What are ASTM A182 F11 and F22 alloy steel flanges used for?

ASTM A182 F11 (1.25% Cr, 0.5% Mo) and F22 (2.25% Cr, 1% Mo) are chrome-moly alloy steel flanges for elevated temperature service. F11 is rated to 593°C and F22 to 649°C in continuous service — used in steam lines, reformer effluent piping, and high-temperature hydrocarbon service in Saudi Aramco refineries and gas plants. PWHT (post-weld heat treatment) is mandatory for both grades. F91 (9Cr-1Mo-V) is for ultra-high-temperature service above 649°C.

What sizes of ASTM A182 flanges do you stock in Saudi Arabia?

Gulf Union Ozone stocks ASTM A182 F304L and F316L stainless steel flanges in ASME B16.5 pressure classes 150 to 1500 for sizes NPS ½" to 24". F11 and F22 chrome-moly alloy flanges are stocked in Class 150 to 900, NPS ½" to 20". All types include weld neck, slip-on, blind, and socket weld configurations. Non-stocked sizes (F91 ultra-high temp, Class 2500, or very large bore above 24") are procured to order with 6–12 week lead time. Contact us via RFQ for stock availability confirmation.

ASTM A182 Flanges Saudi Arabia F304 F316

Grade Selection Guide

ASTM A182 Flange Grades — Which Grade for Your Project?

ASTM A182 covers a wide range of forged stainless steel and alloy steel flange grades. The correct grade depends on operating temperature, corrosion environment, and Saudi Aramco project specifications. Use this guide to select the right A182 grade for your piping system.

Grade	UNS / Common Name	Temp Range	Key Properties	Typical Application	In Stock
F304	UNS S30400 / 18-8 SS	−196°C to 816°C	18% Cr, 8% Ni. General corrosion resistance. Standard weldable grade.	Utility piping, food-grade, low-chloride process	✓
F304L	UNS S30403 / Low-C 304	−196°C to 816°C	Carbon max 0.03%. No sensitization risk after welding. No PWHT required.	As-welded assemblies; marine utilities, water systems	✓
F316L	UNS S31603 / Low-C 316	−196°C to 816°C	2-3% Mo added. Superior chloride pitting resistance. Low carbon (0.03% max).	Aramco offshore, marine, brackish water, chemical service	✓
F11 (Cl.2)	UNS K11597 / 1.25Cr-0.5Mo	Up to 593°C	Chrome-moly alloy. High temp strength. PWHT mandatory.	Steam lines, refinery effluent, moderate high-temp service	✓
F22 (Cl.3)	UNS K21590 / 2.25Cr-1Mo	Up to 649°C	Higher Cr-Mo content vs F11. Excellent creep resistance. PWHT mandatory.	Refinery/gas plant high-temp piping, hydrocracker	✓
F91	UNS K90901 / 9Cr-1Mo-V	Up to 649°C+ (creep)	Vanadium-modified 9Cr. Superior creep above 649°C. Strict PWHT (740–760°C).	Power plant steam, ultra-high-temp reformer service	Inquiry

All grades: ASTM A182 · ASME B16.5 · EN 10204 3.1 MTCs · SAEP-347 compatible · Request quote →

Material Selection

Austenitic Stainless vs Chrome-Moly Alloy — Choosing the Right A182 Grade for Aramco Projects

ASTM A182 covers two fundamentally different material families, each suited to distinct service conditions in Saudi Aramco oil, gas, and petrochemical facilities:

Austenitic Stainless Steel (F304, F304L, F316, F316L)

Preferred where corrosion resistance is the primary concern — seawater cooling circuits, chloride-containing process streams, cryogenic service (down to −196°C), and food/pharmaceutical utilities. F316L's molybdenum addition makes it the default choice for offshore and marine service in Saudi Aramco specifications. No post-weld heat treatment (PWHT) required for L-grade material.

Chrome-Moly Alloy Steel (F11, F22, F91)

Preferred where elevated temperature strength is the primary requirement — refinery steam lines, hydroprocessing reactors, high-pressure steam generators. Chrome-moly alloys maintain yield strength at temperatures that would cause carbon steel to creep. PWHT is mandatory after welding to prevent hydrogen embrittlement and relieve residual stresses.

NACE MR0175 Sour Service — Stainless A182 Consideration

Austenitic stainless F304L and F316L are generally acceptable for sour service per NACE MR0175 when hardness is ≤22 HRC (solution-annealed condition). F22 requires controlled hardness and PWHT to meet NACE limits. Verify with project metallurgist for H₂S partial pressures > 0.3 kPa. Sour service materials guide →

SAEP-347 Alloy Flange Coverage

SAEP-347 Annex 4 includes material numbers for stainless and alloy steel flanges. Verify your project's Bill of Materials for the specific 6000XXXXXX material number — do not substitute grades without engineering approval.

View all 59 SAEP-347 material numbers →

PWHT Requirements — Alloy Grades

F304L / F316L: No PWHT required (L-grade)
F11 (Cl.2): PWHT 675–760°C · hold 1h/25mm
F22 (Cl.3): PWHT 675–760°C · hold 1h/25mm
F91: PWHT 740–760°C · strict soaking times

Always verify PWHT requirements with your welding engineer and the relevant ASME B31.3 or B31.1 code.

EN 10204 3.1 MTCs — All Grades

Every ASTM A182 flange order from Gulf Union Ozone ships with EN 10204 Type 3.1 Mill Test Certificates — heat number, full chemical analysis, and mechanical test results from the original forge mill. Required for Saudi Aramco Goods Receipt inspection.

Available Configurations

ASTM A182 Flange Types — ASME B16.5 Configurations in Stock

Weld Neck (WNRF / WNRTJ)

Highest integrity connection — long tapered hub transfers stress from flange to pipe. Used on high-pressure, high-temperature service, and anywhere full radiographic weld inspection is required. Raised Face (RF) and Ring Type Joint (RTJ) facing available.

Slip-On (SORF)

Pipe slips through the flange bore and is double-fillet welded inside and out. Lower stress concentration than weld neck. Used in lower-pressure applications and where initial fit-up flexibility is needed. Raised Face standard.

Blind (BL)

Closes the end of a piping system or vessel nozzle. Allows future access without cutting. Used on isolation valves, vessel manholes, and at the end of process lines requiring periodic inspection. Available in all A182 grades.

Socket Weld (SWRF)

Small-bore (NPS ½\" to 2\") connection. Pipe inserted into socket bore, then fillet welded. Used on high-pressure small-bore piping where butt welding is impractical. Raised Face standard for ASME B16.5.

Threaded (THRF)

NPT-threaded bore for screwed connections. Used on instrument taps, utility systems, and low-pressure applications not requiring welded connections. Available in F304L and F316L stainless.

RTJ (Ring Type Joint)

Grooved face for ring gasket sealing — used in high-pressure, high-temperature service where raised-face gasket integrity is insufficient. Available as weld neck RTJ in F304L, F316L, F11, F22. RTJ flange guide →

FAQ

See also: stainless steel pipe fittings (ASTM A403)
class="section-title">ASTM A182 Flange Questions — Answered

What is the difference between ASTM A182 F304L and F316L flanges?

Both F304L and F316L are low-carbon austenitic stainless steel flanges per ASME B16.5. F304L (18% Cr, 8% Ni) provides general corrosion resistance for standard applications. F316L adds 2–3% molybdenum, providing significantly better resistance to chloride pitting and crevice corrosion — making F316L the standard choice for Saudi Aramco offshore, marine, seawater cooling, and brackish water service. The 'L' (low carbon) designation in both grades prevents sensitization during welding, eliminating the need for PWHT.

What are ASTM A182 F11 and F22 alloy flanges used for in Aramco projects?

F11 (1.25Cr-0.5Mo) and F22 (2.25Cr-1Mo) are chrome-moly alloy steel flanges for elevated temperature service in refinery and gas plant piping. F11 is rated to 593°C for steam lines and moderate high-temperature hydrocarbon service. F22 extends to 649°C for hydrocracker effluent, reformer piping, and power generation steam systems. Both grades require post-weld heat treatment (PWHT) after welding to prevent hydrogen embrittlement. NACE MR0175 compatibility →

Are ASTM A182 flanges SAEP-347 compatible?

Yes. ASTM A182 stainless (F304, F304L, F316, F316L) and alloy (F11, F22, F91) flanges are compatible with Saudi Aramco SAEP-347 Annex 4 material requirements for alloy and stainless steel piping components. Gulf Union Ozone supplies all A182 flanges with EN 10204 Type 3.1 MTCs — actual chemical analysis, mechanical test results, and heat number traceability. See the full SAEP-347 Annex 4 material numbers →

What sizes of ASTM A182 flanges are stocked in Saudi Arabia?

Gulf Union Ozone stocks ASTM A182 F304L and F316L in ASME B16.5, Classes 150–1500, NPS ½″–24″. F11 and F22 alloy flanges stocked in Classes 150–900, NPS ½″–20″. All configurations: weld neck (RF and RTJ), slip-on (RF), blind, and socket weld. Non-stock sizes (F91, Class 2500, NPS above 24″) are procured to order — 6–12 week lead time. Contact via RFQ form for specific stock confirmation.

ASTM A182 Flanges · F304L · F316L · F11 · F22 · F91 · ASME B16.5 · Jeddah Stock

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ASTM A182 Stainless Steel & Alloy Flanges — F304L, F316L, F11, F22, F91