Welding issues for the pressure tapping tubes of orifice plates and pressure gauges
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A rather basic question: For the pressure tapping tubes of flow orifice plates and those of pressure gauges, is it necessary to prepare a Welding Procedure Specification WPS in the same way as for pressure pipelines? Generally, the diameter of the fittings is small, around 1/2”, and they are mostly joined by socket welding. What are the welding requirements for different materials (CS, 304L, 316, 321SS, 1.25Cr1Mo, etc.)? How is JB4708 required? Materials like chromium-molybdenum steel also require post-weld heat treatment, which is quite troublesome. I checked the WPS/PQR files; they do not cover such requirements. I would appreciate some guidance from an expert.
1. Instrument pipelines do not fall under the category of industrial pipelines. 2. No industrial welding assessment is required, but the welding materials must be selected properly. 3. The wall thickness of the pressure tapping tubes for instruments is relatively thin; therefore, no heat treatment or non-destructive testing is required. 4. The pressure tapping pipe must undergo pressure and sealing tests (the test pressure shall meet the requirements of the process pipeline).
It’s not necessary, as the regulations state that pipes with a diameter of no more than DN25 do not fall under the category of pressure pipes