Low-temperature container
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I would like to ask everyone: for a low-temperature vessel made of 42+3mm 16MnDR material, is preheating necessary during welding? What is the basis?
This post was last edited by zjq1962 on 2020-11-18 at 14:21. GB/T150 does not require preheating before welding, but post-weld heat treatment should be carried out. Standard NB/T47015 specifies a preheating temperature, but it is only of a recommended nature. Preheating is not required as long as pre-welding heating is not specified in the welding procedure qualification.
Thank you, big shot, for sharing – I’ll learn from it*
First, the material of this device consists of a composite plate with a 42-millimeter base layer and a 3-millimeter composite layer. Second, the base layer is usually made of low-carbon steel or low-alloy steel; when its thickness exceeds 25 millimeters, preheating is required. Third, the welding process evaluations carried out in factories are generally conducted under recommended conditions, unless it involves new materials
What is the matrix material? Is it confirmed that the cladding material is 16MnDR? What is the meaning of 3mm 16MnDR in low-temperature operating conditions? Based on the thermal conductivity of metals, your substrate is also in a low-temperature operating condition.
The substrate is 16MnDR, and the cladding is 3mm of 316L
Looking at your company’s welding procedure qualification, if the qualification requires preheating, then preheating is necessary； It’s a mistake not to preheat. If the welding procedure qualification does not specify preheating, then preheating is not required ； If it’s preheated, then it’s wrong.
Post-weld heat treatment is definitely necessary; due to the plate thickness, preheating should also be required