Tesco Steel & Engineering manufactures Incoloy 800H socketweld flanges — the creep certificate: ASTM B564, UNS N08810, W.Nr. 1.4958 — to ASME B16.5 from ½″ to 3″ NB in Classes 150–1500. 800H is plain Alloy 800 re-certified for the hot side of 593 °C: carbon given a floor — 0.05–0.10% — and the grain deliberately coarsened by a high solution anneal, because grain boundaries are where creep happens. The trade is printed honestly on the datasheet — 450/170 MPa at room temperature against 800's 520/205 — and repaid in stress-rupture life at the reformer. This is the carbon dial the stainless bench knows from 304H, turned on the Incoloy bench. Above it, 800HT takes the hottest duty; below 593 °C, plain 800 is better and cheaper; the Inconels — 600 and 601 — wait beyond. Welded with ERNiCr-3 or 617-type 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.
Incoloy 800H · B564 · N08810 · 1.4958C 0.05–0.10% — A Floor and a CapCoarse Grain — Built Against CreepThe Certificate for 593–760 °C450 / 170 MPa — The Honest TradeReformer & Ethylene CountryASME B16.5 ½″–3″ · Class 150–1500EN 10204 3.1 / 3.2 · ISO 9001:2015
Incoloy 800H Socketweld Flanges — Specifications at a Glance
What is an Incoloy 800H Socketweld Flange?
The creep certificate in the small-bore pattern. A forged Incoloy 800H flange (ASTM B564 / UNS N08810 / W.Nr. 1.4958) with a machined socket: pipe seated square by geometry, one external fillet weld — no preheat, no PWHT — through-bore matched to the pipe schedule. Plain 800's chemistry with carbon held at 0.05–0.10% — a guaranteed floor — and a high solution anneal that coarsens the grain: carbides pin the structure, fewer boundaries creep slower, and the alloy holds together past 593 °C toward 760 °C where plain 800's certificate retires. Tensile ≥450 MPa, yield ≥170 MPa, elongation ≥30% — deliberately below 800's, repaid in rupture life. Sized by ASME B16.5 at ½″–3″ NB, Classes 150–1500; EN 10204 3.1 with grain-size records on every lot.
Also searched as: Alloy 800H socket weld flange, N08810 SW flange, 1.4958 socket weld flange, controlled-carbon 800 flange, X5NiCrAlTi31-20 flange — all the same product family. Related pages: the facings — SWRF / SWFF / SWRTJ — the socketweld hub, the other Incoloy 800H types — blind, weld neck, slip-on — the siblings 800 / 800HT / 825 socketweld, and the stainless creep grade F304H below it.
The same dial the stainless bench turns from 304L through 304 to 304H — carbon down for corrosion, carbon up (and guaranteed) for creep. The three UNS numbers are separate certificates and are not substitutable.
What the Carbon Floor and the Coarse Grain Buy
The Carbon Floor
0.05–0.10% guaranteed — enough carbon, certified, to form the carbides that pin grain boundaries against slow deformation. Plain 800's ≤0.10% cap could legally arrive at 0.01% — useless for creep.
The Coarse Grain
Creep lives on grain boundaries — atoms diffuse along them, grains slide past them. The high solution anneal cuts boundary area per volume, which is why the certificate records grain size, typically ASTM No. 5 or coarser.
The Reformer Career
Steam reformers, ethylene furnaces, convection-section steam — the 593–760 °C world runs on this certificate: nickel enough for stability and carburising gas, iron enough for the price, creep strength certified by code.
Honesty About the Cold Side
Below 593 °C the coarse grain buys nothing and the certificate reads weaker — plain 800 is better and cheaper there. Order by design temperature, not by prestige.
Incoloy 800H Chemical Composition (UNS N08810)
Element
Ni
Cr
Fe
C
Al
Ti
Mn
Si
Cu
S
Weight %
30.0–35.0
19.0–23.0
≥39.5
0.05–0.10
0.15–0.60
0.15–0.60
≤1.50
≤1.0
≤0.75
≤0.015
The carbon window is the identity — read it against plain 800's simple ≤0.10% cap and 800HT's 0.06–0.10% with Al+Ti tightened to 0.85–1.20%. The iron floor and the mid-band nickel carry over from the family recipe. Grain size travels on the certificate alongside the chemistry. PMI confirms every piece.
Mechanical Properties (Solution Annealed)
Property
ASTM B564 N08810 Requirement
Tensile Strength
≥ 450 MPa (65 ksi) — deliberately below plain 800's 520: the coarse grain trades ambient strength for rupture life
Yield Strength (0.2%)
≥ 170 MPa (25 ksi)
Elongation
≥ 30% — fully austenitic, no ductile-brittle transition
Condition
Solution Annealed, coarse grain — furnace charts and grain-size records certified
Temperature Span
The certificate for 593–760 °C creep-governed service; oxidation scale sound to ~800 °C; below 593 °C plain 800 serves better
Rating
B16.5 nickel-alloy tables govern the joint — gasket-limited before metal-limited; stated per class on our quotations
One Socket, Three Facings — and the Hot-Joint Note
At creep-range temperatures the joint's design problem is the sealing system and the bolting — standard studs creep long before an 800H flange notices. State the actual joint temperature; sealing and bolting guidance ride with the quotation.
Incoloy 800H Socketweld Flange Specifications
Incoloy 800H Socketweld Flanges are available in the following specifications:
Material Grade
Incoloy 800H, ASTM B564 (UNS N08810), W.Nr. 1.4958 — dual-certified 800H/800HT material supplied where documentation accepts it
Heat Treatment
Solution annealed, coarse grain (typically ASTM No. 5 or coarser) — furnace charts and grain-size records certified
Size
1/2"NB to 3"NB per ASME B16.5; 4″ and larger to order; EN 1092-1 patterns to order
Class
150#, 300#, 600#, 900#, 1500# (900# shares 1500# dimensions in most sizes) — creep-range trim lives mostly in 150/300
Facings
Raised Face (SWRF), Flat Face (SWFF), Ring Type Joint (SWRTJ) with groove per B16.20
Bore
Socket bore to pipe OD; through-bore matched to pipe schedule
Welding
Single external fillet with 1/16″ expansion gap; ERNiCr-3 filler (617-type for the hottest joints); sulphur-clean practice; no preheat, no PWHT
Service Span
Creep-governed duty 593–760 °C — reformer, ethylene and furnace-adjacent small bore; below 593 °C use plain 800; halogens and caustic to 600; acids to 825 — see the notes
Tension & chemistry per heat; PMI on every piece; grain size verified; socket depth and bore gauged
Certification
EN 10204 3.1 with solution-anneal and grain-size records (standard) / 3.2 witnessed
Specification Notes — Getting Alloy 800H Sockets Right
Four honest notes.Below 593 °C it gives strength away for nothing: the cold side belongs to plain 800 — better certificate, better price; do not upgrade for prestige. The family's chemistry limits carry over: halogens and caustic stay with 600, the aggressive acid bench with 825 and Alloy 20. Sensitisation honesty: the deliberate carbon that serves creep can precipitate at boundaries over long hot service — aqueous duty after hot service deserves case-by-case review. And the certificates are not substitutable: N08800, N08810 and N08811 are three different specifications — a flange certified 800 cannot stand in for 800H in a creep line, in either direction of convenience.
How Our Incoloy 800H Socketweld Flanges Are Manufactured
1
Forging — cut billet of the spectro-verified N08810 controlled-carbon heat is hot-forged into the flange blank with full heat traceability and segregated nickel-alloy handling.
2
Solution annealing — the high anneal sets the coarse grain the creep certificate is built on; furnace charts and grain-size measurements retained against the heat number.
3
Machining — faces, OD and drilling to ASME B16.5 on dedicated stations with sulphur-free lubricants; 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 and grain-size verification; laser-marked with grade, size, class, schedule and heat number.
6
Certification & packing — EN 10204 3.1 MTC with solution-anneal and grain-size records (3.2 witnessed on request); WPS guidance included; packed sea-worthy with no carbon-steel contact.
Where Incoloy 800H Socketweld Flanges Are Used
In the creep band, 593–760 °C: steam-reformer plant small bore — convection-section steam, collector- and header-adjacent connections — ethylene and pyrolysis furnace trim, heat-treatment and carburising furnace hardware, hot-gas ducting instrumentation, and power and petrochemical steam systems running hot enough for code creep rules. Production below:
Socket weld flange dimensions are class-governed per ASME B16.5 — identical across material grades (pressure-temperature ratings follow the nickel-alloy group). Full charts:
How to Specify & Order an Incoloy 800H Socketweld Flange
Six elements — the design temperature picks the certificate:
1
Size & standard — e.g. 1″ NB ASME B16.5, or DN25 EN 1092-1 to order.
2
Pressure class & facing — 150#–1500#; SWRF (the default), SWFF or SWRTJ — with the design and joint temperatures, which govern the rating, the sealing guidance and the grade itself.
3
Pipe schedule — the through-bore is matched to the pipe ID.
4
Grade line — Incoloy 800H / B564 / N08810 / 1.4958; note whether dual-certified 800H/800HT is acceptable — it simplifies supply; if the line runs cooler than 593 °C, plain 800 is the better order.
5
Certification — EN 10204 3.1 with solution-anneal and grain-size records (our standard) / 3.2 witnessed, PMI as applicable.
An Incoloy 800H socketweld flange is a forged controlled-carbon iron-nickel-chromium alloy flange — 30-35% nickel and 19-23% chromium on an iron base of at least 39.5%, with carbon held in a deliberate 0.05-0.10% window, ASTM B564, UNS N08810, W.Nr. 1.4958 — 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. 800H is plain Alloy 800 re-certified for the hot side of 593°C: the carbon floor and a high solution anneal that coarsens the grain give it the stress-rupture strength that code creep service demands — the reformer-country grade of the Incoloy bench. Dimensioned to ASME B16.5 for ½" to 3" NB in Classes 150 to 1500.
What makes 800H different from plain Incoloy 800?
Two deliberate changes to the same chemistry, both aimed at creep. First, carbon gets a floor: plain 800 allows anything up to 0.10%, while 800H demands 0.05-0.10% — enough carbon, guaranteed, to form the carbides that pin the structure against slow deformation at temperature. Second, the heat treatment changes: 800H is solution-annealed high enough to coarsen the grain deliberately, because grain boundaries are where creep happens — fewer boundaries per volume means slower creep. Everything else — the nickel, the chromium, the iron floor, the small aluminium and titanium — carries over from the 800 page. The result is a separate UNS number (N08810), a separate W.Nr. (1.4958), a separate certificate, and a different job: 800 below 593°C, 800H above it.
Why is 800H's certificate weaker than plain 800's at room temperature?
Because the datasheet is honest about the trade. ASTM B564 requires 450 MPa tensile and 170 MPa yield from 800H against 520/205 from plain 800 — the coarse grain that resists creep at 700°C is simply softer at 20°C, and fine grain, which strengthens metals at room temperature, is exactly what you do not want at the reformer. Nothing has gone wrong: the certificate numbers fall because the microstructure has been re-optimised for a different enemy. This is why grade substitution runs both ways here — an 800H flange in a cold line gives away strength for nothing, and an 800 flange in a creep line lacks the certified microstructure the code assumes. Order by design temperature, not by which certificate reads stronger.
What is the chemical composition of Incoloy 800H (UNS N08810)?
Nickel 30.0-35.0%, chromium 19.0-23.0%, iron ≥39.5% — the family's deliberate iron floor — carbon 0.05-0.10% as both floor and cap, aluminium 0.15-0.60% and titanium 0.15-0.60%, manganese ≤1.50%, silicon ≤1.0%, copper ≤0.75%, sulphur ≤0.015%. The carbon window is the identity: read it against plain 800's simple ≤0.10% cap and 800HT's 0.06-0.10% with its tightened aluminium-plus-titanium requirement of 0.85-1.20%. Grain size is part of the specification in practice — coarse, typically ASTM No. 5 or coarser, set by the solution anneal and recorded on the certificate. Chemistry is verified per heat, PMI-confirmed on every piece, and travels on the EN 10204 3.1 MTC.
What are the mechanical properties of Incoloy 800H socketweld flanges?
In the solution-annealed condition ASTM B564 requires tensile strength 450 MPa (65 ksi) minimum, yield strength 170 MPa (25 ksi) minimum and elongation 30% minimum. The room-temperature certificate deliberately reads below plain 800's — the coarse grain trades ambient strength for what actually matters above 593°C: stress-rupture and creep strength over tens of thousands of hours, which is the property ASME's creep-governed allowable stresses are built on. The structure stays fully austenitic and tough, the solution anneal and grain size travel on the certificate, and B16.5's nickel-alloy pressure-temperature tables govern the flange rating — with the gasket and bolting retiring the bolted joint long before the metal, the two-ceilings honesty of every hot page here.
What is creep, and why does coarse grain resist it?
Creep is slow, permanent deformation under stress at high temperature — a pipe flange that is perfectly safe by ordinary strength rules can still stretch, sag and eventually rupture over years at 700°C. It happens mostly at grain boundaries: atoms diffuse along them and grains slide past one another, so the more boundary area a microstructure has, the faster it creeps. That inverts the usual metallurgy: fine grain, prized at room temperature, becomes a liability at the reformer. 800H attacks creep from both sides — the high solution anneal coarsens the grain, cutting boundary area, and the guaranteed 0.05-0.10% carbon forms carbides that pin the boundaries that remain. This is also why the code switches from tensile-based to creep-based allowable stresses above roughly 593°C, and why the H certificate exists at all.
Incoloy 800H or 800HT — which creep grade?
800HT is the same idea taken one step further: carbon tightened to 0.06-0.10% and the aluminium-plus-titanium sum controlled at 0.85-1.20%, buying additional creep and stress-rupture strength for the hottest duty, toward 760°C and beyond. 800H covers the great bulk of creep-range service and is the more commonly stocked certificate; 800HT earns its place at the top of the family's temperature range and wherever a specification names N08811. A practical note from the mill world: much modern material is dual-certified 800H/800HT, meeting both windows at once — if your documentation accepts either, say so on the enquiry and supply is simpler; if it names one, the certificate follows exactly. Both grades have their own pages here, and plain 800 remains the right answer below 593°C.
How hot can Incoloy 800H actually go?
The certificate is built for the band above 593°C and serves toward 760°C in creep-governed code service, with oxidation resistance — the same 19-23% chromium scale as the rest of the family — sound to roughly 800°C and excursions above. Above the family's range, the duty passes to the Inconels: 600 for the broad hot range and halogens, 601 for the cycled summit toward 1200°C. The joint tells its own story, as everywhere in this series: B16.5's tables and the gasket system govern a bolted connection far below the metal's ceiling, so 800H socket weld flanges live on reformer- and furnace-adjacent small bore — convection-section steam, hot collectors, purge and instrument connections — where the pipe demands the creep certificate and the joint sits within the flange envelope. State both temperatures on the enquiry.
Incoloy 800H or the stainless creep grades — 304H and 321H?
The carbon dial is the same trick on both benches — 304H and 321H hold carbon windows for exactly the same creep-strength reason, and below roughly 650°C in clean steady service they do the job at stainless prices; our 304H page tells that story from the stainless side. 800H earns the upgrade three ways: temperature — its useful creep range runs deeper, toward 760°C, where the stainless H-grades are running out; stability — 30-35% nickel holds its austenite without the sigma-phase embrittlement that stalks high-chromium stainless through long hot dwells; and atmosphere — chloride SCC immunity and carburisation resistance come with the nickel, which no stainless H-grade can offer. The honest rule: clean steady creep duty at moderate temperature — stainless H-grades on price; deeper heat, carburising gas, chlorides or decades-long dwell — 800H.
Incoloy 800H or the Inconels?
By what the duty pays for. 800H's franchise is certified creep strength in the 593-760°C band at an iron-floor price — the steam-reformer and ethylene world runs on it. Inconel 600 costs more and offers no creep certificate advantage in that band; what it buys instead is chemistry — the hot halogen and caustic franchises — and headroom toward 1095°C. Inconel 601 buys the cycled summit toward 1200°C with its clinging alumina scale. So the split writes itself: creep-governed structural duty in reformer country — 800H, and its price advantage is decisive at volume; halogens, caustic or the last 300 degrees — the Inconel pages. The families meet in many plants, and the design temperature plus the atmosphere — not the brand names — should pick the grade.
What are Incoloy 800H's honest weaknesses?
Four, named plainly. The cold-side giveaway: below 593°C the coarse grain buys nothing and the certificate reads weaker — plain 800 is better and cheaper there; do not upgrade for prestige. The chemistry limits it shares with its family: 30-35% nickel is not the halogen-and-caustic ≥72% — that stays with 600 — and with no molybdenum the aggressive wet-acid bench belongs to 825 and beyond. Sensitisation honesty: the deliberate carbon that serves creep can precipitate at grain boundaries through long service, so aqueous-corrosion duty after hot service deserves review — a certificate question we answer case by case. And hot reducing sulphur attacks the nickel matrix as everywhere, moderated but not erased by the high iron. None of these touch the reformer franchise it was certified for.
How is an Incoloy 800H socketweld flange welded?
With nickel-family practice and one creep-specific discipline. Geometry is standard: pipe bottomed in the socket, withdrawn 1/16" (1.6 mm) to leave the expansion gap, single external fillet weld — no preheat, no PWHT. Filler follows service temperature: ERNiCr-3 is the workhorse for joints operating into the lower creep range, and 617-type consumables serve the hottest 800H fabrication, keeping deposit creep strength honest against the base metal — a real consideration on a certificate bought specifically for stress-rupture life. Sulphur-clean housekeeping is non-negotiable, doubly so for weldments headed above 600°C: sulphur-free lubricants, dedicated brushes, no carbon-steel contact. Our flanges arrive solution-annealed with grain-size records, and WPS guidance travels with every supply.
What sizes and pressure classes do Incoloy 800H 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. Creep-range small bore lives mostly in Classes 150 and 300 — convection-section steam trim, purge, instrument and collector-adjacent connections where temperature, not pressure, drives the specification — with the higher classes serving hot high-pressure steam. All three facings are available: SWRF the default, SWFF for cast and lined mates, SWRTJ where the rating demands it, with high-temperature sealing guidance riding on the quotation. Put the pipe schedule on the enquiry — the through-bore is matched to the pipe ID — and the design temperature, which sets the governing B16.5 rating; our quotations state it per class.
What details are needed to get an accurate Incoloy 800H socketweld flange quotation?
Six elements plus commercial terms: (1) size — ½" to 3" NB; (2) pressure class — 150 to 1500, with the design temperature, which governs the rating and — decisively in this family — the grade; (3) facing — SWRF, SWFF or SWRTJ with ring number; (4) the pipe schedule, so the through-bore matches the pipe ID; (5) the grade line — Incoloy 800H, ASTM B564, UNS N08810 or W.Nr. 1.4958 all name the same metal — noting whether dual-certified 800H/800HT material is acceptable, which simplifies supply; (6) certification — EN 10204 3.1 with solution-anneal and grain-size records (our standard) or 3.2 witnessed, PMI as applicable. Add quantity and destination; quotations normally within 24 hours.
Who manufactures Incoloy 800H socketweld flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing Incoloy 800H (ASTM B564, UNS N08810) socket weld flanges from ½" to 3" NB (larger to order) in Classes 150-1500 — each forged from certified controlled-carbon heats, solution-annealed with furnace charts and grain-size records against the heat number, machined on dedicated nickel-alloy stations with sulphur-free lubricants, gauged socket depth and schedule-matched bore, PMI-checked, and laser-marked with grade, size, class, schedule and heat number. Supplied with EN 10204 3.1/3.2 certification and WPS guidance, alongside the plain 800, 800HT, 825 and 925 siblings and the full nickel-alloy socketweld range this series covers. Exported to more than 50 countries.
