ASTM A234 Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service Grade: WP91 Chemical Composition, %： C: 008-0.12 Mn: 0.30-0.60 P: ≤0.020 S: ≤0.010 Si: ≥0.20-0.50 Cr: 8.0-9.5 Mo: 0.85-1.05 Ni: ≤0.40 Cu: ≤0.40 V: 0.18-0.25 Nb: 0.06-0.10 N: 0.03-0.07 Al: ≤0.04 Ti: ≤0.01 Zr: ≤0.01 Tensile Requirements： Tensile strength,…