The full name of ASTM A671 standard is "standard specification for electric-fusion-welded steel pipe for atmospheric and lower temperatures", that is, "standard specification for electric fusion welded steel pipes for atmosphere and low temperature".
This standard is formulated by American Society for Testing and Materials (ASTM), which specifies the technical requirements for electric fusion welded steel pipes with filler metal. These steel pipes are made of pressure vessel quality plates with various analysis and strength grades, which are suitable for high-pressure applications at atmospheric and low temperatures.
Nominally, the standard covers pipes with an outside diameter of 16 inches (400mm) or more and a wall thickness of 1/4 inch (6mm) or more. Other sizes of pipes can be provided if all other requirements are met. In ASTM A671 standard, the grades of steel pipes are classified according to the types of steel plates used, and the categories specify the types of heat treatment performed in the pipeline manufacturing process, as well as whether the welds have undergone radiographic inspection and whether the pipeline has undergone pressure test. For example, category 10 means no specific heat treatment, no radiographic testing, no stress testing; Class 22 indicates heat treatment with stress relief, without radiographic inspection, but with 98.3% pressure test.