Welding of stainless steel pipelines
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Excuse me :) What is the difference between the intergranular corrosion resistance and stress corrosion resistance of stainless steel pipe materials? Is stabilization heat treatment still required for ultra-low carbon and stable austenitic stainless steel pipes after welding? Are there any such pipeline construction cases in China (for example, in the nuclear industry)?
No one answered this question; I solved it on my own. After reviewing the relevant technical documents (see sht3523-1999), clause 4.5.1 states that for solution and stabilization heat treatments, the test temperature must be above 900 degrees, with rapid cooling required – conditions that are difficult to achieve in actual construction settings. Therefore, in such operating conditions, typical designers or patent agencies recommend the use of ultra-low carbon or stabilized austenitic stainless steels, rather than ordinary austenitic stainless steels, so that only stress-relief treatment and pickling/passivation at temperatures below 900 degrees are carried out, with no requirement for stabilization heat treatment. In fact, in the nuclear industry as well as in some process pipelines operating under high hydrogen pressures, such pipelines often require stabilization heat treatment as per design specifications; however, the effect of performing this stabilization heat treatment on-site is very poor. This question might be a bit off-topic, but I’m just hoping that friends who have had similar experiences can share their insights.
The high-pressure hydrogen-containing media in the hydrogenation unit use process pipelines made of stabilized austenitic stainless steel, which require stabilization heat treatment, a process that can be carried out on-site.