Abstract: Classification of post-weld heat treatment of the 347H stainless steel was introduced, and the status quo of domestic and foreign standards of post-weld heat treatment for austenitic stainless steels was analyzed. At present, domestic and foreign standards have different provisions on the post-welding heat treatment of the 347H stainless steel pipes. The NB/T 10068—2018 standard proposes that the operating temperature and thickness range should be used as the implementation conditions of post-weld heat treatment of the 347H stainless steel, which provides guidance for the post-welding heat treatment of the 347H pressurized pipe used in hydrogen production plant and has certain reference significance. But some of the provisions of the standard are not perfect, including some problems in ferrite measurement sequence, ferrite content qualified value and ferrite measurement method. So it is suggested to adjust the measurement of ferritic content of weld to before post-weld heat treatment, remove the lower limit of ferrite number of 3 FN after solution and stabilization heat treatment, add the qualified value requirement of ferrite content of E(R)16.8.2 cladding metal, and define the detection method of ferrite content. At the same time, the NB/T 10068—2018 standard is not perfect on the implementation conditions of post-welding stabilization heat treatment, so it is suggested that the exemption conditions for post-welding heat treatment should be set in combination with engineering practice experience and foreign advanced standards. For thin-walled workpieces with operating temperature ≥500 ℃ and welded joints with small constraint degree, the post-welding heat treatment should be exempted, so as to maintain the scientific and advanced nature of the standard. The NB/T 10068—2018 standard does not fully disclose the related patent information, thus the patent information disclosure should be done well subsequently to prevent intellectual property hijacking of standards.

Key words: 347H stainless steel, hydrogen production unit, post-weld heat treatment, reheat cracks, standards