This British Standard specifies the inspection and testing procedures, chemical composition, heat treatment and mechanical properties for 3/2 % nickel-chromium-molybdenum steel supplied in the form of tube for aerospace purposes.
BS T 79:1997 history
1997BS T 79:1997+A1:2013 Specification for 2,5% nickel-chromium-molybdenum steel tubes (1160 MPa)
1997BS T 79:1997 Specification for 21/2% nickel-chromium-molybdenum steel tubes (1160 MPa)