to the development direction of an acoustic emission event; (3) obtaining the stress distribution of the simplified defect parts by utilizing finite element calculation or a nomogram obtained on the basis of the finite element calculation so as to ensure that the simplified defects are on a maximum stress wall surface vertical to the simplified defects; and (4) based on defect simplification conditions, the stress of the simplified defect parts and material fracture toughness, reversely reasoning nominal initial sizes and tolerance sizes of the defects according to a fracture mechanics theory. The method has reliable detection means and reasonable simplification process and provides a foundation for the safety assessment of multilayer binding vessels.

Description

1. Technical field [0001] The invention relates to the technical field of remaining life assessment and safety assessment of pressure vessels, in particular to an acoustic emission determination method for defects in multi-layer wrapped vessels. 2. Background technology [0002] Multi-layer wrapping structure (also known as laminate wrapping structure) is one of the typical structures of high-pressure vessels, and is widely used in the fields of chemical industry and petrochemical industry. Ammonia synthesis tower and urea synthesis tower, the core equipment in fertilizer production, usually adopt multi-layer wrapping structure, especially the urea synthesis tower has high working parameters and strict working conditions, and the materials contained in it are extremely corrosive. The typical features of the multi-layer wrapped urea synthesis tower are: the inner side in direct contact with the material is a urea-grade stainless steel lining with a thickness of 8 to 10 mm, an...

Claims

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Application Information

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IPC IPC(8): G01N29/14
Inventor 王威强宋明大陈学东李爱菊范志超徐书根杨铁成曹怀祥李庆领吴俊飞
Owner SHANDONG UNIV
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