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Welding process of large-sized liquefied natural gas storage tank

A technology of liquid natural gas and welding process, applied in welding equipment, manufacturing tools, arc welding equipment, etc., can solve problems such as welding difficulties, and achieve the effect of improving welding efficiency, speeding up construction progress, and saving welding materials and labor.

Inactive Publication Date: 2009-04-22
SHANGHAI INSTALLATION ENG GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0017] The technical problem to be solved by the present invention is to provide a large-scale liquefied natural gas storage tank welding process to solve the defect of difficult welding in the prior art

Method used

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  • Welding process of large-sized liquefied natural gas storage tank
  • Welding process of large-sized liquefied natural gas storage tank
  • Welding process of large-sized liquefied natural gas storage tank

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Embodiment 1

[0033] 1. Using AC square wave power supply:

[0034] There are two kinds of power sources for submerged arc automatic welding, DC and AC. With DC power supply, the weld bead can be spread out and the fusion is good. However, when the DC power supply is used for welding, the current is applied in the same direction, and a directional magnetic field will be formed. For 9 The magnetization-sensitive material of %Ni steel is not easy to eliminate once the magnetization is generated. If the residual magnetism exceeds 50 gauss, it will produce arc magnetic deflection and seriously affect the welding quality. In order to solve the magnetization problem of 9% Ni steel, an AC power supply should be selected. .

[0035] However, if the AC power supply uses a sine wave, the width of the arc will be narrowed, the fusion on the upper side of the weld bead will be worse, and the molten pool will be shallower, so the AC sine wave is considered inappropriate.

[0036] Therefore, the AC squa...

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Abstract

The invention relates to a method for welding a large liquified natural gas storage tank. The method uses alternating rectangular wave current for welding with a welding parameter of between 8.156 and 24.32 KJ / cm and the interlayer temperature of energy input of between 18.9 and 24.32 KJ / cm of 300 DEG C, and selects low carbon type nickel-based welding wire. The method overcomes the problem of arc blow in welding, not only can avoid impact on 9 percent Ni steel during carbon gouging, but also can save welding materials and manpower so as to accelerate construction process and improve welding efficiency. Welding with the process can improve the cold temperature flexibility of a macrograin area of a welding zone, avoid generation of brittle tissue of a fusion area, avoid generation of cold and heat crack in welding, has excellent quality of weld joint, and effectively ensure the cold temperature flexibility of 9 percent Ni steel welding joints. The method well control the quality of the weld joint, and ensures the overall quality of the natural gas storage tank.

Description

technical field [0001] The invention belongs to the field of welding, in particular to a welding process for low temperature resistant materials. Background technique [0002] Natural gas, also known as LND, can be liquefied at a low temperature of -162°C. The liquefied volume is only 1 / 600 of the gaseous state. It is suitable for storage tanks and transportation, and it is easy to gasify. Therefore, liquefied natural gas is the most economical for storage tanks and peak shaving s method. [0003] In the extension project of Shanghai Gas Group's No. 5 Ditch LNG Accident Backup Station, there are two 50,000m3 LNG storage tanks, the outer tank is made of prestressed concrete tank wall, lined with carbon steel plate, and the inner tank is welded with 9% Ni steel plate, which is the key to the construction of LNG storage tank Technology, is the welding of 9% Ni steel. The 50,000m3 LNG storage tank is an all-inclusive type storage tank. The outer tank has a prestressed reinforc...

Claims

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Application Information

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IPC IPC(8): B23K9/00B23K9/095B23K33/00B23K9/235B23K9/18B23K101/12
Inventor 倪家利王毅敏袁旭光陈义发秦凯凯江强
Owner SHANGHAI INSTALLATION ENG GRP
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