P91 F91 Alloy Steel Flange details
The core standards of P91 alloy are divided into three parts: material standards, flange size standards, and corresponding domestic standards. The following is a complete list and key parameters:
1, Material standards (P91/F91)
P91 is 9Cr-1Mo-V-Nb-N martensitic heat-resistant steel, with flange forging grade F91, and core execution:
ASTM A182/A182M F91 (American standard forging, flange main material)
UNS：K90901
Chemical composition (wt%): C 0.08-0.12; Mn 0.30–0.60; Si ≤0.50; Cr 8.0–9.5; Mo 0.85–1.05; V 0.18–0.25; Nb 0.03–0.07; N 0.03–0.07; S/P ≤0.020.
Mechanical properties: Tensile strength ≥ 620MPa; Yield ≥ 415MPa; Elongation rate ≥ 20%; Hardness 190-248HBW.
Heat treatment: normalizing+tempering (normalizing 1040-1080 ℃; tempering 730-800 ℃).
ASME SA182 F91 (equivalent to A182, commonly used for pressure vessels/boilers).
Corresponding pipe material: ASTM A335 P91; Board: SA387 Gr91 Cl2.
Domestic counterparts: GB/T 10Cr9Mo1VNbN (GB/T 5310, NB/T 47008).
2, Flange size and RTJ sealing surface standard
ASME B16.5 (Core, NPS 1/2–24",Class 150–2500)
WN: Welding flange; RTJ: Ring connection surface (R/RX/BX type metal ring gasket).
Pressure rating: Class 150/300/600/900/1500/2500 (suitable for high temperature and high pressure).
ASME B16.47 (Large Diameter NPS 26-60 ", A/B Series).
Domestic flange standards: GB/T 9112-2010 (equivalent to B16.5), HG/T 20615 (American standard system).
3, Common combinations and tags
Standard combination: ASME B16.5+ASTM A182 F91+RTJ.
Example of flange marking: WN 12 "Class 1500 RTJ A182 F91.
4, Key applications and temperature
Applicable temperature: ≤ 620 ℃ (for thermal power main steam, hydrogenation equipment, high temperature and high pressure pipelines).
Prohibited: Non high temperature creep conditions (high cost), mixed with carbon steel/ordinary stainless steel.
5, Supplementary standards (non-destructive testing/welding)
Testing: ASME SA-388 (forging UT), ASTM A609 (MT/PT).
Welding: NB/T 47014 (welding evaluation), DL/T 695 (power station pipe fittings).
Tianjin Baode Steel Co.,Ltd is one of biggest factory in North of China to produce alloy steel,stainless steel and carbon steel pipe fittings.
