Tesco Steel & Engineering forges ASTM A182 F316H blind flanges — UNS S31609, the creep-rated member of the 316 family — to ASME B16.5 Class 150–2500 from ½″ to 24″ NB and to ASME B16.47 up to 60″. Like F304H it inverts the low-carbon logic — carbon held at 0.04–0.10% with an enforced minimum, the carbides pinning the structure against creep and earning separate allowable-stress lines above ~525 °C — and unlike it, F316H keeps the 2–3% molybdenum: creep strength and chloride resistance for the hot streams that carry both. Melted to order (no dual-cert with F316L), solution annealed at minimum 1040 °C with rapid cooling. Facings: BLRF, BLFF or BLRTJ. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM A182 F316H · UNS S31609 · EN 1.4919High Carbon 0.04–0.10% · Minimum EnforcedCreep-Rated + Molybdenum RetainedSustained 525–815 °C DutyASME B16.5 ½″–24″ · Class 150–2500RF · FF · RTJ FacingsEN 10204 3.1 / 3.2 · ISO 9001:2015
The hot-service 316. A solid forged disc of high-carbon molybdenum stainless (UNS S31609) with no bore, closing pipes, valves and nozzles in sustained 525–815 °C duty. The defining feature is a carbon minimum: 0.04–0.10% — guaranteeing the carbides that resist creep and earning the grade its own allowable-stress lines — while the retained 2–3% molybdenum carries chloride resistance into the hot world. Room-temperature mechanicals match F316 (515/205 MPa); the difference shows at 650 °C. Melted to order, solution annealed min. 1040 °C. Dimensions per ASME B16.5 / B16.47 in RF, FF and RTJ facings; EN 10204 3.1 certified.
Also searched as: 316H blind flange, SS 316H blind, S31609 blind, SA-182 F316H blind (the ASME boiler-code twin), 1.4919 blind (the EN counterpart) — all refer to the product on this page. See also the stainless steel hub, the F316H slip on flanges, siblings F316 / F316L / F304H blind flanges, and the facing pages BLRF / BLFF / BLRTJ.
The Carbon Inversion — With Molybdenum Kept
The H logic is the same as on the F304H page — where L removes carbon to protect welds, H guarantees it for creep — with one addition that defines this grade:
Carbides Pin the Structure
At creep temperatures, finely distributed carbides anchor grain boundaries against the slow sliding that is creep — the guaranteed 0.04% minimum keeps them coming for the design life, earning the H grade its own hot allowable-stress lines.
Molybdenum Rides Along
Unlike F304H, the 2–3% molybdenum stays — pitting and crevice resistance for hot streams that carry chlorides, plus a modest edge in hot strength. The choice between the two H grades is usually exactly this column.
One Mechanism, Two Reputations
The same precipitation hot service exploits is called sensitization and condemned in aqueous duty — the H grade is that trade made deliberately, with service kept hot where it pays.
Never with L — windows don't overlap; melted to order
The no-dual-cert rule matters at purchase. L caps carbon at 0.030%; H demands at least 0.04% — no melt satisfies both, so H-grade blinds are melted deliberately against the order. If the line class says F316H, the certificate must say F316H: substituting standard 316 in a creep-rated joint is a specification break whose consequence arrives slowly, years into service.
Hot high-class refinery circuits — ring softer than groove
ASTM A182 F316H Blind Flange Specifications
ASTM A182 F316H Blind Flanges are available in the following specifications:
Material Grade
ASTM A182 F316H (UNS S31609); ASME SA-182 dual-certifiable; EN 1.4919 counterpart — melted to order
Heat Treatment
Solution annealed, minimum 1040 °C, rapid cool — mandatory; furnace record on certificate
Size
1/2"NB to 24"NB per ASME B16.5; 26"–60" per ASME B16.47; EN 1092-1 to order
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Facings
Raised Face (BLRF), Flat Face (BLFF), Ring Type Joint (BLRTJ) with groove per B16.20
Service
Sustained 525–815 °C creep duty with chloride-bearing streams — separate H-grade allowables
Surface Finish
Pickled & passivated or natural machined — no paint; segregated stainless handling throughout
Modifications
NPT-tapped centre (hydrotest / vent / drain / gauge), lifting provisions — machined & certified at the works
Testing
Tension & chemistry per heat — carbon and molybdenum reported explicitly; PMI routine; grain size where specified
Certification
EN 10204 3.1 (standard) / 3.2 witnessed
Why F316H Blind Flanges Are Specified
Creep Strength the Certificate Can Prove
The enforced carbon minimum separates a rated H-grade closure from a hopeful standard-316 one — written in the code's own allowable-stress lines.
Chlorides Handled Hot
The retained molybdenum is the reason to pick this H grade: hot streams that also carry chlorides get creep strength and pitting resistance in one certificate.
The Matching-Metal Principle, Hot
A 316H header deserves a closure on the same rating lines — blind in the line's own H grade keeps creep life and certificates uniform across the joint.
Works-Controlled Metallurgy
Deliberate melt, 1040 °C anneal, rapid cool, carbon and molybdenum on the certificate — the qualities creep service demands, documented.
Know the Siblings
General chloride duty: F316. Welded chloride duty: F316L. Chloride-free hot duty: F304H. Stabilized hot: 321H/347H to order. Facings: BLRF / BLFF / BLRTJ.
Specification Notes — Getting the H Grade Right
Three details buyers miss.H means melted to order: no dual-cert stock covers an F316H requirement — allow lead time, and insist the certificate reports carbon explicitly. Mind the boundaries of the trade: after long hot service the metal is sensitized by design — the molybdenum does not protect a sensitized grain boundary, so shutdown chemistry needs managing, and alternating hot/corrosive duty should consider stabilized 321H/347H. Below 525 °C it buys nothing: the H premium is for the creep band — everyday chloride duty belongs to F316/F316L.
How Our F316H Blind Flanges Are Manufactured
1
Deliberate melt — the S31609 heat is ordered with the carbon window enforced; spectro verification confirms 0.04–0.10% carbon and 2–3% molybdenum before forging begins.
2
Forging — hot-forged into the solid disc blank with full heat traceability and segregated stainless handling.
3
Solution anneal — minimum 1040 °C with rapid cooling; furnace charts retained against the heat number.
4
Machining & facing — faces, OD and drilling to ASME B16.5 / B16.47; RF serrations, flat face or RTJ groove gauged per B16.20; NPT taps machined where ordered.
5
Testing & marking — tension test and chemistry with carbon reported explicitly; PMI on every piece; grain-size determination where specified; permanent marking of standard, grade F316H, size, class and heat number.
6
Certification & packing — EN 10204 3.1 MTC (3.2 witnessed on request); pickled and passivated, faces protected, palletised or crated sea-worthy.
Where F316H Blind Flanges Are Used
The permanently hot corners where chlorides also feature: refinery heater and furnace headers, hot-oil and transfer lines with chloride-bearing streams, hot chemical process, and steam-adjacent duties specifying the molybdenum grade. Production below:
Machined Stainless Blind Flange — Face DetailLarge-Diameter Flange — Ring Groove Machined
F316H Blind Flange Dimensions
Blind dimensions are class-governed — identical across material grades. Full charts:
An ASTM A182 F316H blind flange is a solid forged disc of high-carbon austenitic stainless steel — UNS S31609, the creep-rated member of the 316 family — drilled to the standard bolt pattern with no bore, used to close pipes, valves and vessel nozzles in sustained high-temperature service: refinery heaters and hot headers, hot chemical process, furnace-adjacent piping above roughly 525°C. It keeps 316's molybdenum, so it also carries chloride resistance into that hot world. Dimensions follow ASME B16.5 from ½ inch to 24 inch and ASME B16.47 beyond, in raised face, flat face and ring joint facings.
What does the H in F316H mean?
High carbon, held deliberately: 0.04-0.10% with a minimum as well as a maximum — the inversion of the L grade's logic. In sustained hot service, carbon is the strengthening agent: it forms the carbides that resist creep, and a melt too lean in carbon quietly lacks the long-term strength the rating tables assume. The H designation guarantees the carbon is there, pairs it with a high-temperature solution anneal, and earns the grade its own allowable-stress lines in the codes above roughly 525°C.
How does carbon buy creep strength?
Through the same carbides that cause trouble elsewhere. At sustained high temperature, finely distributed chromium carbides pin grain boundaries and slow the microstructural sliding that is creep — the identical precipitation that, in aqueous corrosion service, would be called sensitization and condemned. The H grade is the deliberate side of that trade: carbon kept high for strength, service kept hot where intergranular corrosion has no electrolyte to exploit. One mechanism, two reputations — which side you are on is decided by the duty.
F316, F316L or F316H — which one?
By carbon, which is to say by duty. F316 (≤0.08%) is the general-purpose chloride-duty form. F316L (≤0.030%) is the welded-corrosion-duty choice — the most-specified of the three, since chloride duty is usually welded duty. F316H (0.04-0.10%, minimum enforced) is the sustained-hot-service choice — carbon guaranteed for creep strength, melted to order. The three share the molybdenum chemistry otherwise; they diverge exactly where the service does. Our F316 and F316L blind flange pages cover the other corners.
Why can't F316H dual-certify with F316L?
Because their carbon windows do not overlap: L demands ≤0.030%, H demands ≥0.04%. A melt satisfies one or the other, never both — the opposite of the F316/F316L pair, which overlap comfortably. That is why H-grade material is melted deliberately against an order rather than pulled from dual-cert stock, and why an 'H' on the line class means the certificate must say H. Substituting standard 316 in a creep-rated joint is a specification break with a long, slow consequence.
F316H or F304H — which H grade?
By what the hot stream carries. Both are creep-rated 18-8 austenitics with enforced carbon; F316H adds the 2-3% molybdenum, buying pitting and crevice resistance that matters when the hot service is also chloride-bearing — hot brackish streams, chloride-carrying process chemistry, condensing zones — and a modest edge in hot strength. F304H is the economical choice where the hot stream is chloride-free. The line class usually decides by unit licensor habit; our F304H blind flange page covers the plain branch.
What are the mechanical properties of F316H blind flanges?
At room temperature, the standard austenitic set: tensile 515 MPa (75 ksi) minimum, yield 205 MPa (30 ksi) minimum, elongation 30%, reduction of area 50% — A182 sets no hardness limit. The difference lives in the code tables at temperature: above roughly 525°C the H grade carries its own, higher allowable-stress lines, bought by the guaranteed carbon and high-temperature anneal. You buy F316H for what it holds at 650°C, not for what the tensile machine reads at 20°C.
What temperature range does an F316H blind flange cover?
Its home is sustained service between roughly 525 and 815°C — the band where creep governs design and where plain 316's rating lines stop or thin out. The oxidation limit of the composition, around 800-815°C continuous, caps the top. Below 525°C the H grade works but buys nothing; the grades to stock there are F316 and F316L. The cold end of the family belongs to the low-carbon grades — the H grade is the hot specialist.
Does sensitization matter for F316H?
It is accepted by design while the flange lives hot — but it matters at the boundaries. After long service in the carbide-forming range, an H-grade component is sensitized metal, and if the duty later turns aqueous and corrosive (acid cleaning, idle periods with condensate) intergranular attack becomes possible — the molybdenum helps against pitting but not against a sensitized grain boundary. The management is operational: keep hot service hot, control shutdown chemistry, and where hot duty alternates with corrosive exposure consider the stabilized grades 321H and 347H, forged to order.
How is F316H heat treated?
A high-temperature solution anneal — minimum 1040°C with rapid cooling — is mandatory, dissolving the carbon so service can precipitate it usefully, and producing the somewhat coarser grain that benefits creep life. The furnace record travels on the certificate. As with every austenitic, the anneal is works business: field heating and improvisation have no place on a creep-rated component.
What facings are F316H blind flanges made with?
All three: raised face (BLRF) with graphite-filled spiral-wound gaskets typical of hot service, flat face (BLFF) for utility interfaces, and ring type joint (BLRTJ) for hot high-class refinery circuits, the ring chosen softer than the groove. Each facing has its own page on this site. The forging is common to all three; the mating flange governs the choice, and for RTJ the ring number follows from size and class.
Can F316H blind flanges be tapped for testing or instruments?
Yes — fill, vent, drain, gauge and injection taps are machined into the centre of the blind at the works, before final inspection, and certified with the flange. Austenitic stainless work-hardens as it machines, and a creep-rated component deserves works tooling doubly; the tap arrives ready to plug with the anneal undisturbed. State the NPT size on the enquiry.
Where are F316H blind flanges used?
The permanently hot corners of process industry where chlorides also feature: refinery heater and furnace headers, hot-oil and transfer lines with chloride-bearing streams, hot chemical process, and steam-adjacent duties that specify the molybdenum grade by habit. F316H blinds close those lines as isolations, future connections and tapped test blinds — in the line's own creep-rated grade, keeping the joint on the same allowable-stress lines as the pipe.
Which standards cover F316H blind flanges?
The material standard is ASTM A182 grade F316H (UNS S31609), with ASME SA-182 as its boiler-code twin and EN 1.4919 as the European counterpart; dimensions follow ASME B16.5 for ½"-24" and ASME B16.47 for 26"-60", with the stainless rating tables carrying separate H-grade lines at high temperature. A complete specification reads: 'Blind Flange, RF, 6", ASME B16.5 Class 300, ASTM A182 F316H' — and our EN 10204 certificates state grade, heat treatment and carbon explicitly.
Who manufactures ASTM A182 F316H blind flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, forging ASTM A182 F316H / UNS S31609 blind flanges from ½" to 24" NB per ASME B16.5 in Classes 150-2500 and to 60" per ASME B16.47 — melted to order with the carbon minimum enforced, solution annealed at minimum 1040°C with rapid cooling, PMI-verified and certified to EN 10204 3.1/3.2 on every lot — in raised face, flat face and ring joint facings, alongside F316/F316L, F304/F304L/F304H, duplex and nickel-alloy blinds. Exported to more than 50 countries.
