Regarding the welding of 15Cr5Mo pipes
Thread Content
According to the standard SH3520-91, the preheating temperature for pipes with a thickness of 12 mm or more is required to be between 150–250 degrees Celsius. But is preheating still necessary for pipes with a thickness less than 12 mm? For post-weld heat treatment, materials with a thickness of 10 mm or more require a temperature of 650–700 degrees Celsius ； Is post-weld heat treatment still required for those with a thickness of less than 10 mm as well?
For pipes smaller than 12 mm, pre-heating before welding is not required, nor is post-weld heat treatment necessary.
There is no need for preheating or heat treatment
For those smaller than the standard size, preheating and heat treatment are not required.
Post-weld heat treatment is required for all thicknesses
Personally, I think this post can be closed now. SH3520-91 has been replaced by SH3520-2015; for preheating, refer to Table 7.3.1 in Section 7.3 for the preheating temperatures, and for post-weld heat treatment, refer to Table 10.1 in Section 10 for the specifications regarding post-weld heat treatment of pipes.