ASTM A182
Grade F5
Chrome-Moly Forged Flanges
Why Grade F5 Resists Sulfidation
Grade F5 sits between Grade F22’s 2.25% chromium and Grade F9’s 9% chromium on the same chrome-moly ladder — but it earns a distinct reputation in refinery service for a reason beyond simple temperature capability. Its 5% chromium content provides genuine, well-documented resistance to sulfidation corrosion, a specific high-temperature degradation mechanism where sulfur compounds in crude oil and its derivative streams attack steel surfaces.
Sulfidation resistance improves broadly with increasing chromium content across this whole family, but Grade F5’s 5% level is a commonly referenced, practical threshold in refinery metallurgy selection guides — high enough to provide meaningfully better sulfidation resistance than the F11/F22 range, while remaining more moderate in cost and welding complexity than the 9% chromium of Grade F9.
That makes Grade F5 the grade refinery process engineers frequently reach for specifically when sulfur-bearing crude or sour hydrocarbon service is the driving concern — as distinct from Grade F22, which is more commonly selected purely for general high-temperature strength and hydrogen service without sulfidation being the primary driver.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our Grade F5 flanges and forged fittings are manufactured and verified by chemical composition and mechanical testing under our ISO 9001:2015 quality system.
A Note on Product Scope
ASTM A182 covers forged flanges, fittings, valves, and similar forged pressure-part components — it does not govern nuts or stud bolts, which fall under ASTM A194 and ASTM A193 respectively. If your requirement is for matching stud bolts to pair with F5 flanges, please let us know — we’re glad to discuss suitable matching alloy or stainless fastener grades alongside your F5 forgings.
Where This Grade Genuinely Applies
Genuine Sulfidation Resistance
5% chromium content resists sulfur-compound attack in high-temperature refinery streams.
Genuine Oxidation Resistance & Creep Strength
The same well-established mechanisms found across the whole chrome-moly family.
Practical Refinery Threshold
A recognized, commonly-referenced chromium level in refinery metallurgy selection practice.
Verified Mechanical Properties
Batch testing confirms genuine chromium and molybdenum content and mechanical properties.
Choosing Between Related Forged Alloy Grades
Grade F22
2.25% chromium — genuinely capable for general high-temperature and hydrogen service.
View Grade F22 →Grade F5 (This Page)
5% chromium — the practical refinery sulfidation-resistance threshold, between F22 and F9.
You Are HereGrade F9
9% chromium — the highest step on this ladder, for the most demanding sustained high-temperature service.
View Grade F9 →Grade F22 vs Grade F5 — Quick Reference
Confirming whether sulfidation from sulfur-bearing hydrocarbon streams is genuinely the driving concern, versus general high-temperature strength alone. This table is the quick reference we use with buyers before quoting.
| Aspect | Grade F22 | Grade F5 |
|---|---|---|
| Chromium Content | ~2.25% | ~5.00% |
| Molybdenum Content | ~1.00% | ~0.50% |
| Sulfidation Resistance | Moderate | Genuinely higher |
| Best Suited For | General high temperature, hydrogen service | Sulfur-bearing refinery streams |
Grade F5 Specification Details
Nominal Composition
- Chromium 4.00 – 6.00%
- Molybdenum 0.44 – 0.65%
- Carbon ≤0.15%
- UNS Designation K41545
Typical Mechanical Range
- Condition Normalized & Tempered / Annealed
- Service Temperature Elevated to High Range
- Sulfidation Resistance Genuinely Improved
- Creep Strength Genuinely Improved
Forged Components We Manufacture
- Flanges Weld Neck, Slip-On, Blind, Socket
- Forged Fittings Elbows, Tees, Reducers
- Valve Bodies Forged Components
- Custom Forgings On Request
Application Areas
Wherever sulfur-bearing hydrocarbon streams at elevated temperature genuinely make sulfidation resistance the driving material concern.
Refinery Crude & Vacuum Units
distillation piping and flanges
Fluid Catalytic Cracking Units
process piping and fittings
Hydrotreating & Hydrocracking
flanges and valve bodies
Fired Heater Tube Support Systems
components in sour service
Standard Export Documentation
Prepared as standard practice for every Grade F5 flange or forged fitting shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Chemical Composition Report
Confirms actual chromium and molybdenum content fall within the specified Grade F5 range.
Certificate of Conformance
Confirms the shipment matches the purchase order grade/size specification in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
NABL Accredited Test Reports
Independent mechanical, dimensional, and NDT testing available on request.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Internationally Recognised Standards Coverage
Related Grades & Materials
ASTM A182 Grade F22
Our lower-chromium alternative, for general high-temperature service without a sulfidation focus.
View Grade F22 →ASTM A182 Grade F9
Our higher-chromium alternative, for the most demanding sustained high-temperature service.
View Grade F9 →ASTM A194 Grade 8M Nuts
Our chloride-resistant stainless nut grade, for matching fasteners in corrosion-sensitive service.
View Grade 8M Nuts →Stainless Steel Fasteners Manufacturer India
Our broader fastener manufacturing capability across all major carbon, alloy, and stainless grades.
View SS Manufacturer Guide →Sulfur-Bearing
Refinery Streams?
Tell us your service temperature and stream sulfur content — we’ll confirm whether Grade F5 fits, or whether F22 or F9 is the better match, and quote with full documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in