Tesco Steel & Engineering manufactures ASTM A182 F316H long weld neck flanges — both dials turned at once: UNS S31609, W.Nr. 1.4919 equivalent — with ASME B16.5 flange ends in Classes 150–2500 and the barrel made to order. The chemistry marries the site's two running stories: the 0.04–0.10% carbon floor that builds creep-carrying carbides — 304H's logic — on 316's molybdenum frame (2.00–3.00%), for the services where sustained heat above ~525 °C and corrosive, chloride-bearing chemistry arrive together: refinery heaters on sour feeds, hot headers, hot process columns. The supply rule is stricter than any sibling's: melted to order against S31609 — modern dual-certified 316/316L stock sits below the H floor by design and can never substitute. Room-temperature certificate identical to 316 (515/205/30); the difference lives in the creep-range allowables, and the ≥1040 °C solution anneal with rapid cooling is mandatory — the paperwork is the product. One forging, one closing weld with 316H filler, never 316L. Benches stay honest: 316 below, 304H when the chlorides stay away, Incoloy 800H above. Facings: RF / FF / RTJ. Every lot with EN 10204 3.1/3.2 MTC, carbon band certified. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM A182 F316H · UNS S31609 · 1.4919 eq.Both Dials: Creep Carbon + MolybdenumC 0.04–0.10% Floor · Mo 2.00–3.00%Creep Duty Above ~525 °C, Chlorides WelcomeMelted to Order — Never Dual-Certified316H Filler — Never 316LB16.5 Flange Ends · Class 150–2500EN 10204 3.1 / 3.2 · ISO 9001:2015
ASTM A182 F316H Long Weld Neck Flanges — Specifications at a Glance
What is an ASTM A182 F316H Long Weld Neck Flange?
Both dials at once, in the nozzle pattern. An ASTM A182 F316H flange (UNS S31609) whose neck continues as a long, heavy-walled straight barrel — the nozzle itself — bevelled for one closing butt weld at the header or shell. Carbon 0.04–0.10% — the creep floor — on 316's molybdenum frame: for services where heat above ~525 °C and chlorides arrive together. Room-temperature certificate identical to 316 (515/205/30); the difference lives in the creep-range allowables. Melted to order — dual-certified stock sits below the floor; welded with 316H, never 316L. Supplied solution annealed ≥1040 °C with rapid cooling — mandatory — records on the MTC. Flange ends per ASME B16.5, Classes 150–2500; barrel length and bore stated by you. EN 10204 3.1 on every lot.
The rule of the bench: 304H when the hot stream is clean, 316H when the chlorides come with the heat, the stabilised pair when the duty cycle bites, and the Incoloy band when stainless itself runs out.
What the Double Purchase Buys
Creep Allowables, Certified in the Chemistry
The 0.04% floor guarantees the carbide-forming carbon is in the metal — the H grade's higher creep-range allowables exist because the certificate proves the mechanism, exactly as on the 304H and F91 benches.
Pitting Margin Through the Wet Excursions
The 2.00–3.00% molybdenum defends the film when shutdown washes, dew-point crossings and chloride condensates turn a hot system briefly wet — the excursions that find 304H.
A Nozzle Where Both Audits Meet
Hot joints are creep audit items; chloride joints are pitting audit items — the one-forging LWN deletes a weld from nozzles that would otherwise carry both liabilities at once.
Segregated, Traceable, Honest About Lead Time
Melted to order against S31609, never pulled from the dual-certified shelf — carbon band on the MTC, PMI-backed segregation, and the H-grade lead-time story stated up front.
Specification Notes — Getting F316H Long Weld Necks Right
Three honest notes.The substitution error is silent and doubled here: dual-certified 316/316L stock passes every receiving inspection with an identical certificate and fails years later as accelerated creep — order F316H by name, S31609 on the line, carbon band on the MTC. The filler carries the same rule:316H, never 316L — an L-grade weld in an H-grade system is the error in miniature. And buy the double purchase only where both halves work: clean hot streams are 304H's economical franchise, cool chloride duty is 316's — F316H earns its price where the heat and the chemistry genuinely overlap.
How Our F316H LWN Flanges Are Manufactured
1
Forging — each piece individually forged from certified high-carbon heats melted or sourced against UNS S31609 and kept segregated from general stainless stock, with the barrel integral — no welded build-ups.
2
Solution annealing — 1040 °C minimum with rapid cooling, mandatory: carbides dissolved, the deliberate carbon returned to solution, the grain structure set; records retained against the heat number.
3
Verification — chemistry per heat with the 0.04–0.10% carbon band certified explicitly; mechanicals per heat; grain size measured and reported where the specification invokes it.
4
Machining — flange end to ASME B16.5; barrel turned to pattern (standard / HB / equal) and bored to the ordered schedule or drawing; RF serrations, flat face or RTJ groove per B16.20; weld end bevelled 37.5°.
5
Testing & marking — PMI-checked on every piece — the molybdenum line and the segregated H stock together make F316H unmistakable on the shelf; marked with grade, size, schedule and heat number.
6
Certification & packing — EN 10204 3.1 MTC carrying the carbon band, anneal records and grain size where specified (3.2 witnessed on request); H-grade WPS guidance naming 316H fillers; faces and bevels protected, packed sea-worthy.
Where F316H LWN Flanges Are Used
Where the heat and the chemistry overlap: refinery fired heaters and their crossover and header connections on sour, naphthenic and chloride-bearing feeds, hot separator and transfer-line nozzles in corrosive hydrocarbon service, hot chloride-bearing process columns, and the elevated-temperature exchanger and thermowell connections that plain 316 should not hold for decades and 304H should not face chemically — from ~525 °C toward the austenitic scaling limits near 815 °C. Production and supply below:
Stainless Long Weld Necks — Machined at Our WorksLong Weld Neck — Heavy Barrel, Bevelled Weld EndDN600 RF Long Weld Neck — Large Diameter, B16.5 Drilling
F316H LWN Flange Dimensions
Flange-end dimensions are class-governed per ASME B16.5 (ratings per the austenitic material group, elevated-temperature tables governing); barrel length and bore per order. Full class-by-class charts:
Seven elements — temperature and medium together confirm the double purchase:
1
Size & standard — e.g. 6″ NB ASME B16.5.
2
Pressure class & facing — 150#–2500#; RF, FF or RTJ with ring number.
3
Barrel length — overall, face to weld end: 150 / 230 / 300 mm stock or any stated length.
4
Barrel bore & pattern — pipe schedule to match or finished bore in mm; standard, heavy barrel or equal barrel; weld-end prep if non-standard.
5
Grade line & service — ASTM A182 F316H by name (UNS S31609); design metal temperature and medium stated — they confirm the double purchase against 316 below, 304H sideways and the Incoloy bench above; any grain-size requirement named.
6
Certification — EN 10204 3.1 with the carbon band and anneal records (our standard) / 3.2 witnessed.
An ASTM A182 F316H long weld neck flange is a forged high-carbon molybdenum austenitic stainless steel flange — UNS S31609, W.Nr. 1.4919 equivalent — whose neck continues as a long, heavy-walled straight barrel that is itself the nozzle, bevelled at its far end for one closing butt weld made out at the header, vessel or exchanger shell. F316H turns both of this site's dials at once: carbon is held in a deliberate 0.04-0.10% band whose floor builds the creep-carrying carbides — the 304H logic — while the frame keeps 316's 2.00-3.00% molybdenum, so the grade holds sustained heat above roughly 525°C in services where chlorides and corrosive chemistry arrive with it. Flange ends follow ASME B16.5 in Classes 150 to 2500; the barrel is machined to the ordered length and bore. Supplied solution annealed at 1040°C minimum with rapid cooling — mandatory — with the carbon band certified.
How does a long weld neck differ from a standard weld neck flange?
Geometry and mission. A standard weld neck's hub tapers quickly down to the pipe's outside diameter and wall, ending in a weld bevel a few centimetres from the flange face — it is built to butt-weld to pipe and continue as a piping run. A long weld neck keeps a full-section straight barrel for its entire length: no taper to pipe dimensions, wall far heavier than the matching schedule, length made to order. The mission follows the shape — the LWN is not a fitting on a pipe run but a nozzle in its own right, projecting through insulation, vessel walls or exchanger channels, with the butt weld relocated to the shell side where the fabricator wants it. In one certified forging it replaces the weld neck flange, the pipe nipple and one whole circumferential weld.
Why does 316H exist — what do both dials buy together?
A niche neither parent covers alone. 304H carries creep duty economically, but its 18-8 frame has no molybdenum — hot service whose stream also carries chlorides, naphthenic acids or aggressive condensates finds it. Plain 316 carries the molybdenum, but modern low-carbon heats have nothing to precipitate — above roughly 525°C its allowables taper and some code paths simply require the H chemistry. 316H is the intersection: the 0.04% carbon floor guarantees the carbide-forming mechanism that holds creep-range allowable stresses, and the 2.00-3.00% molybdenum keeps the pitting margin through shutdowns, washes and dew-point excursions that turn a hot system briefly wet and corrosive. Refinery heaters on sour or chloride-bearing feeds are the classic address: hot enough for the H, dirty enough for the moly — one grade answering both.
Why is F316H melted to order — and never dual-certified?
Because the market's stainless shelf has moved below its floor. Modern 316 production runs carbon under 0.030% to dual-certify with 316L — comfortably beneath 316H's 0.04% minimum — so the H grade cannot be pulled from general stock, re-marked or substituted: the carbide-forming carbon the creep allowables depend on simply is not in a dual-certified heat. The substitution error runs exactly as it does on the 304H page: identical room-temperature certificates, every receiving inspection passed, and the shortfall expressing itself only as accelerated creep years into hot service. So F316H is melted or sourced against its own UNS number S31609, ordered by name, kept segregated with PMI-backed traceability, and certified with the carbon band shown explicitly. Plan the procurement accordingly — H-grade material has a lead-time story that everyday 316 does not.
What is the chemical composition of ASTM A182 F316H?
Carbon 0.04-0.10% — the defining band, floor and ceiling both mandatory — manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%, sulphur ≤0.030%, chromium 16.0-18.0%, nickel 10.0-14.0%, molybdenum 2.00-3.00%. Beside plain 316 the frame is identical — the balanced recipe of chromium, nickel and molybdenum unchanged — and the entire difference is the carbon column, floored where the everyday grade drifts low. Beside 304H the frame is the difference: the molybdenum line that buys pitting margin at the same creep-carbon setting. Chemistry is verified per heat with the carbon band certified explicitly, PMI-confirmed, and travels on the EN 10204 3.1 MTC.
What are the mechanical properties of F316H long weld neck flanges?
Solution annealed: tensile strength 515 MPa (75 ksi) minimum, yield strength 205 MPa (30 ksi) minimum, elongation 30% minimum — numbers deliberately identical to plain 316, and deliberately not the point. The H grade's commercial reason lives in the design tables: through the creep range its allowable stresses hold usefully above the low-carbon grades', and elevated-temperature code paths lean on the H chemistry by name. As across the site's hot benches, the two-ceilings honesty applies: at 316H's working temperatures the gasket system and bolting are engineering questions of their own, and the flange metal is rarely what retires first. Hardness sits comfortably low; grain size — coarser structures creep slower — is reported on the certificate where the project specifies it.
Where do F316H LWN flanges serve?
Where the heat and the chemistry arrive together: refinery fired heaters and their crossover and header connections on sour, naphthenic or chloride-bearing feeds, hot separator and transfer-line nozzles in corrosive hydrocarbon service, hot chloride-bearing process columns, and the elevated-temperature exchanger and instrument connections that plain 316 should not hold for decades and 304H should not face chemically. The service band runs from roughly 525°C, where the H purchase starts paying, toward the austenitic family's scaling limits around 815°C. The LWN construction suits the habitat doubly: hot nozzles are where designers count welds — every joint at creep temperature is a long-term audit item — and chloride-side nozzles are where they count crevices; the one-forging pattern answers both at once.
Why is the solution anneal mandatory — 1040°C minimum with rapid cooling?
Because the H grade's mechanism must start from a clean sheet. The anneal above 1040°C dissolves the carbides the mill process precipitated, puts the deliberate carbon back into solution, and sets the grain structure the creep properties assume; the rapid cool then races the carbon past the sensitising band so it arrives in service unspent, ready to precipitate usefully — on the grain boundaries, at temperature, over years — rather than wastefully in the cooling curve. Skip or botch the cycle and the certificate's promise is hollow: the room-temperature numbers survive, the creep behaviour does not. Our MTCs carry the anneal temperature and cooling record against the heat number, because on an H grade the heat-treatment paperwork is the product — the same rule the site's F91 and 304H pages state for their benches.
Doesn't the carbon floor invite sensitisation in the weld zone?
Yes — the same open-eyed trade the 304H page describes, with one 316-flavoured nuance. Welded or held in the sensitising band, 316H will precipitate grain-boundary carbides more readily than low-carbon stock; at the grade's design temperatures that precipitation is the strengthening mechanism, and the classic aqueous intergranular attack rarely finds the conditions it needs. The nuance: 316H's habitats include services that cycle wet — shutdown washes, dew-point excursions, chloride-bearing condensates — which is precisely why the grade carries molybdenum, defending the pitting side while the carbon works the creep side. Where a duty genuinely combines creep temperatures with frequent aggressive wet excursions, the stabilised H grades — 321H and 347H, their carbon locked to titanium and niobium — are the honest alternative, and both benches are available from our works. State the full duty cycle and the bench places the grade.
How is the closing weld on an F316H LWN made?
With austenitic ease and the H-grade non-negotiable: the filler carries the carbon and the molybdenum both. Procedures are the friendly stainless kind — no preheat beyond dryness, no PWHT, ordinary technique and interpass control — but consumables must be the carbon-floored 316H class, never standard 316L: an L-grade weld in an H-grade system is the substitution error in miniature, a low-carbon, lower-allowable zone planted exactly where service stresses concentrate. Qualification on coded hot work follows the project's elevated-temperature rules, heat-tint is removed by pickling or passivation where the chloride side of the duty demands it, and the closing weld at the header or shell inherits the system's own qualified H-grade procedure. WPS guidance travels with every supply, filler class stated.
How are the barrel length and bore of a LWN specified?
Two numbers that belong on every enquiry. Length: measured overall from the flange face to the weld end — 150 mm (6"), 230 mm (9") and 300 mm (12") are the common stock lengths, and any length machines to order; state it explicitly, because 'long' is not a dimension. Bore: the barrel is drilled and bored to order — most commonly to match the inside diameter of the connecting pipe schedule, sometimes cylindrical special bores for level bridles, instrument standpipes or restriction work; state the schedule or the finished bore in millimetres. Add the weld-end preparation (standard 37.5° bevel unless told otherwise) and the nozzle is fully defined.
When does F316H hand off — down the dials or up the benches?
Down by temperature: below roughly 525°C metal temperature the straight 316 grades serve and dual-certified stock is the economical buy — H there is creep capability paid for and never used. Sideways by chemistry: where the hot stream carries no chlorides or corrosive condensates, 304H does the same creep work without the molybdenum's price; and where creep duty meets frequent sensitising excursions, the stabilised pair 321H and 347H lock their carbon instead. Up by temperature: when the stainless creep bench runs out — scaling and allowables both fading toward 815°C — the site's Incoloy 800H/800HT pages carry the same carbon-band logic into nickel-iron-chromium territory. Heat without corrosion belongs to the chrome-moly staircase and F91. State metal temperature, medium and duty cycle; the benches sort themselves.
What sizes and pressure classes do F316H LWN flanges come in?
Flange ends follow ASME B16.5 from ½" to 24" NB in Classes 150, 300, 400, 600, 900, 1500 and 2500 — with the full class-by-class LWN dimension charts on this site — and larger diameters forge to order against B16.47 or drawing dimensions, with EN 1092-1 drilling machined on the same barrels. The F316H order book follows the hot end of its habitat: refinery heater and hot-header work concentrates in Classes 300-1500, where the austenitic material group's elevated-temperature ratings do the governing and heavy-barrel patterns serve the high-temperature nozzle loads. State size, class, barrel length and bore together — the four numbers define the forging — and our quotation returns price, unit weight and delivery per class, with the H-grade lead-time story stated up front.
What details are needed to get an accurate F316H LWN flange quotation?
Seven elements plus commercial terms: (1) size and dimensional standard — e.g. 6" NB ASME B16.5; (2) pressure class — 150 to 2500; (3) facing — RF (the default), FF or RTJ with ring number; (4) barrel length overall, face to weld end — 150/230/300 mm stock or any stated length; (5) barrel bore — pipe schedule to be matched or finished bore in millimetres, with pattern (standard, heavy barrel, equal barrel) and weld-end prep if non-standard; (6) the grade line — ASTM A182 F316H by name, UNS S31609 — with the design metal temperature and the medium stated so the double purchase is confirmed against 316 below, 304H sideways and the Incoloy bench above, and any grain-size requirement named; (7) certification — EN 10204 3.1 with the carbon band and solution-anneal records (our standard) or 3.2 witnessed. Add quantity and destination; quotations normally within 24 hours, with the melted-to-order lead time quoted honestly.
Who manufactures ASTM A182 F316H long weld neck flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing ASTM A182 F316H long weld neck flanges with B16.5 flange ends from ½" to 24" NB (larger to order) in Classes 150-2500, in standard, heavy-barrel and equal-barrel patterns — each forged individually from certified high-carbon heats melted or sourced against UNS S31609 and kept segregated from general stainless stock, solution annealed at 1040°C minimum with rapid cooling and records retained, machined with the barrel bored to the ordered schedule or drawing, bevelled for the closing weld, PMI-checked, and marked with grade, size, schedule and heat number. Supplied with EN 10204 3.1/3.2 certification carrying the carbon band and grain size where specified, and H-grade WPS guidance naming 316H fillers — alongside the 316/316L rungs below, the 304H and stabilised benches beside, the Incoloy 800H/800HT pages above, and the complete long weld neck range. Exported to more than 50 countries.
