Hastelloy C-276 Long Weld Neck Flanges — UNS N10276 Reducing-Acid LWN Manufacturer
Tesco Steel & Engineering manufactures Hastelloy C-276 long weld neck flanges — the summit of this site's acid ladder: ASTM B564, UNS N10276, W.Nr. 2.4819, NiMo16Cr15W — with ASME B16.5 flange ends in Classes 150–2500 and the barrel made to order. The ladder's logic taken to its end: 15–17% molybdenum with tungsten beside it — the deepest reducing-acid engine on the site — against 625's 8–10% and 825's 2.5–3.5%; chromium deliberately modest; and the weld question's final answer — no stabiliser at all, the impurities simply crushed: carbon to 0.01%, silicon to 0.08% — as-welded service bought at the melt shop. The franchises nothing below holds: hot hydrochloric, wet chlorine and hypochlorite — the enemy the Nickel 200 page named, finally fought — and FGD scrubber chemistry, the alloy's largest habitat. Family and hand-offs stay honest: C-22 sideways for oxidising-heavy duty, B-3 deeper in pure HCl, and every rung below quoted gladly when it genuinely serves — descending honestly is engineering too. One forging, one closing weld with ERNiCrMo-4, as-welded by design. Facings: RF / FF / RTJ; small bore on the C-276 socketweld. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM B564 · UNS N10276 · W.Nr. 2.4819NiMo16Cr15W — The Mo-W EngineC Crushed to 0.01% — As-Welded by DesignHot HCl · Wet Chlorine · FGDThe Acid Ladder's Summit690 / 283 MPa Solution-AnnealedB16.5 Flange Ends · Class 150–2500EN 10204 3.1 / 3.2 · ISO 9001:2015
Hastelloy C-276 Long Weld Neck Flanges — Specifications at a Glance
What is a Hastelloy C-276 Long Weld Neck Flange?
The reducing-acid summit, in the nozzle pattern. A Hastelloy C-276 flange (UNS N10276, ASTM B564) whose neck continues as a long, heavy-walled straight barrel — the nozzle itself — bevelled for one closing butt weld at the reactor, scrubber or column shell. Mo 15–17% + W 3–4.5% — the deepest reducing-acid engine on the site; chromium deliberately modest; carbon crushed to 0.01% for as-welded service. The franchises nothing below holds: hot hydrochloric, wet chlorine, hypochlorite, FGD. Welds with ERNiCrMo-4, no PWHT. Supplied solution-annealed — 690/283/40. Flange ends per ASME B16.5, Classes 150–2500; barrel length and bore stated by you. EN 10204 3.1 on every lot.
The summit — hot HCl, wet chlorine, worst-case mixed acid
This page
The rule at the top: above C-276 there is very little metal left — C-22 sideways where oxidisers dominate, B-3 deeper in pure HCl — and every rung below is quoted gladly when it genuinely serves: descending honestly is engineering too.
What the Summit Recipe Buys
The Deepest Reducing-Acid Engine
15–17% molybdenum with 3–4.5% tungsten beside it — hot hydrochloric across wide concentration and temperature ranges as a named, data-backed duty.
As-Welded, By Purity
Carbon crushed to 0.01%, silicon to 0.08% — no stabiliser needed: heavy fabrication and closing welds serve as-welded in acid that finds any sensitised boundary within weeks.
The Wet-Chlorine Franchise
Wet chlorine, hypochlorite, chlorine dioxide and bleach chemistry — the enemy every dry-halogen page named, finally fought and held.
The FGD Habitat
Flue-gas desulphurisation scrubbers — the alloy's largest single home: hot chlorides, sulphites and swinging pH concentrated into exactly the mixed attack the engine was built for.
Specification Notes — Getting C-276 Long Weld Necks Right
Three honest notes.Name the oxidisers: where nitric, ferric or wet-oxidising chemistry dominates the mix, the C-22 sibling's higher chromium serves better — and pure hot hydrochloric with no oxidisers at all reads the chromium-free B-3. Do not buy the summit for a lower rung's duty: severity without hydrochloric reads 625, sour gas reads 825, named sulphuric reads Alloy 20 — the enquiry that names its chemistry fully is quoted the cheapest rung that genuinely serves. And the alloy-market honesty applies at its fullest: C-276 is among the dearest metals on this site — the lead time is quoted as honestly as the price.
How Our Hastelloy C-276 LWN Flanges Are Manufactured
1
Forging — each piece individually forged from certified N10276 heats kept segregated on the nickel shelf, with the barrel integral — no welded build-ups.
2
Solution-annealing — the alloy's one heat treatment: everything dissolved into the matrix, the corrosion performance set; records retained against the heat number.
3
Verification — chemistry per heat with the crushed carbon and silicon limits certified; mechanicals per heat at the 690/283 line.
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 reads the unmistakable Mo-W signature on every piece — C-276 can mix with nothing else on the shelf; marked with grade, size, schedule and heat number.
6
Certification & packing — EN 10204 3.1 MTC (3.2 witnessed on request); WPS guidance naming the ERNiCrMo-4 filler; faces and bevels protected, packed sea-worthy.
Where Hastelloy C-276 LWN Flanges Are Used
Where the chemistry is at its worst: FGD scrubber systems end to end — absorber vessels, recirculation and spray headers, and their access and instrument nozzles — pulp and paper bleach plants running wet chlorine and hypochlorite, hydrochloric acid production and pickling circuits, chemical reactors on mixed and swinging acid streams, waste incineration and off-gas scrubbing, pharmaceutical duty at glass-lined reactor connections, and the standpipes and level bridles riding on all of them. Modest pressures, unforgiving chemistry, small counts forged to the drawing. One forging, one closing weld. Production and supply below:
Long Weld Necks — Machined at Our WorksLong Weld Neck — Heavy Barrel, Bevelled Weld EndDN600 RF Long Weld Neck — Large Diameter, B16.5 Drilling
Hastelloy C-276 LWN Flange Dimensions
Flange-end dimensions are class-governed per ASME B16.5 (ratings per the alloy's tables); barrel length and bore per order. Full class-by-class charts:
How to Specify & Order a Hastelloy C-276 LWN Flange
Seven elements — the chemistry named fully decides the rung, the sibling or the summit:
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 & chemistry — ASTM B564 Hastelloy C-276 (UNS N10276) — with every acid named (concentration, temperature), oxidisers present or absent, chlorides and their level — checking the C-22 sideways question, the B-3 extreme and the ladder below honestly.
6
Certification — EN 10204 3.1 (our standard) / 3.2 witnessed.
A Hastelloy C-276 long weld neck flange is a forged nickel-molybdenum-chromium-tungsten alloy flange — UNS N10276, W.Nr. 2.4819, NiMo16Cr15W, supplied to ASTM B564 — 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 reactor, scrubber or column shell. C-276 is the summit of this site's acid ladder: 15-17% molybdenum with tungsten as the reducing-acid engine, chromium deliberately modest, and carbon crushed to 0.01% for as-welded service — holding the franchises nothing below reaches: hot hydrochloric, wet chlorine and hypochlorite, FGD chemistry and worst-case mixed acids. 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 690/283 MPa with EN 10204 3.1/3.2 certification.
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.
How is C-276 designed — the molybdenum-tungsten engine and the modest chromium?
As the acid ladder's logic taken to its end. Every rung of the ladder has bought reducing-acid standing with molybdenum: 825 carries 2.5-3.5%, 625 carries 8-10% — and C-276 carries 15-17%, with 3-4.5% tungsten working the same electrochemistry beside it: the deepest reducing-acid engine on this site, the reason hot hydrochloric — the acid that dissolves every rung beneath — is this page's named franchise. The chromium is the design's second lesson: deliberately modest at 14.5-16.5%, enough to stand mixed and mildly oxidising media without diluting the engine — where the C-22 sibling raises it for oxidising-heavy duty, as the family FAQ explains. And nothing at all is spent on hardening or stabilising elements, because the third pillar of the design — the crushed impurity limits of the next FAQ — does that work. Three decisions, one alloy: the metal specified when the chemistry is at its worst and refuses to apologise.
What do the crushed limits mean — the weld question's final answer?
This site has told the weld-decay story across its whole bench: remove the carbon (the L-grades), lock it up (321's titanium, 347's niobium, Alloy 20's columbium, 825's titanium), or embrace it (the H-grades). C-276 is the first answer taken to its logical extreme. Its predecessor — the original Hastelloy C — had the same magnificent acid chemistry but sensitised in the weld zone, forcing post-weld anneals that field fabrication could never deliver. The 1960s fix added no stabiliser at all: melt technology had advanced enough to simply crush the impurities — carbon to 0.01%, silicon to 0.08%, an order tighter than any stainless L-grade — leaving nothing in the metal for a weld cycle to precipitate. The consequence is the alloy's working virtue: heavy fabrication, repair and the closing welds of this page's nozzles all serve as-welded, in acid that finds any sensitised boundary within weeks. No lock, no floor — just purity, bought at the melt shop and certified on every heat.
What is the hydrochloric and wet-chlorine franchise?
The territory at the top of the ladder, held nearly alone. Hot hydrochloric acid is the classic destroyer — the reducing chloride acid that strips chromium films, dissolves stainless at any useful concentration and pushes past every nickel-iron rung — and C-276 serves it across wide concentration and temperature ranges as a named, data-backed duty, with only the chromium-free B-family going deeper in the pure acid. Wet chlorine closes a thread this site opened long ago: the Nickel 200 page's franchise reads dry chlorine, with moist gas named as the enemy — and this page is where that enemy is finally fought: wet chlorine, hypochlorite, chlorine dioxide and bleach chemistry are C-276's home ground, serving pulp bleach plants and chlorination systems. The same chemistry makes flue-gas desulphurisation the alloy's largest single habitat: FGD scrubbers concentrate hot chlorides, sulphites and swinging pH into exactly the mixed attack the Mo-W engine was built for. Pitting and crevice resistance sit beyond every rung beneath, and chloride SCC is off the table at the nickel balance.
What is the chemical composition of Hastelloy C-276 (UNS N10276)?
Nickel the balance (roughly 57%), molybdenum 15.0-17.0%, chromium 14.5-16.5%, iron 4.0-7.0% — a deliberate range, not a cap — tungsten 3.0-4.5%, cobalt ≤2.5%, manganese ≤1.0%, vanadium ≤0.35%, silicon ≤0.08% and carbon ≤0.01% — the two crushed limits that buy as-welded service. Read the design: molybdenum and tungsten are the reducing-acid engine; the chromium is deliberately modest — enough for mixed and mildly oxidising media without diluting the rest; and nothing is spent on hardening or stabilising because the impurity control does that job. Chemistry is verified per heat, PMI-confirmed on every piece — the Mo-W signature is unmistakable on the analyser — and travels on the EN 10204 3.1 MTC.
What are the mechanical properties of Hastelloy C-276 long weld neck flanges?
Solution-annealed to ASTM B564: tensile strength 690 MPa (100 ksi) minimum, yield strength 283 MPa (41 ksi) minimum, elongation 40% minimum — the most ductile certificate on this long weld neck bench at real strength: the heavy molybdenum and tungsten stiffen the solid solution well past ordinary annealed nickel alloys, while the purity keeps the matrix soft enough to absorb every fabrication step. The condition word matters: solution-annealed is the alloy's one heat treatment, dissolving everything into the matrix and setting the corrosion performance the certificates promise — supplied so, with records, and never deliberately aged. The service frame is the wet bench's: the franchises are aqueous, the envelope runs from cryogenic temperatures through hot acid duty, and flange ratings follow B16.5's tables for the alloy with the heavy LWN barrel adding stiffness where nozzle loads bear. At a bolted joint the class system governs, as everywhere on the bench.
What is the ASTM B564 specification for Hastelloy C-276 flanges?
The nickel bench's shared forging standard, at its most severe-service chapter. ASTM B564 (ASME SB-564) spans the family from pure nickel through Monel, the Inconels, the Incoloys and the Hastelloy grades — one standard, many UNS numbers — and its N10276 chapter covers the forged flanges this page describes, solution-annealed condition and all. Around it sit the product-form siblings: B574 for rod, B575 for plate and sheet, B619 and B622 for welded and seamless pipe, all to the same chemistry. Nothing changes at the flange end: dimensions, drilling and facings follow ASME B16.5, with pressure-temperature ratings from the alloy's tables. The order line reads 'ASTM B564 Hastelloy C-276 (UNS N10276)', with the EN designation NiMo16Cr15W / 2.4819 on the same certificate for European drawings — and the alloy-market honesty applies at its fullest here: C-276 is among the dearest metals on this site, and the lead time is quoted as honestly as the price.
What is the C-family — and when do C-22 and B-3 take over?
A bench of siblings, each a deliberate rebalance of the same engine. C-276 is the original and the general answer: the deepest all-round reducing-acid standing with enough chromium for mixed duty. C-22 raises the chromium to roughly 22% at some molybdenum cost — the oxidising-side sibling, preferred where nitric, ferric or wet-oxidising chemistry dominates the mix, and often specified for versatility where a plant's streams swing; its own pages on this site carry the story. C-2000 adds copper for wider sulphuric reach; C-4 simplifies for thermal stability. And beyond the C-family sits the B-family — B-2 and B-3, chromium-free nickel-molybdenum alloys that go deeper still in pure hot hydrochloric, at the price of failing quickly if any oxidiser enters the stream: the specialist's specialist, chosen only when the acid is pure and stays pure. The practical split: mixed and swinging chemistry reads C-276 or C-22 by which side dominates; pure reducing acid reads B-3; and everything milder descends the ladder honestly.
When does C-276 hand off — descending the ladder honestly?
Downward, almost always — because above C-276 there is very little metal left. The summit's premium is real, and every rung below does its own duty for less: 625 where severity stacks but hydrochloric is absent — strength, PREN past 50 and sour standing at a friendlier price; 825 for sour gas and general mixed-acid work; Alloy 20 where the acid is named sulphuric; 904L for wet-chemistry breadth; and the stainless wing below them all for the duties that never needed nickel. Sideways within the family: C-22 where oxidising chemistry dominates, B-3 where pure hot hydrochloric runs without oxidisers, titanium — a different bench entirely — where wet chlorine meets different economics. The site's oldest rule applies hardest at the top: descending honestly is engineering too, and a C-276 enquiry that names its chemistry fully will be quoted the cheapest rung that genuinely serves — which is sometimes, and gladly, this page's.
How is the closing weld on a Hastelloy C-276 LWN made?
As-welded, which is the whole point of the metallurgy. The consumable of record is ERNiCrMo-4 — C-276's own chemistry in wire form — and the crushed carbon means the joint and heat-affected zone carry the parent's acid standing with no post-weld anneal, no stabilising cycle and no sensitisation anxiety: the 1960s redesign exists precisely so that field fabrication in the worst chemistry needs nothing but a good procedure. The care points are the nickel family's, sharpened by the stakes: scrupulous cleanliness — sulphur, paint and grime are punished with cracking; modest heat input with a sluggish pool, favouring the good access the LWN's straight barrel provides; and on multi-pass work, interpass control to keep the wet-service microstructure honest — long exposure in the sensitising band is still avoided as good practice, even though the crushed limits forgive far more than any stainless would. The closing weld inherits the plant's qualified procedure, and 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.
What sizes and pressure classes do Hastelloy C-276 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. The order book mirrors the habitat: FGD scrubbers, bleach plants and chemical reactors concentrate in Classes 150 and 300 — generous connections, modest pressures, the chemistry as the whole load — with pressure-bearing process duty and sour applications reaching higher classes where their piping specifications demand. Piece counts run small and drawings run specific, as befits one of the site's dearest metals: each forging is individually made and certified. State size, class, barrel length and bore together — the four numbers define the forging — with the chemistry named fully, and our quotation returns price, unit weight and delivery per class with the alloy-market lead time quoted honestly.
What details are needed to get an accurate Hastelloy C-276 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 B564 Hastelloy C-276, UNS N10276 — with the chemistry named fully: every acid with concentration and temperature, oxidisers present or absent, chlorides and their level — so the ladder below, the C-22 sideways question and the B-3 extreme are all checked honestly, and the cheapest rung that genuinely serves is the one quoted; (7) certification — EN 10204 3.1 (our standard) or 3.2 witnessed. Add quantity and destination; quotations normally within 24 hours, with the alloy-market lead time quoted honestly.
Who manufactures Hastelloy C-276 long weld neck flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing Hastelloy C-276 long weld neck flanges to ASTM B564 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 N10276 heats kept segregated on the nickel shelf, solution-annealed with records retained, machined with the barrel bored to the ordered schedule or drawing, bevelled for the closing weld, PMI-checked on the unmistakable molybdenum-tungsten signature on every piece, and marked with grade, size, schedule and heat number. Supplied with EN 10204 3.1/3.2 certification and WPS guidance naming the ERNiCrMo-4 filler — alongside the Hastelloy C-276 socketweld, weld neck and blind siblings, the C-22 sibling pages, the whole acid ladder beneath, and the complete long weld neck range. Exported to more than 50 countries.
