How do you understand the thickness of the welded joint after post-weld heat treatment?
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The last edit to this post was made by Douwan on 2017-11-3 at 14:32. Regarding the post-weld heat treatment of equipment, GB/T 150.4-2011 specifies the thickness of the welded joint (the thickness required for post-weld heat treatment), as shown in the attached diagram. However, there are two different views regarding the red-marked area in Table 5 (the diagram above) where the thickness is greater than 38 mm (with preheating of over 100°C before welding). View A holds that post-weld heat treatment is necessary when the thickness of the welded joint exceeds 32 mm; when it exceeds 38 mm, not only post-weld heat treatment is required, but also preheating before welding； Group B believes that when there is no pre-welding heating, post-weld heat treatment is required for weld joints with a thickness greater than 32 mm; when pre-welding heating is used, post-weld heat treatment is necessary for weld joints with a thickness greater than 38 mm, otherwise it is not required ； Which of these two understandings do you think is correct? The answer reply is available. Answer: B is correct. Reason: In fact, Table 5 in GB/T 150.4-2011 represents some modifications to GB 150-1998 – additional material information was added, and the textual content was converted into tables. The original text from version 1998 of 150 can be seen in the screenshot: With this explanation, are there any doubts left? Guys, make no more mistakes.
When there is no pre-welding heating, post-weld heat treatment is required for weld joints with a thickness greater than 32 mm. When pre-welding heating is used, post-weld heat treatment is necessary for weld joints with a thickness greater than 38 mm; otherwise, it is not required；
Actually, it would be better to add a note to this table, as this could lead to misunderstandings among designers who are not familiar with the design of the 1998 version of the 150.
It seems complicated, but in reality, if pre-welding heating is not carried out, the minimum thickness required for post-weld heat treatment is 32 mm; whereas if pre-welding heating is done according to standards, heat treatment is required only when the thickness exceeds 38 mm
Personally, I think Party B’s opinion is correct
When there is no pre-welding heating, post-weld heat treatment is required for weld joints with a thickness greater than 32 mm. When pre-welding heating is used, post-weld heat treatment is necessary for weld joints with a thickness greater than 38 mm; otherwise, it is not required