Differences Between ASTM A358 and ASTM A312

astm a358 / a358m is standard specification for electric-fusion-welded austenitic chromium-nickel stainless steel pipe for high-temperature service and general applications

this specification covers electric-fusion-welded austenitic chromium-nickel stainless steel pipe suitable for corrosive or high-temperature service, or both, or for general applications. the pipes shall be sorted into five different classes. class 1 pipes shall be double welded by processes employing filler metal in all passes and shall be completely radiographed. pipes of class 2 shall be double welded by processes employing filler metal in all passes with no radiography. both class 3 and class 4 pipes shall be single welded except that the weld pass of the latter exposed to the inside pipe surface may be without the addition of filler metal. pipes of class 5 shall be double welded by processes employing filler metal and shall be spot radiographed. weld defects shall be repaired by removal to sound metal and rewelding. subsequent heat treatment shall be as required on the original welds. the finished pipes shall be subjected to transverse tension test, transverse guided-bend weld test, and hydrostatic test.

astm a312 / a312m is standard specification for seamless, welded, and heavily cold worked austenitic stainless steel pipes

this guide covers standard specification for seamless, straight-seam welded, and cold worked welded austenitic stainless steel pipe intended for high-temperature and general corrosive service. several grades of steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, chromium, nickel, molybdenum, titanium, columbium, tantalum, nitrogen, vanadium, copper, cerium, boron, aluminum, and others. all pipes shall be furnished in the heat-treated condition in accordance with the required heat treating temperature and cooling/testing requirements. tensile properties of the material shall conform to the prescribed tensile strength and yield strength. the steel pipe shall undergo mechanical tests such as transverse or longitudinal tension test and flattening test. grain size determination and weld decay tests shall be performed. each pipe shall also be subjected to the nondestructive electric test or the hydrostatic test.