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Field welding method of domestic A335 P91 high-pressure thick-wall pipe

A technology of A335P91 and welding method, which is applied to welding equipment, tubular objects, arc welding equipment, etc., can solve the problems of low efficiency of manual welding, affect the construction period, and restrict the progress of piping, so as to shorten the heat treatment and welding period and reduce labor intensity , Improve the quality of weld seam and the effect of welding efficiency

Inactive Publication Date: 2016-07-06
THE SIXTH CONSTR CO LTD OF CHINA NAT CHEM ENG
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since A335P91 steel is an air-cooled martensitic steel, the plasticity of the steel is low, and the welding performance is poor. Require
The traditional A335P91 steel welding generally adopts: manual argon arc welding GTAW backing, manual arc welding SMAW filling and covering, it is necessary to strictly control the line energy, preheating temperature and interlayer temperature in the welding process, which is harmful to the welding environment and welders. The technical level is extremely high, and the efficiency of manual welding is extremely low, time-consuming and labor-intensive, which seriously restricts the progress of piping and affects the construction period, especially for large-diameter thick-walled pipes

Method used

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  • Field welding method of domestic A335 P91 high-pressure thick-wall pipe

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Example 1, with domestic A335P91 pipeline DN350 As the base metal, the following welding methods are adopted:

[0025] (1) Put the welding part of the pipe to be welded according to the attached figure 1 As shown, it is processed into a double V-shaped groove, the height of the blunt side is 1mm, the angle between the bottom of the groove and the length direction of the pipe is 60±5°, the height is 15mm, the angle between the upper part of the groove and the length direction of the pipe is 78-82°, and Carry out coloring inspection on the groove surface to ensure that the groove has no surface cracks, and clean the surface rust, oil stains, oxides, etc. on the surface of the groove and the 20mm areas on both sides;

[0026] (2) Assemble the two sections of welded pipes to ensure that the gap between the end faces of the butt joints is 3 to 6 mm, the height is flat, and the amount of misalignment is not greater than 1 mm;

[0027] (3) Manual argon arc welding GTAW is u...

Embodiment 2

[0045] Example 2, with domestic A335P91 pipeline DN600 As the base metal, the following welding methods are adopted:

[0046](1) Put the welding part of the pipe to be welded according to the attached figure 1 As shown, it is processed into a double V-shaped groove, the height of the blunt side is 1mm, the angle between the bottom of the groove and the length direction of the pipe is 60±5°, the height is 15mm, the angle between the upper part of the groove and the length direction of the pipe is 78-82°, and Carry out coloring inspection on the groove surface to ensure that the groove has no surface cracks, and clean the surface rust, oil stains, oxides, etc. on the surface of the groove and the 20mm areas on both sides;

[0047] (2) Assemble the two sections of welded pipes to ensure that the gap between the end faces of the butt joints is 3 to 6 mm, the height is flat, and the amount of misalignment is not greater than 1 mm;

[0048] (3) Manual argon arc welding GTAW is us...

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Abstract

The invention provides a field welding method of a domestic A335 P91 high-pressure thick-wall pipe, and belongs to the technical field of welding. A welded part of a welded pipe is processed as a double-V-shaped groove; a process of welding 3 layers for bottoming by using manual argon arc welding GTAW and filling a cover surface by using automatic submerged arc welding SAW is adopted; multi-layer and multi-pass welding is adopted; each layer of welding line sections is decreased; and the welding line crystallization conditions are changed, so that the toughness of a welding joint is improved, an overthick welding bead is prevented from narrowing a heat affected zone, and a softening belt of the welding joint is prevented from generating cracks in long-time operation at high temperature; a small-diameter welding wire with a diameter of not more than 2.5 mm and a low-hydrogen welding agent are adopted to weld to reduce the linear energy in the welding process, so that grains of base metal are refined, and the possibility of generating such defects as air holes and cracks in welding lines is reduced; and compared with a traditional manual welding method, the field welding method effectively shortens the heat treatment and welding period, improves the welding line quality and the welding efficiency, relieves the labor intensity of welders, and saves the construction cost.

Description

technical field [0001] The invention belongs to the field of welding technology, and in particular relates to an on-site welding method for a domestic A335P91 high-pressure thick-walled pipeline. Background technique [0002] A335P91 steel is an improved 9Cr-1Mo steel, mainly adding V, Nb and other alloying elements to the original 9Cr-1Mo martensitic heat-resistant steel, which has good resistance to high temperature oxidation, high temperature steam corrosion and creep resistance performance, can effectively reduce the weight of the structure, and are widely used in large boiler units, piping systems and petrochemical fields. However, since A335P91 steel is an air-cooled martensitic steel, the plasticity of the steel is low, and the welding performance is poor. Require. The traditional A335P91 steel welding generally adopts: manual argon arc welding GTAW backing, manual arc welding SMAW filling and covering, it is necessary to strictly control the line energy, preheating...

Claims

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Application Information

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IPC IPC(8): B23K9/16B23K9/18B23K9/23B23K33/00B23K9/235
CPCB23K9/16B23K9/18B23K9/23B23K9/235B23K33/00B23K2101/06
Inventor 侯晓星卢杰辉秦涛李风刚潘兰兰陈金华王中任刘海生
Owner THE SIXTH CONSTR CO LTD OF CHINA NAT CHEM ENG
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