This specification covers carbon and high-strength low-alloy steel structural shapes@ plates@ and bars and quenched and tempered alloy steel for structural plates intended for use in bridges. Grades 250 [36]@ 345 [50]@ 345S [50S]@ or 345W [50W] are also included in ASTM A36/A36M@ A572/A572M@ A992/A992M@ A588/A588M@ and A514/A514M. When the supplementary requirements of this specification are specified@ they exceed the requirements of A36/A36M@ A572/A572M@ A992/A992M@ A588/A588M@ and A514/A514M. Grades 345W [50W]@ HPS 345W [HPS 50W]@ HPS 485W [HPS 70W]@ and HPS 690W [HPS 100W] have enhanced atmospheric corrosion resistance (Section 13.1.2). Product availability is shown in Table 2. Grade HPS 485W [HPS 70W] or HPS 690W [HPS 100W] shall not be substituted for Grade 250 [36]@ 345 [50]@ 345S [50S]@ 345W [50W]@ or HPS 345W [HPS 50W]. Grade 345W [50W] or HPS 345W [HPS 50W] shall not be substituted for Grade 250 [36]@ 345 [50]@ or 345S [50S] without agreement between the purchaser and supplier. When the steel is to be welded@ it is presupposed that a welding procedure suitable for the grade of steel and intended use or service will be utilized. See Appendix X3 of ASTM A6/A6M for information on weldability.