Tesco Steel & Engineering manufactures ASTM A182 F304 long weld neck flanges — the world's default stainless: 18-8 austenitic, UNS S30400, W.Nr. 1.4301 — with ASME B16.5 flange ends in Classes 150–2500 and the barrel made to order. The recipe is industry's baseline: chromium 18–20% for the self-healing film, nickel 8–11% for the tough austenite, and no molybdenum — the missing column that prices 304 for the enormous middle of industry: food, beverage, pharma utilities, water, general chemicals. Two credentials the specialist rungs cannot match: dual 304/304L certification as the routine standard of supply, and cryogenic capability to −196 °C — austenite has no brittle transition, where the duplex family stops at −50. The construction is the LWN's: flange and nozzle in one forging, one closing weld at the shell — and the welding is the easiest on the bench: no preheat, no PWHT, ER308L fillers. The limits stay honest: chloride SCC above ~60 °C and salty streams hand off up the ladder — 316, duplex F51, the super duplex twins. Carbon dial: 304L / 304 / 304H. 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 F304 · UNS S30400 · W.Nr. 1.4301The Classic 18-8 — No MolybdenumDual 304/304L Certified — Routine515 / 205 MPa · 30% ElongationCryogenic to −196 °CEasiest Welding on the BenchB16.5 Flange Ends · Class 150–2500EN 10204 3.1 / 3.2 · ISO 9001:2015
ASTM A182 F304 Long Weld Neck Flanges — Specifications at a Glance
What is an ASTM A182 F304 Long Weld Neck Flange?
The everyday stainless, in the nozzle pattern. An ASTM A182 F304 flange (18-8 austenitic, UNS S30400) whose neck continues as a long, heavy-walled straight barrel — the nozzle itself — bevelled for one closing butt weld at the vessel, tank or shell. Cr 18–20% for the film, Ni 8–11% for the austenite, no molybdenum — the world's default stainless, dual 304/304L certified as routine, cryogenic-capable to −196 °C, chloride limits honest (~60 °C SCC ceiling — the ladder climbs from there). C ≤0.08%; Mn ≤2.00%; Si ≤1.00%. 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.
The rule of the bench: the carbon dial tunes 304 for welds or heat; the chloride ladder climbs away from it — and every rung above costs real money, so descending honestly is engineering too.
What the 18-8 Recipe Buys
The Self-Healing Film at the Baseline Price
18–20% chromium rebuilds its own passive film wherever scratched — the whole trick of stainless, priced for tank farms, dairies and water plant by the kilometre.
Dual 304/304L — Sensitisation Answered as Routine
Modern heats certify both grades at once: low carbon that has nothing to precipitate in the weld zone, on the straight grade's 205 MPa certificate that B16.5 ratings assume.
Cryogenic Where Others Stop
No ductile-brittle transition — usable toughness to −196 °C: cold-box and cryo-tank nozzles are natural LWN territory, and the duplex rungs' −50 °C floor never applies.
The Easiest Fabrication on the Bench
No preheat, no PWHT, ER308L fillers, every position — and the one closing weld the LWN leaves is the cheapest weld the corrosion bench knows how to make.
Specification Notes — Getting F304 Long Weld Necks Right
Three honest notes.Respect the chloride walls: pitting finds 304 in salty and crevice-laden service, and SCC starts around 60 °C in warm chlorides — 316's molybdenum is the first answer, duplex the decisive one. Name the dial setting at the extremes: heavy welding on aggressive media → 304L documentation; sustained heat above ~525 °C → 304H — dual-certified stock serves everything between. And descend honestly too: plenty of 316 is specified by habit where 304 serves — across a nozzle schedule the difference is real money.
How Our F304 LWN Flanges Are Manufactured
1
Forging — each piece individually forged from certified 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 carbides and sets the clean austenitic structure; records retained against the heat number.
3
Verification — chemistry and mechanicals per heat; dual 304/304L compliance documented where the heat qualifies; impact testing at minimum design temperature 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 on every piece — the missing molybdenum instantly separates 304 from 316 on the shelf; 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); stainless WPS guidance included; faces and bevels protected, packed sea-worthy.
Where F304 LWN Flanges Are Used
The enormous middle of industry: food and beverage process vessels, dairy and brewery tanks, pharmaceutical utility systems, water and wastewater treatment, general chemical plant, storage-tank nozzles and manways, cryogenic cold boxes and liquid-gas standpipes, and the instrument bridles and level connections that ride on all of them. 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
F304 LWN Flange Dimensions
Flange-end dimensions are class-governed per ASME B16.5 (ratings per the austenitic material group); barrel length and bore per order. Full class-by-class charts:
Seven elements — the medium confirms the rung, the dial setting completes the grade line:
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 F304 (dual 304/304L routine; L-only or H named where the specification requires); medium, chloride content and temperature stated — they confirm 304 against 316 and the duplex ladder; impacts at MDT named for cryogenic duty.
6
Certification — EN 10204 3.1 with solution-anneal records (our standard) / 3.2 witnessed.
An ASTM A182 F304 long weld neck flange is a forged 18-8 austenitic stainless steel flange — UNS S30400, W.Nr. 1.4301 — 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, tank or exchanger shell. F304 is the world's default stainless: chromium 18-20% builds the self-healing passive film, nickel 8-11% holds the tough austenitic structure, and the grade serves everywhere corrosion resistance is wanted without a specialist's enemy to fight — food and beverage plant, pharmaceutical utilities, water, general chemicals, cryogenic liquids. 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, dual 304/304L certified as the modern standard of supply.
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 304 the world's default stainless steel?
Because the 18-8 recipe answers most of industry's corrosion questions at the lowest stainless price. Chromium above 18% forms a chromium-oxide passive film that rebuilds itself wherever it is scratched — the whole trick of stainless steel — and 8-11% nickel stabilises the austenitic structure that brings toughness, formability and the easiest welding in pressure work. What 304 deliberately lacks is molybdenum: the missing column in its chemistry table is its identity, separating it from 316 and pricing it for the enormous middle of industry where the process fluid is water, steam condensate, food, beverage, pharmaceutical product or mild chemistry rather than hot brine. Dairies, breweries, water treatment, utility piping and tank farms are built from it by the kilometre — and their nozzles forge in F304 to match.
What is dual 304/304L certification — and why is it the standard of supply?
Modern melting delivers heats whose carbon sits below 0.030% while their strength still meets straight-grade minimums — so one forging can honestly certify as both 304 (UNS S30400) and 304L (S30403) at once, and dual-marked supply has become the industry's default. The purchaser wins twice: the low carbon answers sensitisation — the old failure mode where welding let chromium carbides form at grain boundaries and locally strip the film — while the certificate keeps the straight grade's 205 MPa yield that B16.5 ratings assume. Practical guidance: a specification naming either grade is satisfied by dual-certified stock; one demanding 304L-only strength allowables (170 MPa yield) should say so. Our certificates state both compliances explicitly where the heat qualifies.
What is the carbon dial — 304L, 304 and 304H?
One chemistry, three carbon settings, three missions — a dial this site follows across the whole austenitic family. 304L caps carbon at 0.030%: the weld-zone insurance setting, immune to sensitisation, traded against a lower certified yield. Straight 304 caps it at 0.08%: the general-purpose setting this page describes, in practice usually supplied dual-certified with L. 304H floors carbon at 0.04% and rides to 0.10%: the creep setting, where deliberately retained carbon builds the carbides that carry strength above roughly 525°C — the same logic the site's Incoloy 800/800H/800HT bench runs at higher temperatures. The dial's rule: name the variant when the service is at an extreme — heavy welding on aggressive media points to L documentation, sustained heat to H — and let dual-certified stock serve everything between.
What is the chemical composition of ASTM A182 F304?
Carbon ≤0.08%, manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%, sulphur ≤0.030%, chromium 18.0-20.0%, nickel 8.0-11.0%. Seven columns, and the eighth's absence is the identity: no molybdenum line — that addition belongs to 316 and prices it accordingly. The chromium does the corrosion work, the nickel buys the austenite, and the carbon cap balances strength against weld-zone behaviour, with modern dual-certified heats sitting below 0.030% anyway. Chemistry is verified per heat, PMI-confirmed — the fastest PMI check on the bench, since the missing molybdenum instantly separates 304 from 316 on the shelf — and travels on the EN 10204 3.1 MTC.
What are the mechanical properties of F304 long weld neck flanges?
Solution annealed: tensile strength 515 MPa (75 ksi) minimum, yield strength 205 MPa (30 ksi) minimum, elongation 30% minimum. The yield is modest beside the duplex rungs' 450-550 — and for flange work that honesty costs little, because B16.5 flange dimensions are class-governed: the geometry is fixed by the pressure class, the austenitic material group's ratings set the pressure-temperature envelope, and the generous 30% elongation pays where it counts, in forgeability, machining and field welding. What the certificate undersells is toughness: austenite keeps its impact strength to cryogenic temperatures, which is the property the next FAQ trades on. Hardness sits comfortably low with no limits to manage in supply.
Can F304 LWN flanges serve cryogenic duty?
Yes — and this is where the austenitic structure outruns every ferritic and duplex rung on the site. Austenite has no ductile-to-brittle transition: 304 keeps usable toughness to -196°C and beyond, which is why liquid nitrogen, liquid oxygen and LNG-adjacent plant is built from austenitic stainless as a matter of course. Compare the neighbours: the duplex family stops near -50°C where its ferrite half turns brittle, and LF2 on the carbon bench certifies -46°C. For LWN work this matters directly — cold-box nozzles, cryogenic storage-tank standpipes, vacuum-jacketed connections and cold-service level bridles are natural long weld neck territory, and the one-forging construction removes a weld from systems where every joint is a potential cold leak. Where a project requires it, impact testing at the minimum design temperature is documented on the certificate.
What are 304's honest chloride limits?
Two walls, both worth stating plainly. Pitting: with no molybdenum, 304's PREN sits in the high teens — fine for potable water, atmosphere and mild chemistry, but salty, briny or poorly-flushed crevice-laden service will find it, and 316's molybdenum is the first answer. Stress corrosion cracking: like all lean austenitics, 304 can crack under tensile stress in warm chlorides, with trouble conventionally starting above about 60°C — the failure mode that the duplex family's ferrite half essentially removes. The ladder on this site runs honestly upward: 316/316L for modest chlorides, duplex F51 where cracking or strength enter the question, the super duplex twins at the seawater line, and the nickel bench beyond. 304 bought for the wrong rung is the cheapest mistake on the ladder to specify and the most expensive to repair — state the medium, chloride content and temperature, and the rung places itself.
How is the closing weld on an F304 LWN made?
Under the friendliest rules in pressure welding — the reason 304 fabrication is priced the way it is. No preheat beyond dryness, no PWHT, no phase-balance arithmetic: matching ER308L-class fillers, ordinary austenitic technique and sensible interpass control produce sound joints in every position. Two disciplines still earn their keep. First, carbon: welding the straight grade can sensitise the heat-affected zone on aggressive duties, which is exactly what dual 304/304L supply answers — the low-carbon heat simply has nothing to precipitate. Second, finishing: on hygienic and corrosion-critical work the weld's heat tint is removed by pickling or passivation, restoring the passive film the service depends on. The closing weld at the shell inherits the vessel's own qualified stainless procedure, and 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.
When does F304 hand off — up the ladder or along the dial?
Three directions, each honest. Up the chloride ladder: when the stream turns salty or warm-and-briny, 316/316L's molybdenum is the first step, duplex F51 the second where cracking resistance or strength join the question, and the super duplex twins hold the seawater line — each rung on this site with its own LWN page. Along the carbon dial: heavy welding on aggressive media points to 304L documentation; sustained service above roughly 525°C points to 304H, whose deliberate carbon carries creep duty. Off the bench entirely: hot reducing acids belong to the nickel-bearing acid ladder, and heat without corrosion to the chrome-moly staircase. The reverse hand-off matters too — plenty of specifications carry 316 out of habit where 304 serves honestly, and the difference is real money across a tank farm's nozzle schedule.
What sizes and pressure classes do F304 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 F304 order book lives where the grade lives: Classes 150 and 300 dominate — food, beverage, pharmaceutical, water and general chemical plant rarely need more — with the higher classes serving gas systems, cryogenic service and the occasional high-pressure utility. 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 F304 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 F304, with dual 304/304L or L-only documentation named where the specification requires it — and the service stated (medium, chloride content, temperature) so the rung is confirmed against 316 and the duplex ladder above, with impact testing at minimum design temperature named 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 F304 long weld neck flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing ASTM A182 F304 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 heats, solution annealed with 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, dual 304/304L documentation where the heat qualifies, impact testing for cryogenic service where specified, and stainless WPS guidance — alongside the 316 rung above, the duplex and super duplex LWN families, and the complete long weld neck range. Exported to more than 50 countries.
