Tesco Steel & Engineering manufactures ASTM A182 F316L long weld neck flanges — both fixes in one grade: UNS S31603, W.Nr. 1.4404 — with ASME B16.5 flange ends in Classes 150–2500 and the barrel made to order. The recipe answers the corrosive-service specifier's two questions in one line item: 2.00–3.00% molybdenum for the chlorides — 316's pitting margin, intact — and carbon starved below 0.030% for the welds — 304L's as-welded immunity, kept. That combination made it the default written grade of chemical, pharmaceutical and coastal process plant — very possibly the most-specified stainless flange grade on earth. The construction argument is at its purest: one forging, one closing weld with 316L filler — and nothing for that weld to spoil. The trade is honest — 485/170 MPa against 316's 515/205, nickel widened to 10.0–15.0% — and the ceilings stay stated: chloride SCC above ~60 °C belongs to duplex, the seawater line to the super duplex twins, creep to 316H. A262 testing and pickled-passivated finishes on request. Facings: RF / FF / RTJ. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM A182 F316L · UNS S31603 · W.Nr. 1.4404Both Fixes: Mo for Chlorides + L for WeldsThe Default Written Grade485 / 170 MPa — The Honest TradeNothing for the Weld to SpoilPharma & Hygienic — A262 on RequestB16.5 Flange Ends · Class 150–2500EN 10204 3.1 / 3.2 · ISO 9001:2015
ASTM A182 F316L Long Weld Neck Flanges — Specifications at a Glance
What is an ASTM A182 F316L Long Weld Neck Flange?
Both fixes in one grade, in the nozzle pattern. An ASTM A182 F316L flange (UNS S31603) whose neck continues as a long, heavy-walled straight barrel — the nozzle itself — bevelled for one closing butt weld at the vessel or column shell. Mo 2.00–3.00% for the chlorides; C ≤0.030% for the welds — the L removes carbon, not molybdenum — making this the default written grade of corrosive process plant, welded and left as-welded. The trade is honest: 485/170 MPa against 316's 515/205; Ni widens to 10.0–15.0%. Cryogenic-capable; A262 testing on request. Supplied solution annealed with records. Flange ends per ASME B16.5, Classes 150–2500; barrel length and bore stated by you. EN 10204 3.1 on every lot.
Also searched as: F316L LWN flange, 316L long weld neck flange, S31603 nozzle flange, SS316L LWN, 316L RFLWN, pharma stainless LWN flange — all the same product. Related pages: the facings — LWNRF / LWNFF / LWNRTJ — the long weld neck hub, the F316L socketweld on small bore, its own dial — F316 / F316H — the bench across — F304L — the ladder above — F51 / F53 — and the 316 grade hub / stainless hub.
The Austenitic Bench — Where 316L Completes It
Grade
The Setting
The Mission
Page
F304L
L, no Mo
As-welded duty, clean streams — the cheaper sibling
The rule of the bench: 304L fixes the welds, 316 fixes the chlorides — 316L fixes both, which is why the world's piping classes write it by default.
What Both Fixes Buy Together
Weld Zones That Cannot Sensitise
Below 0.030% carbon there is nothing to precipitate — every joint keeps its film exactly as welded, through the thousand orbital welds of a hygienic system or the one closing weld of this forging.
The Pitting Margin, Kept at Full Strength
The L removes carbon, not molybdenum — PREN stays in the mid-twenties, so the chloride-bearing cleaning cycles, coastal air and brackish utilities that find 304L never get started here.
The Hygienic Industries' Home Grade
Pharma, biotech, food and fine chemicals write 316L by standard — electropolish-friendly, passivation-proven, A262-testable, with the documentation culture to match.
A Weld the Grade Was Born For
The LWN leaves one closing weld per nozzle — and on 316L it can spoil neither the film nor the margin: the construction that deletes joints, in the grade that forgives the one that remains.
Specification Notes — Getting F316L Long Weld Necks Right
Three honest notes.The yield line is real: L-only supply certifies 170 MPa — designs leaning on 205 MPa at moderate heat take dual-certified stock; say which regime your specification follows. Both fixes are not all fixes: chloride SCC above ~60 °C still belongs to duplex, the seawater line to the super duplex twins, and creep to 316H's opposite dial. And check the cheaper sibling: where the stream carries no chlorides, 304L does the as-welded duty without the molybdenum's price.
How Our F316L LWN Flanges Are Manufactured
1
Forging — each piece individually forged from certified low-carbon heats with the barrel integral — no welded build-ups — in any section up to the heaviest HB patterns.
2
Solution annealing — the full-solution cycle and quench that dissolves any carbides and sets the clean austenitic structure; records retained against the heat number.
3
Verification — chemistry per heat with the ≤0.030% carbon certified; mechanicals per heat; A262 intergranular testing arranged where invoked; impacts at MDT for cryogenic work.
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 with the molybdenum line read on every piece; pickled-and-passivated finishes for hygienic work on request; marked with grade, size, schedule and heat number.
6
Certification & packing — EN 10204 3.1 MTC with solution-anneal records (3.2 witnessed on request); L-only or dual 316/316L documentation per the order line; stainless WPS guidance naming 316L fillers; faces and bevels protected, packed sea-worthy.
Where F316L LWN Flanges Are Used
The default grade's world: chemical process vessels and columns, pharmaceutical and biotech plant — tank manways, spray-ball connections, sample points and instrument standpipes — food and beverage systems on chloride-bearing cleaning cycles, coastal and marine-adjacent utilities, water treatment and desalination pre-trains, and cryogenic service riding the low-carbon austenitic toughness to −196 °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
F316L LWN Flange Dimensions
Flange-end dimensions are class-governed per ASME B16.5 (ratings per the low-carbon austenitic group); barrel length and bore per order. Full class-by-class charts:
Seven elements — the documentation regime completes the grade line:
1
Size & standard — e.g. 4″ 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 F316L (L-only) or dual 316/316L, as the specification directs; medium, chloride content, temperature and as-welded status stated — they confirm the rung against 304L across and the duplex ladder above; A262 practice named where invoked; hygienic finishing stated where required; impacts at MDT for cryo.
6
Certification — EN 10204 3.1 with solution-anneal records (our standard) / 3.2 witnessed.
Example: “LWN Flange RF, 4″ NB, ASME B16.5 Class 150, barrel 230 mm, Sch 10S bore, standard pattern, ASTM A182 F316L (L-only), bioreactor manway nozzles — product-contact, pickled & passivated, A262 Practice E on the heat, EN 10204 3.1 — 6 pcs.” Quotations normally within 24 hours with price, unit weight and delivery.
An ASTM A182 F316L long weld neck flange is a forged low-carbon molybdenum austenitic stainless steel flange — UNS S31603, W.Nr. 1.4404 — 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 vessel, column or exchanger shell. F316L carries both of the austenitic bench's fixes in one grade: 2.00-3.00% molybdenum hardens the passive film against chloride pitting, and carbon starved below 0.030% leaves the weld heat-affected zone nothing to precipitate — no sensitisation, no weld decay. That combination has made it the default written grade of corrosive process plant: welded, left as-welded, and trusted. Flange ends follow ASME B16.5 in Classes 150 to 2500; the barrel is machined to the ordered length and bore. Supplied solution annealed with records, ASTM A262 intergranular testing on request.
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 is 316L the default written grade of process plant?
Because it answers the two questions every corrosive-service specifier asks, in one line item. Question one: will the stream's chlorides pit it? The molybdenum answers — PREN in the mid-twenties, the first honest rung above the everyday stainless. Question two: will the welds corrode? The starved carbon answers — below 0.030% the heat-affected zone cannot build a damaging carbide network, so every joint keeps its film exactly as welded, with no post-weld treatment. A grade that needs no caveats on either axis is a grade an engineering office can write by default, and the world's chemical, pharmaceutical and coastal-utility piping classes do exactly that: 316L is very possibly the most-specified stainless flange grade on earth, and its LWN is the corrosion bench's everyday nozzle.
What does the L certificate trade away — and when does it matter?
Strength, honestly stated: 485 MPa tensile and 170 MPa yield against plain 316's 515/205 — carbon is an interstitial strengthener and the L grade has given it up. When it matters follows the 304L page's logic exactly: rarely for class-governed flange geometry, occasionally for code calculations leaning on yield at moderate temperature — which is dual-certified 316/316L stock's territory, meeting the L chemistry and the straight grade's strength at once — and never at the cold end, where the grade's cryogenic career lives. The rule of thumb: where a design genuinely needs 205 MPa on paper, dual-certified supply provides it; where the specification writes 316L for as-welded corrosion duty — the enormous majority — this page is the grade, and the 170 MPa line is the honest price of the weld-zone immunity.
What is the chemical composition of ASTM A182 F316L?
Carbon ≤0.030% — three decimal places of identity — manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%, sulphur ≤0.030%, chromium 16.0-18.0%, nickel 10.0-15.0%, molybdenum 2.00-3.00%. The memorable line: the L removes carbon, not molybdenum — the pitting defence stays at full strength while the weld-zone liability leaves. And as on the 304L page, the nickel range widens (10.0-15.0 against plain 316's 10.0-14.0): carbon is an austenite stabiliser, and with it starved out the specification gives nickel room to hold the phase balance alone. Chemistry is verified per heat, PMI-confirmed with the molybdenum line read, and travels on the EN 10204 3.1 MTC.
What are the mechanical properties of F316L long weld neck flanges?
Solution annealed: tensile strength 485 MPa (70 ksi) minimum, yield strength 170 MPa (25 ksi) minimum, elongation 30% minimum — the deliberately lower certificate that pays for the weld-zone immunity. In nozzle practice the numbers serve comfortably: the class-governed flange end carries the low-carbon group's B16.5 ratings, the heavy barrel's area-replacement work is a geometry calculation the generous wall answers, and the 30% elongation keeps forging, machining and field welding easy. Toughness is the quiet strength — austenite has no brittle transition, and low-carbon austenitics are the cryogenic default to -196°C, with impact testing at minimum design temperature documented where projects require it. Hardness sits low with nothing to manage in supply.
When is L-only supply demanded rather than dual-certified stock?
When the paperwork must prove the corrosion behaviour rather than the strength — the same regimes the 304L page describes, transposed to the molybdenum frame. Dual-certified 316/316L covers most needs, but some specifications write 316L alone deliberately: pharmaceutical and fine-chemical projects qualifying welded systems with ASTM A262 intergranular testing, as-welded chloride duty where the corrosion engineer wants the L allowables used throughout, and projects that forbid dual marking for traceability. In those cases the order line reads F316L, UNS S31603, the certificate documents the L grade on its own terms, and A262 practice testing travels with the lot where invoked — practice letter and condition stated on the order. Both regimes are routine at our works; say which your specification follows.
Why is 316L the pharmaceutical industry's stainless?
Because hygienic engineering multiplies every weld and polishes every surface. Pharmaceutical and biotech plant is orbitally welded by the thousand joints, electropolished, passivated, and cleaned with chloride-bearing agents on validated cycles — a duty profile that demands exactly 316L's two fixes: weld zones that cannot sensitise no matter how many joints the system carries, and a molybdenum film that shrugs off the cleaning chemistry. The industry's hygienic standards are written around the grade, its surface-finish culture assumes it, and its nozzles — tank manways, spray-ball connections, instrument standpipes, sample points — are natural LWN territory where the one-forging construction deletes crevice-prone joints from product-contact systems. Our F316L LWN flanges support that world with pickled-and-passivated finishes on request and the documentation trail hygienic projects expect.
How is the closing weld on an F316L LWN made?
With the friendliest procedure on the site, and with nothing for the weld to spoil — the 304L page's promise, kept on the molybdenum frame. No preheat beyond dryness, no PWHT, ordinary austenitic technique with matching 316L fillers: the heat-affected zone has no carbon to precipitate, so the joint keeps both its film and its pitting margin exactly as welded. The finishing disciplines carry their usual weight — heat tint removed by pickling or passivation on corrosion-critical and hygienic work, since the tinted band is where the molybdenum-bought margin is spent first — and the closing weld at the shell inherits the vessel's own qualified stainless procedure. WPS guidance travels with every supply.
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.
What does 316L NOT fix — the honest ceilings?
The same two walls as its straight-grade parent, stated plainly. Chloride stress corrosion cracking: the low carbon does nothing for the cracking mechanism — under tensile stress in warm chlorides above about 60°C, 316L is as vulnerable as any lean austenitic, and the cure remains the duplex family's ferrite half. The seawater line: PREN in the mid-twenties serves spray, splash and brackish duty, never continuous warm immersion — that franchise starts at 40 with the super duplex twins. And one wall of its own: heat — the starved carbon that protects the welds is precisely what disqualifies the grade from creep service, where the dial swings to 316H's deliberate floor. Welded, corrosive, cold-to-warm: inside that franchise 316L has no rival; outside it, the benches are honest about the hand-off.
When does F316L hand off — across the bench or up the ladder?
Across the bench by chemistry: where the stream carries no chlorides, 304L does the same as-welded duty without the molybdenum's price — the cheaper sibling for nitric acid and clean chemical service. Across by strength: designs leaning on the 205 MPa line take dual-certified stock or the straight grade. Up by temperature: creep service belongs to 316H's carbon floor, the exact opposite dial setting. Up the ladder by chloride arithmetic: when cracking enters the question or the water turns to brine, duplex F51 takes over, and the super duplex twins hold the seawater line; hot reducing acids leave for 904L and the acid bench. The L page's franchise is the widest on the corrosion bench — welded, corrosive, ambient-to-warm, and every hygienic industry on earth — which is exactly why the world writes it by default.
What sizes and pressure classes do F316L 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 F316L order book mirrors its franchise: Classes 150 and 300 dominate — chemical, pharmaceutical and coastal-utility plant rarely needs more — with gas and cryogenic systems reaching for 300-600 and the L-grade group's pressure-temperature ratings governing per B16.5. 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.
What details are needed to get an accurate F316L LWN flange quotation?
Seven elements plus commercial terms: (1) size and dimensional standard — e.g. 4" 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 F316L (L-only) or dual 316/316L, as your specification directs — with the service stated (medium, chloride content, temperature, as-welded status) so the rung is confirmed against 304L across, 316 above and the duplex ladder beyond; A262 practice and condition named where invoked, hygienic finishing (pickling, passivation) stated where required, impacts at MDT for cryogenic work; (7) certification — EN 10204 3.1 with solution-anneal records (our standard) or 3.2 witnessed. Add quantity and destination; quotations normally within 24 hours.
Who manufactures ASTM A182 F316L long weld neck flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing ASTM A182 F316L 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 low-carbon heats, solution annealed with records retained, machined with the barrel bored to the ordered schedule or drawing, bevelled for the closing weld, PMI-checked with the molybdenum line read on every piece, and marked with grade, size, schedule and heat number. Supplied with EN 10204 3.1/3.2 certification, L-only or dual 316/316L documentation as the specification directs, ASTM A262 intergranular testing, cryogenic impacts and pickled-passivated finishes where invoked, and stainless WPS guidance naming 316L fillers — alongside the 316 and 316H rungs of its own dial, the 304 family across the bench, the duplex ladder above, and the complete long weld neck range. Exported to more than 50 countries.
