Welded steel pipe for low-pressure fluid transportation (GB/T3092-1993) is also known as general welded pipe, commonly known as black pipe.

It is a welded steel pipe used to transport general low-pressure fluids such as water, gas, air, oil and heating steam, and other purposes. The wall thickness of steel pipe joints is divided into ordinary steel pipes and thickened steel pipes; The form of the pipe end is divided into non-rebar pipe (plain pipe) and rebar pipe by manufacturer.

The specifications of steel pipes are expressed in terms of nominal diameter (mm), which is an approximation of the inner diameter. It is customary to use inches as 11/2, etc. In addition to being directly used for conveying fluids, welded steel pipes for low-pressure fluid transportation are also widely used as raw pipes for galvanized welded steel pipes for low-pressure fluid transportation.