Tesco Steel & Engineering manufactures ASTM A105 long weld neck flanges — the volume workhorse of the nozzle world: forged carbon steel, UNS K03504, supplied A105 or normalized A105N — with ASME B16.5 flange ends in Classes 150–2500 and the barrel made to order. The construction is the LWN's: the flange and the nozzle in one forging — a long, heavy-walled barrel replacing the pipe nipple and its butt weld, one closing weld made out at the shell — and since most of the world's vessels are carbon steel, most of the world's LWN nozzles are exactly this product. Standard, heavy-barrel and equal-barrel patterns, lengths 150/230/300 mm from stock, bores to schedule, bare, galvanized or epoxy coated (the black-coated barrels pictured below are typical water-treatment supply). The honest boundaries are built in: below −29 °C the certificate hands to A350 LF2; sour duty runs under NACE MR0175 hardness control; the alloy pages cover the exceptions. 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 A105 / A105N · UNS K03504The Nozzle World's Volume Workhorse485 / 250 MPa · 22% ElongationB16.5 Flange Ends · Class 150–2500Barrel: Length & Bore to OrderStandard · Heavy Barrel · Equal BarrelBare · Galvanized · Epoxy CoatedEN 10204 3.1 / 3.2 · ISO 9001:2015
ASTM A105 Long Weld Neck Flanges — Specifications at a Glance
What is an ASTM A105 Long Weld Neck Flange?
The nozzle workhorse in its natural metal. An ASTM A105 forged carbon steel flange (UNS K03504) whose neck continues as a long, heavy-walled straight barrel — the nozzle itself — bevelled for one closing butt weld at the vessel shell or header. It replaces the weld neck + pipe nipple + extra weld of a built-up nozzle: one certificate, one weld to examine, integral metal where reinforcement calculations want it. Flange ends per ASME B16.5, Classes 150–2500; barrel length and bore stated by you; supplied A105 or normalized A105N, bare, galvanized or epoxy coated. Tensile ≥485 MPa, yield ≥250 MPa.EN 10204 3.1 on every lot.
Also searched as: A105 LWN flange, carbon steel long welding neck flange, A105N nozzle flange, MS long weld neck flange, K03504 LWN — all the same product. Related pages: the facings — LWNRF / LWNFF / LWNRTJ — the long weld neck hub, the A105 socketweld cousin on small bore, the carbon steel hub, and the LTCS family below −29 °C.
ASTM A105 LWN Flange Specifications
ASTM A105 Long Weld Neck Flanges are available in the following specifications:
Material Grade
ASTM A105 / A105N forged carbon steel, UNS K03504 — C22.8 / 1.0460 equivalent; certificates carry the designations your documentation uses
Heat Treatment
As-forged, annealed or normalized (A105N) — vessel specifications commonly demand N; condition stated on the MTC
Construction
Integral heavy-walled straight barrel, bevelled weld end (37.5° standard) — one closing butt weld at the shell, no pipe nipple
Flange End
OD, drilling, facing and P-T ratings per ASME B16.5 (Group 1.1); EN 1092-1 drilling to order
Size
1/2"NB to 24"NB per B16.5; larger to order per B16.47 or drawing
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Barrel
Length overall to order — 150 / 230 / 300 mm common stock; bore to pipe schedule ID or special; standard, heavy-barrel (HB) and equal-barrel patterns
Facings
Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ) with groove per B16.20
Finish
Bare with rust-preventive oil (standard); hot-dip galvanized; epoxy / FBE coated — faces and bevels protected
Service Notes
−29 °C floor — LF2 below it; ~425 °C practical ceiling per Group 1.1 tables; NACE MR0175 hardness control where specified
Testing
Chemistry & mechanicals per heat; hardness checked; barrel bore and length gauged piece by piece
Certification
EN 10204 3.1 (standard) / 3.2 witnessed; NACE MR0175, impact tests where specified
Why the Nozzle World Runs on A105 LWNs
The Vessel Is Carbon Steel — So Is the Nozzle
Shells are SA-516 by default, so the nozzle forging is A105 by default: matched chemistry, matched welding, one WPS family across the whole vessel.
Three Parts Become One
The LWN argument at its strongest: weld neck + nipple + one whole butt weld collapse into a single cheap, certified carbon steel forging — and at A105 prices, the one-forging route wins early.
Heavy Barrel = Reinforcement in Forged Form
On Class 900–2500 equipment the HB pattern does the opening's area-replacement work — everyday hardware on separators and drums, forged in any section A105 can supply.
Honest Boundaries, Clearly Signed
Below −29 °C — LF2; above ~425 °C — the chrome-moly grades; corrosive duty — the alloy pages. Between those lines lies most of the process industry, and this page owns it.
Specification Notes — Getting A105 Long Weld Necks Right
Three honest notes.State the heat-treatment condition: plain A105 permits several supply states, but coded vessels and thick LWN sections usually want A105N normalized — if your data sheet is silent, we ask rather than assume. Respect the −29 °C floor: A105 carries no impact requirement — refrigerated and cold-climate design temperatures move the forging to A350 LF2 with Charpy certificates, everything else unchanged. And plan the preheat: LWN barrels are thick sections — B31.3 and ASME VIII call preheat on carbon steel welds above roughly 25 mm, and coded joints may carry PWHT; vessel-shop practice, not pipe-fitter practice.
How Our A105 LWN Flanges Are Manufactured
1
Forging — each piece individually forged from the certified A105 heat with the barrel integral — no welded build-ups — in any section up to the heaviest HB patterns.
2
Heat treatment — normalized (A105N), annealed or as-forged per the order; furnace records retained against the heat number.
3
Machining — flange end to ASME B16.5; barrel turned to pattern (standard / HB / equal) and bored to the ordered schedule or drawing, length gauged face-to-weld-end.
4
Facing & bevelling — RF serrations, flat face or RTJ groove per B16.20; weld end bevelled 37.5° (or per drawing) for the closing butt weld.
5
Testing & marking — chemistry and mechanicals per heat; hardness checked (NACE limits where specified); marked with grade, size, class, schedule and heat number.
6
Finishing & packing — bare-oiled, galvanized or epoxy coated per order with faces and bevels protected; EN 10204 3.1 MTC (3.2 witnessed on request); packed sea-worthy.
Where A105 LWN Flanges Are Used
Everywhere carbon steel holds pressure: pressure-vessel and column nozzles, heat-exchanger channel and shell connections, boiler drum and steam-system nozzles, separator and knock-out drum openings, storage sphere and bullet connections, level-bridle and instrument standpipes, and water-treatment and pipeline hardware — galvanized or epoxy coated where the environment asks. Production and supply below:
Example: “LWN Flange RF, 4″ NB, ASME B16.5 Class 300, barrel 230 mm, Sch 40 bore, heavy barrel, ASTM A105N, EN 10204 3.1 — 12 pcs, exchanger shell nozzles.” Quotations normally within 24 hours with price, unit weight and delivery.
An ASTM A105 long weld neck flange is a forged carbon steel flange — the piping world's volume standard, UNS K03504 — whose neck, instead of tapering to meet a pipe, continues as a long, heavy-walled straight barrel that is itself the nozzle. The flange end carries standard ASME B16.5 dimensions, drilling and facing in Classes 150 to 2500; the barrel runs at constant outside diameter to the ordered length, bored to the ordered schedule, and its far end is bevelled for the single closing butt weld — made out at the vessel shell, exchanger channel or header. In one certified forging it replaces the weld neck flange, the pipe nipple and one whole circumferential weld — and since most of the world's pressure vessels are carbon steel, most of the world's LWN nozzles are exactly this product.
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. Flange-end ratings are shared; everything from the hub outward is a different animal.
Why is A105 the volume workhorse of the nozzle world?
Because the equipment it serves is carbon steel. The great majority of pressure vessels, exchangers, boiler drums, separators and storage spheres are built from carbon steel plate, and their nozzles must match the shell in chemistry and welding behaviour — so the LWN forging is A105 by default, exactly as the shell is SA-516 by default. A105 brings everything the duty asks: 485/250 MPa properties comfortably above the shell plate, forgeability in any barrel section including the heaviest HB patterns, effortless weldability to the shell with standard consumables, a worldwide certification trail, and a price that keeps the one-forging nozzle argument comfortably ahead of the flange-plus-nipple alternative. The alloy pages of this site exist for the exceptions; this page is the rule.
A105 or A105N — what does normalizing buy, and which should be ordered?
Normalizing — the N — is a full austenitising heat treatment followed by still-air cooling that refines and homogenises the forged grain structure. Plain A105 permits several supply conditions depending on size and rating, and for many flanges the as-forged or annealed state serves perfectly well. A105N earns its place where the application cares about toughness and uniformity: pressure-vessel codes and purchaser specifications routinely demand normalized forgings for nozzles, thick sections cool unevenly without it, and impact-tested carbon steel effectively requires it. Long weld necks sit in exactly that territory — heavy sections destined for coded vessels — so most LWN orders sensibly read A105N, and our certificates state the heat-treatment condition either way. If your data sheet says nothing, we will ask rather than assume.
What is the chemical composition of ASTM A105?
Carbon ≤0.35%, manganese 0.60-1.05%, silicon 0.10-0.35%, phosphorus ≤0.035% and sulphur ≤0.040% — with residual caps of copper ≤0.40%, nickel ≤0.40%, chromium ≤0.30%, molybdenum ≤0.12% and vanadium ≤0.08%, plus combined-residual limits in the specification. Read it plainly: this is honest plain carbon steel — the manganese strengthens and manages sulphur, the silicon window (note its floor) marks killed, deoxidised steel, and the residual caps exist to keep stray alloying from disturbing weldability and hardenability, not as deliberate additions. Chemistry is verified per heat and travels on the EN 10204 3.1 MTC; PMI is available where projects demand positive identification even on carbon grades.
What are the mechanical properties of A105 long weld neck flanges?
Tensile strength 485 MPa (70 ksi) minimum, yield strength 250 MPa (36 ksi) minimum, elongation 22% minimum, with a hardness cap of 187 HB in the specification. Two practical readings: the 250 MPa yield comfortably exceeds common shell plate, so the nozzle is never the weak link; and B16.5's pressure-temperature tables for material group 1.1 govern the flange rating from -29°C up to derated service around 425-450°C, where graphitisation caution and the tables themselves retire carbon steel. Below -29°C impact-tested LF2 takes over — its own FAQ below — and above, the chrome-moly grades. Between those honest boundaries lies most of the world's process industry, which is exactly where A105 lives.
When must A105 hand off to A350 LF2?
At -29°C (-20°F), the design-temperature floor below which piping and vessel codes require impact-tested material. A105 carries no Charpy requirement — its toughness at deep cold is real but unproven, and the codes treat unproven as unavailable — while ASTM A350 LF2 is chemically a very close cousin whose certificate includes Charpy V-notch impacts at -46°C. The practical rule for nozzles is simple: refrigerated storage, cryogenic-adjacent service, cold-climate design temperatures or any data sheet stating minus-something beyond -29°C means the LWN forges in LF2, at a modest premium, with everything else on this page unchanged. Our LTCS pages carry that family; state the minimum design temperature on the enquiry and the certificate follows it.
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 are standard, heavy-barrel and equal-barrel LWN flanges?
Three barrel weights for three duties. The standard LWN carries a barrel a little heavier than the matching pipe — the general-purpose vessel nozzle. The heavy-barrel (HB) pattern thickens the wall substantially — often approaching the hub section for its full length — for high-pressure nozzles, heavy nozzle loads and reinforcement-limited openings, where the extra metal does the area-replacement work the code asks of a vessel opening; in carbon steel the HB pattern is everyday hardware on Class 900-2500 equipment. The equal-barrel pattern keeps the barrel outside diameter equal to the hub for a clean cylindrical profile — favoured on manway and instrument connections. All three share B16.5 flange ends; the design calculation or the equipment drawing decides which is wanted.
How is an A105 long weld neck welded to the vessel?
With ordinary carbon steel practice and one heavy-section honesty. The closing joint is a single butt weld between the barrel's bevelled end and the shell or header — standard E7018 or ER70S consumables, full-penetration, volumetrically examinable, which is much of the LWN's appeal: the only weld on the nozzle is a proper one. The honesty is thickness: LWN barrels, and heavy-barrel patterns especially, are thick sections, and B31.3, ASME VIII and most WPSs call preheat on carbon steel above roughly 25 mm — plan the preheat, control the interpass, and thick coded joints may carry PWHT per the governing code. None of this is exotic; it is simply vessel-shop practice rather than pipe-fitter practice, matching where the flange is going. Weld-end bevel comes machined 37.5° unless the drawing says otherwise.
What coatings are available on A105 LWN flanges?
Carbon steel rusts, so the finish belongs on the order. Standard supply is bare metal with rust-preventive oil and protected faces — right for nozzles that will be welded, blasted and painted with the vessel. Beyond that: hot-dip galvanizing for water, utility and atmospheric duty; epoxy and fusion-bonded coatings for buried and marine service — the black epoxy-coated barrels pictured on this page are typical supply for water-treatment and pipeline work; zinc or manganese phosphating as a paint base; and machined faces and bevels are always masked or left bare for welding, whatever the body carries. State the coating system and thickness with the enquiry, and remember the closing weld zone arrives weld-ready, coated after fabrication like the rest of the vessel.
Is A105 acceptable for sour service per NACE MR0175?
Yes — plain carbon steel is one of sour service's standard materials, within the rules. NACE MR0175 / ISO 15156 accepts A105-class forgings for H2S environments subject to hardness control — 22 HRC (237 HB) maximum — and sound welding practice whose procedures keep weld and HAZ hardness within the same limit; A105's specification hardness cap already sits below the threshold, and normalized supply helps uniformity. State the NACE requirement on the enquiry: the certificate then documents hardness testing, and any supplementary requirements your sour spec adds — impact testing, HIC-tested source material for the vessel side, coating exclusions — are handled at order. For sour duty at low temperature, LF2 with the same NACE controls covers both requirements at once.
What sizes and pressure classes do A105 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 — the full class-by-class LWN dimension charts are on this site — with larger diameters forged to order against B16.47 or drawing dimensions, and EN 1092-1 drilling machined on the same barrels. Carbon steel uses the whole spread: Class 150/300 tank and exchanger nozzles by the hundred, Class 600-900 refinery vessels, and Class 1500-2500 heavy-barrel patterns on high-pressure separators and boiler drums. 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 A105 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) material condition and finish — A105 or A105N, bare, galvanized or epoxy coated, with the minimum design temperature stated so the LF2 boundary is respected; (7) certification — EN 10204 3.1 (our standard) or 3.2, NACE MR0175, impact tests where applicable. Add quantity and destination; quotations normally within 24 hours.
Who manufactures ASTM A105 long weld neck flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing ASTM A105 and A105N 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, heat treated with furnace records, machined with the barrel bored to the ordered schedule or drawing, bevelled for the closing weld, hardness checked, and marked with grade, size, class, schedule and heat number. Supplied bare, galvanized or epoxy coated, with EN 10204 3.1/3.2 certification and NACE MR0175 compliance where specified — alongside the LWNRF, LWNFF and LWNRTJ facing pages, the LF2 low-temperature family and the complete flange range. Exported to more than 50 countries.
