Abstract
This specification covers carbon and alloy steel castings for pressure-containing and other applications intended primarily for petroleum and gas pipelines in areas subject to low-ambient temperatures. Castings shall be heat treated by normalizing and tempering or liquid quenching and tempering. The steel shall be made by the electric furnace process or other primary processes. Heat and product analyses shall be performed on the material and the chemical composition shall conform to the prescribed values for carbon, manganese, nickel, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, also for residual elements like vanadium, copper, nickel, chromium, molybdenum, and tungsten. Tensile test shall be made and the mechanical properties thus determined shall conform to the required tensile strength, yield strength, elongation, and reduction of area. Charpy V-notch testing shall be done to determine the impact properties on each heat by specimen type like coupons representing the weld deposits and coupons representing the heat-affected zone. Impact properties shall also be determined on both the heat-affected zone of the base metal and the weld metal of the welding procedure qualification test. After machining, each pressure-containing casting shall undergo hydrostatic pressure testing and shall not leak.
Scope
1.1 This specification covers carbon and alloy steel castings for pressure-containing and other applications intended primarily for petroleum and gas pipelines in areas subject to low-ambient temperatures. Castings shall be heat treated by normalizing and tempering or liquid quenching and tempering. All classes are weldable under proper conditions. Hardenability of some grades may limit usable section size.
1.2 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. Inch-pound units are applicable for material ordered to Specification A757 and SI units for material ordered to Specification A757M.
