How to perform pre-weld and post-weld heat treatment for TP321 pipelines after long-term exposure to hydrogen gas
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After the TP321 pipeline has been exposed to hydrogen for an extended period, its welds need to be repaired; so how should the heat treatment be carried out before and after welding? What are the detailed steps? I hope someone with more knowledge can answer; thank you!
Tempering is carried out after welding to remove hydrogen.
I would like to know the detailed steps, such as the heating rate, constant temperature, and duration for hydrogen removal before welding, whether stabilization treatment is required after welding, and how to carry out that treatment
TP321 pipelines require post-welding stabilization heat treatment: Steel grade, Heating temperature (°C), Heating rate (°C/h), Holding time (h), Cooling rate (°C/h). For TP321, the temperature is 900±25 °C; the heating rate should be adjusted appropriately when the temperature is below 300 °C, while it is 150 °C/h when the temperature is above 300 °C. Above 2,700°C, the cooling rate is 150°C/h; below 700°C, it cools naturally.
I haven’t been on the forum for a long time; I just saw your reply today. Thank you so much!