are mainly used to transport fluids under pressure. In addition to ensuring the strength and stiffness that meet the corresponding requirements, they are also required to ensure tightness. That is, the steel pipes are required to undergo hydraulic tests one by one before leaving the factory. For pressure pipelines, the media they transport are often flammable, explosive, toxic, corrosive, temperature- and pressure-sensitive media, so steel pipes should be used for fluid transportation. In actual engineering design, procurement and construction, it is often found that structural steel pipes are mixed with or replace steel pipes for fluid transportation, which affects the quality, causes hidden dangers or causes accidents, which is not allowed.

GB/T3{{10}}91 "Galvanized Welded Steel Pipe for Low-Pressure Fluid Transportation" and GB/T3092 "Welded Steel Pipe for Low-Pressure Fluid Transportation" standard steel pipes are generally furnace welded steel pipes and sometimes made by resistance welding). In addition to the required inspection of steel pipes for fluid transportation, In addition to the project, only bending test requirements are attached, so the manufacturing and inspection requirements for this type of steel pipe are relatively low. Their specifications range from 1/8" to 6", with wall thicknesses ranging from ordinary grade to thickened grade. Material grades include Q195A, Q215, and Q235A. They are suitable for applications with design temperatures ranging from 0 degree to 100C and design pressures ranging from 0 degree to 100 degree . Water and compressed air systems exceeding 0.6MPa.