ASTM A182 F304H Slip On Flanges — High Temperature SS 304H Manufacturer
Tesco Steel & Engineering forges ASTM A182 F304H slip on flanges — the high-temperature version of stainless steel 304, with carbon controlled to 0.04–0.10% so the creep strength that design codes demand above 538 °C is guaranteed, not accidental — to ASME B16.5 Class 150–2500 from ½″ to 24″ NB, larger patterns to order. The stainless flange of refinery heaters, steam superheat and furnace-adjacent piping, rated to 815 °C in the B16.5 tables, with the stabilised hot grades 321, 347 and the 25Cr-20Ni 310 from the same forge. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM A182 F304H · SA182 · S30409C 0.04–0.10% Guaranteed · 1.4948ASME B16.5 Class 150–2500½″ – 24″ NB · SORFCreep Duty >538 °C · Rated to 815 °CEN 10204 3.1 / 3.2 MTCISO 9001:2015 · Exported Worldwide
ASTM A182 F304H Stainless Steel Slip On Flange — Raised Face (SORF)
What is an ASTM A182 F304H Slip On Flange?
F304H = 304 with the carbon locked in.ASTM A182 F304H (UNS S30409) controls carbon to 0.04–0.10% — a range with a deliberate minimum, because carbon is what pins austenitic grain boundaries against creep. ASME B16.5 allows 304's stresses above 538 °C only when C ≥ 0.04% — the H grade makes that contractual. As a slip-on, it installs with two fillet welds, E308H consumables, no preheat, no PWHT. The stainless of heaters, superheat and hot flue duty to 815 °C.
Also searched as: SS 304H slip on flange, 304H SORF flange, high temperature stainless slip on flange, SA182 F304H slip on flange, S30409 slip on flange, 1.4948 slip on flange — all refer to the product on this page.
Rule of thumb: within the 304 family the selector is carbon — L for welded corrosive duty, standard for general service, H for creep-range heat. Hotter or dirtier still, the stabilised grades and 310 take over.
ASTM A182 F304H (UNS S30409) Chemical Composition
C
Mn
Si
P
S
Cr
Ni
Fe
0.04-0.10
2.00 max
1.00 max
0.045 max
0.030 max
18.0-20.0
8.0-11.0
Bal
Values in weight % per ASTM A182 for UNS S30409. The carbon range with its 0.04% minimum is the grade's defining feature — it is the creep-strengthening element the code's elevated-temperature stress tables are conditioned on. Otherwise the recipe is standard 18-8.
ASTM A182 F304H Mechanical Properties
Tensile Strength, MPa (ksi)
Yield Strength, Min, MPa (ksi)
Elongation % min (2")
Reduction of Area % min
515 (75) min
205 (30) min
30
50
Identical to standard 304 at room temperature — the H grade's value is invisible at ambient. It lives in the creep-rupture strength above 538 °C, supported by the guaranteed carbon and a solution anneal run hot enough to develop the coarser grain creep resistance favours. Values demonstrated per heat on the EN 10204 certificate.
A182 F304H Slip On Flange Specifications
ASTM A182 F304H Slip On Flanges are available in the following specifications:
Material
ASTM A182 F304H / ASME SA182 F304H (UNS S30409)
Size
1/2"NB to 24"NB per ASME B16.5; larger patterns to order
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Facing
Raised Face (SORF) — default; Flat Face or RTJ where the piping class specifies
Heat Treatment
High-temperature solution anneal per ASTM A182 — develops the creep-favouring grain; thermal record retained
Service
Creep-range duty above 538 °C — rated to 815 °C in the ASME B16.5 tables
Installation
Two fillet welds (hub + bore), pipe set back 1/8"; E308H/ER308H consumables, no preheat, no PWHT
Below 538 °C
The H grade buys nothing — standard F304 or F304L is the economical choice
Certification
EN 10204 3.1 (standard) / 3.2 witnessed, qualifying carbon on every certificate
Equivalent Grades of ASTM A182 F304H
Standard
Werkstoff Nr.
UNS
JIS
EN (working equivalent)
SS 304H
1.4948
S30409
SUS 304H
X6CrNi18-10
ASME SA182 F304H is the boiler-code twin. System partners: ASTM A312 TP304H pipe and A403 WP304H fittings — the hot-stainless trio of creep-range piping. Certificates always state the actual grade forged with the qualifying 0.04-0.10% carbon.
Why A182 F304H Slip Ons Are Specified
The Code's Grade Above 538 °C
B16.5 and the boiler code condition 304's elevated-temperature stresses on C ≥ 0.04% — F304H is the supply that guarantees it on paper.
Creep Strength by Design
Guaranteed carbon plus a hot solution anneal for coarse grain — the two levers of austenitic creep resistance, both locked in at the forge.
Rated to 815 °C
The B16.5 stainless tables run to 815 °C and 304's oxidation resistance holds to ~870 °C continuous — genuine furnace-adjacent territory.
Austenitic Simplicity Retained
No preheat, no PWHT, standard E308H practice — creep-range metallurgy without the chrome-moly fabrication burden.
Know the Handoffs
Below 538 °C: 304/304L. Hot duty with wet shutdowns: stabilised 321/347. Hotter still: 310. Critical RT-mandated lines: F304H weld necks.
How Our A182 F304H Slip On Flanges Are Manufactured
1
Forging — cut billet of certified A182 F304H heat — carbon verified 0.04-0.10% — is hot-forged into the flange blank, keeping full heat traceability from raw material to despatch.
2
Solution annealing — run at the high end of the range per ASTM A182 to dissolve carbides and develop the coarser grain that creep resistance favours; furnace record retained.
3
Machining — hub, faces and bolt holes to ASME B16.5; the bore machined slightly over pipe OD per the slip-on tolerance.
4
Facing & finish — SORF raised face with serrated stock finish, flat face or RTJ groove; pickled and passivated on request.
5
Testing & marking — mechanical and chemical verification against the heat, grain size where the order specifies, then permanent marking of grade, size, class and heat number.
6
Certification & packing — EN 10204 3.1 MTC with the qualifying carbon (3.2 witnessed on request), export-packed for sea freight.
Where A182 F304H Slip On Flanges Are Used
The creep range of stainless duty: refinery fired-heater and FCC circuits, steam superheater and reheater connections, HRSG hot sections, hot air and flue-gas systems, catalytic reformer auxiliaries, and furnace-adjacent process lines running 538-815 °C. Our hot-grade stainless production below:
A182 F304H Flange — Machined & MarkedStainless Flanges — In Production at Our WorksA182 F304H Series A Flange — RTJ Facing, Class 1500
A182 F304H Slip On Flange Dimensions
F304H slip-on dimensions follow the ASME B16.5 slip-on tables — identical for every material. Full charts by class:
Example: “Slip On Flange, 4″ NB, ASME B16.5 Class 300, RF, ASTM A182 F304H, EN 10204 3.1 — 20 pcs.” Quotations normally within 24 hours with price, unit weight and delivery.
ASTM A182 F304H Slip On Flanges — Frequently Asked Questions
What is an ASTM A182 F304H slip on flange?
It is a slip-on flange forged from ASTM A182 F304H — the high-temperature version of stainless steel 304 (UNS S30409), with carbon controlled to 0.04-0.10% rather than merely capped — dimensioned to ASME B16.5. The flange slides over the pipe end and is secured with two fillet welds, and the guaranteed carbon minimum secures the creep strength that design codes demand above 538 °C. It is the stainless flange of refinery heaters, steam superheat and furnace-adjacent piping.
What does the H in 304H mean — and why a carbon minimum?
H is high temperature, and the mechanism is carbon. In the creep range, carbon is austenitic stainless steel's load-bearing element — it pins grain boundaries against slow deformation — so ASME B16.5 and the boiler code allow 304's higher elevated-temperature stresses only when carbon is at least 0.04%. Standard 304 merely caps carbon at 0.08% and might melt anywhere below it; 304H guarantees the 0.04-0.10% window, making the creep strength contractual rather than accidental.
What is the chemical composition of ASTM A182 F304H?
Per ASTM A182 for UNS S30409: carbon 0.04-0.10% (a controlled range with a deliberate minimum — the grade's defining feature), manganese 2.00% max, silicon 1.00% max, phosphorus 0.045% max, sulphur 0.030% max, chromium 18.0-20.0% and nickel 8.0-11.0%. Apart from the carbon window it is the same 18-8 recipe as standard 304.
What are the mechanical properties of A182 F304H slip on flanges?
Per ASTM A182: tensile strength 515 MPa (75 ksi) minimum, yield strength 205 MPa (30 ksi) minimum, elongation 30% minimum in 2" and reduction of area 50% minimum — the same room-temperature numbers as standard 304. The grade's value is invisible at ambient: it lives in the creep-rupture strength above 538 °C, supported by the carbon window and a solution anneal run hot enough to develop the coarser grain that creep resistance favours.
What is the difference between 304H and 304?
The carbon minimum. Standard 304 caps carbon at 0.08% with no floor — a lean heat might carry 0.02% and lose the elevated-temperature stress values the code tables attach to carbon of 0.04% and above. 304H locks the 0.04-0.10% window, plus a high-temperature solution anneal for creep-favouring grain. Room-temperature properties are identical; the difference only appears — decisively — above 538 °C, where 304H is the grade the code actually permits.
Can 304H and 304L be dual-certified like 304/304L?
No — they are chemical opposites. 304L demands carbon at or below 0.030%; 304H demands at least 0.04%. No heat can satisfy both, which is exactly the point: the L grade sacrifices carbon for weld-zone corrosion immunity, the H grade keeps it for creep strength. What is possible is 304/304H dual certification, since the H window sits inside standard 304's cap. Choose by service temperature: L below, H above, and never interchange them.
What temperature range can F304H slip on flanges handle?
Its working territory is roughly 538-815 °C. ASME B16.5 rates the stainless groups to 815 °C, and 304H carries the code's full elevated-temperature stresses through that range, with 304's oxidation resistance holding to about 870 °C in continuous service. Below 538 °C the H grade works but buys nothing — standard 304 or 304L is the economical choice there. Hotter or more demanding still, the 25Cr-20Ni grade 310 takes over.
Does 304H sensitize — and does it matter?
Yes, it sensitizes readily — with 0.04%+ carbon, chromium carbides will precipitate during welding and during service in the 425-815 °C band. In hot dry service this is accepted: intergranular corrosion is an aqueous mechanism, and there is no electrolyte inside a heater line at 600 °C. The caution belongs to shutdowns and cleaning — a sensitized system exposed to wet corrosive conditions can suffer weld-line attack. Where that risk governs, the stabilised grades 321H and 347H exist precisely to serve heat with sensitization resistance.
When are 321H or 347H specified instead of 304H?
When the service combines creep temperatures with corrosion or cyclic exposure that sensitization would compromise. 321H (titanium-stabilised) and 347H (niobium-stabilised) tie up carbon as harmless Ti/Nb carbides, keeping chromium in solution while retaining the H-grade creep minimums — the classic choice for refinery heater outlets and cyclic hot lines that also see wet shutdowns. Where the hot service is clean and dry, plain 304H does the job for less. We forge all three.
How is an A182 F304H slip on flange welded to pipe?
With two fillet welds — hub outside, bore inside, pipe set back 1/8" (3 mm) — using matching E308H/ER308H consumables, whose controlled carbon preserves the weld metal's creep strength. No preheat and no PWHT, as for all austenitics. The heat-affected zone will sensitize; in the hot dry services 304H is bought for, that is accepted practice. Weld procedures for creep-range lines are qualified accordingly under B31.3/B31.1.
What is the equivalent of ASTM A182 F304H in other standards?
ASME SA182 F304H is the boiler-code twin; UNS S30409 the designation; the European working equivalent is X6CrNi18-10 (Werkstoff 1.4948), the hot-service 304 of EN pressure standards; JIS practice uses SUS 304H. System partners specified alongside it: ASTM A312 TP304H pipe and A403 WP304H fittings — the hot-stainless trio. Certificates always state the actual grade forged with the qualifying carbon.
Are slip on flanges allowed in creep-range service?
Within limits. Slip-on flanges are permitted by the piping codes and serve on lower-criticality hot lines — drains, vents, utility and auxiliary connections — but many piping classes restrict creep-range and cyclic main lines to weld neck flanges, whose full-penetration butt weld can be radiographed and handles thermal fatigue better than fillet welds. Follow the piping class: where it allows a slip-on, an F304H slip-on delivers the metallurgy at lower flange and fit-up cost.
What sizes and classes are A182 F304H slip on flanges available in?
From ½" to 24" NB per ASME B16.5 in Classes 150 through 2500, with larger patterns forged to order. The H grade is project material rather than shelf stock — forged against the order from certified 0.04-0.10% carbon heats with the high-temperature solution anneal — so standard sizes normally dispatch within a few weeks with EN 10204 3.1 certification. State the required delivery on the enquiry and we confirm the schedule with the quotation.
What details are needed to get an accurate A182 F304H slip on flange quotation?
Five elements plus commercial terms: (1) size and standard — e.g. 4" NB ASME B16.5; (2) pressure class — 150 through 2500; (3) facing — SORF (raised face) default, flat face or RTJ where specified; (4) grade — ASTM A182 F304H, with grain size or supplementary requirements where the project specifies; (5) certification — EN 10204 3.1 or 3.2. No pipe schedule is needed for the slip-on bore. Add the quantity and destination and we return price, weight and delivery.
Who manufactures ASTM A182 F304H slip on flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, forging ASTM A182 F304H stainless steel slip on flanges from ½" to 24" NB per ASME B16.5 — alongside standard 304, 304L and the hot-service grades 321, 347 and 310 — with the qualifying carbon on every certificate, full heat traceability and EN 10204 3.1/3.2 certification on every lot. Flanges are marked with grade, size, class and heat number and export to more than 50 countries.
