1.1 This specification covers iron-chromium and iron-chromium-nickel alloy castings for heat-resistant service. The grades covered by this specification are general purpose alloys and no attempt has been made to include heat-resisting all This specification covers standards for iron-chromium and iron-chromium-nickel alloy castings of general purpose grades (Grades HF, HH, HI, HK, HE, HT, HU, HW, HX, HC, HD, HL, HN, and HN) applicable in heat-resistant services. Alloys shall be produced