Material Grade Specification

Alloy Steel F91 Flanges — 9Cr-1Mo-V Creep Resistant

Alloy steel F91 flange manufacturer, Mumbai. UNS K91560 9Cr-1Mo-V creep-resistant steel for ultra-supercritical power steam lines to 650°C. Quote in 30 min.

Material Specification & Overview

ASTM A182 F91 is a 9% Chromium, 1% Molybdenum alloy steel micro-alloyed with Vanadium and Niobium, providing exceptional creep rupture strength and thermal fatigue resistance at operating temperatures up to 650°C.

UNS DesignationK91560 (F91)
Governing StandardASTM A182 / ASME SA-182 Grade F91

Chemical Composition (wt %)

Governing specification limits per ASTM / ASME standards. Actual values provided on EN 10204 3.1 MTC.

ElementSpecification Limit / Composition
Chromium (Cr)8.0 - 9.5%
Molybdenum (Mo)0.85 - 1.05%
Vanadium (V)0.18 - 0.25%
Niobium (Nb)0.06 - 0.10%
Nitrogen (N)0.030 - 0.070%

Mechanical Properties

PropertySpecification Limit
Yield Strength415 MPa (60 ksi) min
Tensile Strength585 - 760 MPa
Service Temp RangeUp to 650°C (1,200°F)

Pressure-Temperature Rating Reference

Service TempClass 150Class 300Class 600Class 900
Ambient (-29 to 38°C)290 psi750 psi1500 psi2250 psi

Primary Industry Applications

Ultra-supercritical power plant main steam circuits
Combined cycle gas turbine (CCGT) heat recovery steam generators (HRSG)
High-temperature refinery hydroprocessing units
High-energy steam piping systems

Related Products & Industry Guides

Frequently Asked Procurement Questions

Q: Why is post-weld heat treatment (PWHT) critical for F91 flanges?

A: F91 forms a fully martensitic structure upon cooling. Strict PWHT (typically 730°C to 760°C) is mandatory to temper the martensite and restore impact toughness.

Direct Factory Pricing

Get Quote in 30 Minutes for Alloy Steel F91 Flanges

Written commercial offer with Mill Test Certificate guarantee.

Get in touch

Fill this form and get a quote in 30 minutes — guaranteed

Let our experts take over from here!

🏆 ISO 9001:2015
🤝 ONGC • Tata • L&T
📜 MTC 3.1 Provided
⚡ 30 Min Response