Issues regarding material selection for GB3091 welded steel pipes
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In Table A.1 of GB/T 20801.2-2020, the welded steel pipes specified in GB3091 are divided into two categories: 2.2 welded pipes (ERW) and 2.4 plate-welded pipes (EFW/SAW). The allowable stresses for these two categories differ slightly; it is necessary to specify which category should be used in the material lists provided in the pipeline construction drawings as well as in the ordering requirements； However, in the standard GB/T 3091-2015 “Welded steel pipes for low-pressure fluid transportation”, the manufacturing processes are classified into three types: longitudinal high-frequency electric welding, longitudinal submerged arc welding, and spiral submerged arc welding. This classification differs from that in GB20801; furthermore, the ordering specifications and pipe markings do not mention ERW and EFW/SAW at all ； The difference between the two standards might cause problems when ordering and purchasing welded steel pipes, right?
Both welded pipes and plate-welded pipes differ in terms of raw materials used and manufacturing processes. It needs to be specified in the order. If it’s not mentioned in the construction drawings or material schedule, it’s best to communicate with the design firm or the client. Different types of pipes have different applicable conditions.
Thank you for your reply. In the design of large-diameter pressure pipes, there are usually no specific requirements regarding the raw materials used for the pipes (coils or plates). However, due to differences in allowable stresses, it is necessary to clearly define the design requirements. According to GB3091, it isn’t required to specify the type of raw material used; therefore, it’s difficult to determine whether the purchased steel pipes meet the design specifications.