HASTELLOY® X Alloy Welded Steel Pipe | ASTM B619, ASTM B775, ASME SB619, ASME SB775 Overview of HASTELLOY® X Alloy Welded Pipe HASTELLOY® X alloy (UNS N06002, W86002) is a nickel-chromium-iron-molybdenum superalloy designed for exceptional performance in high-temperature and corrosive environments. Renowned for its oxidation resistance, high-temperature strength, and fabricability, HASTELLOY® X is widely