Tesco Steel & Engineering manufactures Nickel 201 socketweld flanges — low-carbon pure nickel: ASTM B564, UNS N02201, W.Nr. 2.4068 — to ASME B16.5 from ½″ to 3″ NB in Classes 150–1500. 201 is Nickel 200 with the one internal enemy removed: carbon capped at 0.02%, so there is nothing left to graphitise — and the caustic crown carries from 200's 315 °C ceiling to roughly 600 °C: evaporation to solid, caustic fusion — molten NaOH itself — and the hottest dry chlorine and HCl gas duty. Everything else reads across from the sibling unchanged: the purity franchises, the reducing-only chemistry, the magnetism — and the honest certificate, gentler still at 345/83 MPa, because the carbon that graphitised was also the strengthener. Dual 200/201 certification stated where the heat qualifies. Welded with ERNi-1 filler — no preheat, no PWHT. Facings: SWRF, SWFF, SWRTJ. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
Nickel 201 · B564 · N02201 · 2.4068C ≤0.02% — Nothing Left to GraphitiseThe Caustic Crown to ~600 °CCaustic Fusion — Molten NaOHDual 200/201 Where Heats Qualify345 / 83 MPa · 40% ElongationASME B16.5 ½″–3″ · Class 150–1500EN 10204 3.1 / 3.2 · ISO 9001:2015
Nickel 201 Socketweld Flanges — Specifications at a Glance
What is a Nickel 201 Socketweld Flange?
The hot sibling in the small-bore pattern. A forged low-carbon pure nickel flange (ASTM B564 / UNS N02201 / W.Nr. 2.4068) with a machined socket: pipe seated square by geometry, one external fillet weld with ERNi-1 filler — no preheat, no PWHT — through-bore matched to the pipe schedule. Ni ≥99.0%, C ≤0.02%: nothing left to graphitise, so pure nickel's caustic crown extends from 200's 315 °C limit to ~600 °C — evaporation to solid, caustic fusion, the hottest dry Cl2/HCl gas. Tensile ≥345 MPa, yield ≥83 MPa, elongation ≥40%, annealed. Sized by ASME B16.5 at ½″–3″ NB, Classes 150–1500; EN 10204 3.1 on every lot.
The hot end: final-effect evaporation, caustic fusion, hottest dry gas
This page
One number, one mechanism, one decision: at or below 315 °C either grade serves and 200 is routine; above it, 201 is not an upgrade but a requirement. Dual 200/201 heats satisfy specifications written either way.
What the Missing Carbon Buys
Nothing Left to Graphitise
Above 315 °C, 200's carbon slowly precipitates as grain-boundary graphite, embrittling over years. At 0.02% the mechanism starves — the classic brittle-evaporator failure simply cannot start.
The Crown, Carried Hotter
Final-effect caustic evaporation and molten-NaOH fusion — the single most demanding alkali duty in industry — run on 201 as the standard engineering answer.
Everything Else Reads Across
Purity franchises, colourless chemistry, dry-gas and fluorine service, nobility, magnetism — the 200 page's whole story applies unchanged; only the ceiling moves.
Honesty About the Trade
The removed carbon was also the strengthener: 345/83 MPa — the range's gentlest certificate, managed as always by B16.5's tables and never the reason this grade is bought.
Nickel 201 Chemical Composition (UNS N02201)
Element
Ni
Cu
Fe
Mn
C
Si
S
Weight %
≥99.0
≤0.25
≤0.40
≤0.35
≤0.02
≤0.35
≤0.010
Identical to Nickel 200 except one line: carbon at 0.02% against 200's 0.15% — a factor of seven, and the entire difference between a 315 °C metal and a 600 °C one. PMI confirms purity on every piece; dual 200/201 certification stated where the heat qualifies.
Mechanical Properties (Annealed)
Property
ASTM B564 N02201 Requirement
Tensile Strength
≥ 345 MPa (50 ksi)
Yield Strength (0.2%)
≥ 83 MPa (12 ksi) — gentler even than 200's 103: the removed carbon was the strengthener
Elongation
≥ 40% — the ductility that thermally cycled hot-caustic duty rewards
Condition
Annealed — furnace records certified
Temperature Span
Cryogenic upward to ~600 °C — no graphitisation clock; hot sulphur excluded as for all nickel
Rating
B16.5 nickel-group tables — already reflecting the gentle strength; stated per class on our quotations
One Socket, Three Facings — and the Hot-Gasket Note
Tension & chemistry per heat; PMI on every piece — ≥99% Ni and ≤0.02% C confirmed; socket depth and bore gauged
Certification
EN 10204 3.1 with anneal records (standard) / 3.2 witnessed
Specification Notes — Getting Nickel 201 Sockets Right
Four honest notes.Below 315 °C, don't pay for it:Nickel 200 serves identically at ordinary temperatures with a stronger certificate and better availability — 201 is the hot end's requirement, not a general upgrade. The chemistry still runs reducing or dry: oxidising acids attack pure nickel at any carbon level. Hot sulphur still embrittles: the nickel family's oldest rule applies at 201's temperatures more than anywhere — sulphur-bearing hot gas is excluded, and our shop keeps sulphur off the metal down to the marking crayons. And the certificate is gentle: 345/83 MPa — B16.5's tables manage it, but where mechanical abuse is on the menu, say so on the enquiry.
How Our Nickel 201 Socketweld Flanges Are Manufactured
1
Forging — cut billet of the spectro-verified low-carbon N02201 heat is hot-forged into the flange blank with full heat traceability and segregated nickel handling.
2
Annealing — sets the soft, fully ductile structure; furnace charts retained against the heat number.
3
Machining — faces, OD and drilling to ASME B16.5 on dedicated stations with sulphur-free lubricants — low-carbon nickel is the family's gummiest metal: sharp tooling, positive feeds; socket counterbore and depth gauged piece by piece, through-bore matched to the ordered schedule.
4
Facing — RF serrations, flat face or RTJ groove per B16.20.
5
Testing & marking — tension and chemistry per heat; PMI on every piece with purity and carbon confirmed; laser-marked with grade, size, class, schedule and heat number.
6
Certification & packing — EN 10204 3.1 MTC with anneal records, dual 200/201 stated where the heat qualifies (3.2 witnessed on request); ERNi-1 WPS guidance included; packed sea-worthy with no carbon-steel contact.
Where Nickel 201 Socketweld Flanges Are Used
The hot end of the pure-nickel world: caustic evaporation final effects taking 50% liquor toward solid, caustic fusion and molten-NaOH handling, the hottest stretches of chlor-alkali, viscose rayon and alumina plants, hot dry chlorine and hydrogen chloride gas systems, and fluorine service at temperature. Production below:
How to Specify & Order a Nickel 201 Socketweld Flange
Six elements — led by the number that chose the grade:
1
Design temperature — it justifies 201 over 200 and sets the gasket guidance; we ask if it is missing.
2
Size & standard — e.g. 1″ NB ASME B16.5, or DN25 EN 1092-1 to order.
3
Pressure class & facing — 150#–1500#; SWRF (the default), SWFF or SWRTJ with ring number.
4
Pipe schedule & grade line — the through-bore matches the pipe ID; Nickel 201 / B564 N02201 / 2.4068 all name the same metal, dual 200/201 where the heat qualifies.
5
Certification — EN 10204 3.1 with anneal records (our standard) / 3.2 witnessed, PMI as applicable.
A Nickel 201 socketweld flange is a forged low-carbon commercially pure nickel flange — at least 99% nickel with carbon capped at 0.02%, ASTM B564, UNS N02201, W.Nr. 2.4068 — whose back carries a machined socket: the pipe end seats inside, self-aligned square to the face, and is secured with a single external fillet weld. 201 is Nickel 200 with the one internal enemy removed: with almost no carbon there is nothing to precipitate as graphite at high temperature, so the metal keeps pure nickel's caustic crown and carries it to roughly 600°C — the hot half of the territory, where 200's 315°C limit bites. Dimensioned to ASME B16.5 for ½" to 3" NB in Classes 150 to 1500 — the hot sibling, in the small-bore pattern.
Why does removing carbon unlock the hot end?
Because in pure nickel above roughly 315°C, carbon is a slow saboteur. Nickel dissolves very little carbon at service temperatures, so whatever the metal carries eventually comes out of solution — and it comes out as graphite, precipitating along the grain boundaries over months and years of hot service. Each graphite film is a plane of weakness; the accumulating network embrittles the metal from within, and the classic casualty is a caustic evaporator component gone brittle after years of faithful duty. There is no alloying cure — carbon must simply not be there. Nickel 201's 0.02% ceiling starves the mechanism completely: nothing to precipitate, nothing to embrittle, and the ceiling lifts from 315°C to roughly 600°C, where other limits of pure nickel take over. One number, one mechanism, one grade.
What is the chemical composition of Nickel 201 (UNS N02201)?
Nickel 99.0% minimum, carbon ≤0.02% — and the rest are the same trace ceilings as Nickel 200: copper ≤0.25%, iron ≤0.40%, manganese ≤0.35%, silicon ≤0.35%, sulphur ≤0.010%. Set beside its sibling, the specification is identical except for one line: 200 allows carbon to 0.15%, 201 caps it at 0.02% — a factor of seven, and the entire difference between a 315°C metal and a 600°C one. The sulphur ceiling matters as much here as anywhere in the nickel family, guarding hot workability and weldability. Chemistry is verified per heat and travels on the EN 10204 3.1 MTC — and where a heat qualifies for both grades, dual 200/201 certification is stated, satisfying specifications written either way.
What are the mechanical properties of Nickel 201 socketweld flanges?
In the annealed condition ASTM B564 requires tensile strength 345 MPa (50 ksi) minimum, yield strength 83 MPa (12 ksi) minimum and elongation 40% minimum — gentler even than Nickel 200's 380/103, because the removed carbon was also the metal's modest strengthener. This is the softest certificate in our entire socketweld range, and the honest framing is the same as the sibling's: pure nickel is bought for chemistry, and B16.5's nickel-group pressure-temperature tables already reflect the gentle numbers, so a properly classed 201 flange carries its rated duty with normal margins. The enormous ductility is an asset in the thermally cycled hot-caustic service that is this grade's home. Strength shoppers left this neighbourhood several pages ago.
Nickel 201 or 200 — which do I order?
Temperature decides, exactly as the 200 page says from the other side. At or below 315°C, either grade serves: 200 is the routine supply, slightly stronger and more available, and there is no reason to pay 201's premium. Above 315°C — and hot caustic duty lives exactly there — 201 is not an upgrade but a requirement: 200's carbon will graphitise and embrittle over service life, and no certificate wording rescues it. The practical answers: state the design temperature on every pure-nickel enquiry (we ask if it is missing); write 201 by name for the hot end; and where mill heats qualify for both, dual 200/201 certification covers specifications written either way. The two pages of this sibling pair link each other for exactly this decision.
What does Nickel 201 serve above 315°C?
The hottest duties in pure nickel's franchise. Caustic evaporation's final effects, where 50% liquor is taken toward anhydrous solid and metal temperatures climb well past the sibling's limit; caustic fusion itself — molten NaOH handling, the single most demanding alkali duty in industry; the hot ends of chlor-alkali, viscose rayon and alumina plants; and the gas side at its hottest — dry chlorine and dry hydrogen chloride, where nickel's protective chloride film serves to several hundred degrees and 201's freedom from graphitisation lets the metal actually go there. The upper boundary, around 600°C, is set by pure nickel's own oxidation and strength limits rather than by any internal clock — and hot sulphur remains excluded, as everywhere in the nickel family.
Does 201 keep the rest of pure nickel's behaviour?
Entirely — carbon aside, it is the same metal. The caustic crown chemistry, the colourless non-staining corrosion products that protect rayon and food-grade purity, the dry-gas and fluorine franchises, the nobility principle shared with Monel, and the ferromagnetism — a 201 flange sticks to a magnet just as a 200 does, and the same do-not-reject warning applies. The weaknesses carry over too: oxidising acids attack the bare metal, hot sulphur embrittles it, and the strength is gentle. Our Nickel 200 page tells the full story of all of these; this page's job is the one thing 201 changes — the temperature ceiling — and everything else can be read across without adjustment.
How is a Nickel 201 socketweld flange welded?
Identically to its sibling, with the nickel family's cleanliness religion. Geometry is standard: pipe bottomed in the socket, withdrawn 1/16" (1.6 mm) to leave the expansion gap, single external fillet weld — with ERNi-1, the pure-nickel filler that serves both grades; its own low carbon suits 201's logic. No preheat, no PWHT. Contamination control is the discipline: sulphur, lead and zinc embrittle hot nickel, so joints are degreased, marking materials checked and tooling dedicated — doubly relevant here, since 201 weldments are headed for the hot service where sulphur damage expresses itself. Weld metal is sluggish; wider bevels and unhurried technique are normal. Our flanges arrive annealed with records, and WPS guidance travels with every supply.
What facings are Nickel 201 socketweld flanges made with?
All three, each with its own page on this site: raised face (SWRF) — the default — flat face (SWFF) for GRP, lined and cast equipment mates, and ring type joint (SWRTJ) for the rare high-pressure case, with soft iron or nickel rings per the duty. The gasket question is sharper here than on the 200 page because the service is hotter: PTFE is long gone at 201's working temperatures — graphite carries the middle of the range, and the hottest caustic and fusion-adjacent joints move to specialised metallic and mica systems selected for the actual joint temperature. State it on the enquiry and the sealing recommendation rides with the quotation. NPT-tapped variants are machined and certified at the works.
What sizes and pressure classes do Nickel 201 socketweld flanges come in?
ASME B16.5 standardises socket weld flanges from ½" to 3" NB in Classes 150, 300, 600, 900 and 1500 — Class 900 sharing Class 1500 dimensions in most small-bore sizes — with 4" and Class 2500 made to order. Hot caustic and fusion small bore lives almost entirely in Classes 150 and 300, at modest pressures where the chemistry and the temperature, not the rating, drive the specification. Put the pipe schedule on the enquiry — the through-bore is matched to the pipe ID — and state the design temperature, which both confirms the grade choice and sets the applicable B16.5 rating; our quotations state it per class.
What details are needed to get an accurate Nickel 201 socketweld flange quotation?
Six elements, led by the number that chose the grade: (1) the design temperature — it justifies 201 over 200 and sets the gasket guidance; (2) size — ½" to 3" NB; (3) pressure class — 150 to 1500, with facing (SWRF, SWFF or SWRTJ) and ring number where applicable; (4) the pipe schedule, so the through-bore matches the pipe ID; (5) the grade line — Nickel 201, ASTM B564, UNS N02201 or W.Nr. 2.4068 all name the same metal, with dual 200/201 certification available where the heat qualifies; (6) certification — EN 10204 3.1 with anneal records (our standard) or 3.2 witnessed, PMI as applicable. Add the caustic concentration alongside the temperature, plus quantity and destination. Quotations normally within 24 hours.
Is Nickel 201 stocked or made to order?
Scarcer than its sibling, quoted just as quickly. The market splits the pure-nickel family's volume toward 200, so dedicated 201 flange stock is thin everywhere — but the practical picture is better than that sounds: modern mill heats are often melted lean enough to dual-certify as 200/201, and our nickel stock is selected with that in mind, so much of what serves a 200 enquiry can certify for a 201 line too. Where a single-certified 201 heat is required, forging to order runs days to a few weeks by quantity. Caustic-plant shutdowns are a duty we know — say so on the enquiry and small lots can usually be expedited, with the EN 10204 3.1 certificate carrying the 2.4068 designation where European documentation expects it.
Who manufactures Nickel 201 socketweld flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing Nickel 201 (ASTM B564, UNS N02201) socket weld flanges from ½" to 3" NB (larger to order) in Classes 150-1500 — each forged from certified low-carbon heats, annealed with furnace records against the heat number, machined on dedicated nickel-alloy stations with sulphur-free lubricants, gauged socket depth and schedule-matched bore, PMI-checked — the ≥99% nickel and ≤0.02% carbon confirmed on every piece — and laser-marked with grade, size, class, schedule and heat number. Supplied with EN 10204 3.1/3.2 certification — dual 200/201 stated where the heat qualifies — alongside the Nickel 200 sibling, the Monel family and the full nickel-alloy socketweld range this series covers. Exported to more than 50 countries.
