ASTM A182 F55 Weld Neck Flanges — Super Duplex S32760 (Zeron 100 Type)
Tesco Steel & Engineering forges ASTM A182 F55 weld neck flanges in super duplex stainless steel UNS S32760 — Werkstoff Nr. 1.4501, the Zeron 100 type alloy — from 1/2″ NB to 56″ NB, in ASME B16.5 Class 150–2500 and European PN patterns. Beyond the 25Cr super duplex base, F55 adds deliberate tungsten and copper and carries a guaranteed PREN of 40 minimum in the specification itself — certified seawater resistance on every heat, plus extra margin in crevices and hot acids where even F53 (2507) is tested. Mating A790 S32760 pipe on platforms, FPSOs and desalination plants, at 750/550 MPa minimums. Solution annealed, with PMI, ferrite testing, ASTM A923, G48 and EN 10204 3.1/3.2 on request. ISO 9001:2015, made in Mumbai, India — exported worldwide.
A182 F55 · UNS S32760 · Zeron 100 Type
1.4501 · 25Cr-7Ni-3.5Mo-N-W-Cu
1/2″ – 56″ NB
Class 150 – 2500 · PN 2.5 – 400
Guaranteed PREN ≥ 40
W + Cu · Crevice & Acid Margin
ISO 9001:2015 · Exported Worldwide
ASTM A182 F55 Weld Neck Flange — Super Duplex S32760 (Zeron 100 Type), Technical Specifications
What is an ASTM A182 F55 Weld Neck Flange?
ASTM A182 F55 is the forged-flange grade of super duplex UNS S32760 (1.4501) — the Zeron 100 type alloy: 25% chromium, 7% nickel, molybdenum and high nitrogen, plus tungsten and copper that no other mainstream super duplex carries. Uniquely, the specification guarantees PREN ≥ 40 on every heat — certified seawater resistance by chemistry. An F55 weld neck flange pairs that pedigree with a long tapered hub butt-welded to the pipe, bore matched to schedule, joint fully radiographable, at 750 MPa tensile / 550 MPa yield minimums.
The two extra elements earn their place: tungsten counts toward the PREN formula alongside molybdenum and is credited with better crevice corrosion resistance — the attack that starts under gaskets, washers and deposits in seawater — while copper buys margin in reducing acids like sulphuric. That is why seawater pump, valve and flange specifications so often name S32760 explicitly, and why the alloy's trade name became shorthand for offshore seawater engineering.
On the ladder it stands beside F53 (2507) — same strength class, same raw-seawater credential — above duplex 2205 (F51), and below only the 6-Mo austenitics and nickel alloys. The project specification usually picks between the two super duplexes; we forge both, so either callout is covered from one source.
Also searched as: Zeron 100 flange, UNS S32760 flange, 1.4501 flange, super duplex F55 flange, S32760 WNRF flange, SA182 F55 flange — all refer to the product on this page.
Chemical Composition of ASTM A182 F55
| C | Mn | Si | P | S | Cr | Mo | Ni | N | Fe |
|---|
| 0.030 max | 1.00 max | 1.00 max | 0.030 max | 0.010 max | 24.00-26.00 | 3.00-4.00 | 6.00-8.00 | 0.20-0.30 | Bal |
Values in weight %. S32760 additionally requires the grade's signature tungsten 0.50–1.00% and copper 0.50–1.00%, and — uniquely among the super duplexes — a compositional PREN = %Cr + 3.3×(%Mo + 0.5×%W) + 16×%N of 40 minimum, demonstrated heat by heat on the mill certificate.
Mechanical Properties of ASTM A182 F55
| Tensile Strength, MPa | Yield Strength, Min, MPa | Elongation % min. |
|---|
| 750 | 550 | 25 |
Minimums per ASTM A182 — 750 MPa (109 ksi) tensile and 550 MPa (80 ksi) yield, the same yield floor as F53 and more than three times that of austenitic 316L. The mandatory solution-annealed condition (which dissolves harmful intermetallic phases) is documented on every certificate.
Equivalent Grades of ASTM A182 F55
| Standard | Werkstoff Nr. | UNS |
|---|
| Alloy F55 (Super Duplex) | 1.4501 | UNS S32760 |
Also written EN X2CrNiMoCuWN25-7-4 and known worldwide by the Zeron 100 trade name. System partners: A790 seamless pipe, A928 welded pipe and A815 butt-weld fittings in S32760. The tungsten-free sibling F53 (2507) and standard duplex 2205 (F51) complete our duplex flange range.
ASTM A182 F55 Weld Neck Flange Specifications
| ASTM A182 F55 Weld Neck Flanges are available in the following specifications: |
|---|
| Size | 1/2"NB to 56"NB |
| Class | 150#, 300#, 400#, 600#, 900#, 1500#, 2500# |
| Sch (Schedule) | XS, XXS, STD & Schedule 20, 40, 80, 160 |
| Pressure Ratings | PN 2.5 - PN 400 |
| Standards | ASME B16.5, ASME B16.47, EN 1092-1 Type 11, DIN 2631–2635, BS 4504 |
| Condition | Solution Annealed, intermetallic-free per ASTM A923 on request |
| Other Services | Pickling & passivation on ASTM A182 F55 Weld Neck Flanges
Sand Blasting on ASTM A182 F55 Weld Neck Flanges
Shot Peening on ASTM A182 F55 Weld Neck Flanges
Ferrite count, ASTM A923, G48 & PMI testing
Project-specific marking, wrapping & export packing |
Why S32760 When the Specification Says Seawater
PREN ≥ 40 Guaranteed, Not Typical
The compositional PREN minimum is written into the S32760 specification — every heat certifies above the seawater threshold by chemistry, demonstrated on the mill certificate.
Tungsten Against Crevices
Crevice corrosion under gaskets, washers and deposits is the classic seawater failure mode — the tungsten addition is credited with pushing the critical crevice temperature higher than tungsten-free super duplex.
Copper Against Acids
The copper addition buys resistance in reducing acids like sulphuric — extending F55 into acidic chloride streams that test other stainless families.
Three Times the Yield of 316L
550 MPa minimum yield takes weight out of piping, bolting and structures — on offshore topsides, saved kilograms are saved money twice over.
Offshore Paperwork Ready
Ferrite counts, ASTM A923, G48 at specified temperatures, −46 °C impacts, 3.2 witness — the testing scope NORSOK-style specifications demand, delivered with the flange.
Welding Super Duplex F55 — Tighter Windows, Same Rules
F55 welds like any super duplex — on discipline. Use over-alloyed 2594 filler (ER2594 / E2594), or an S32760-matching consumable where the project requires tungsten-bearing weld metal; hold heat input moderate, cap interpass temperature around 100–150 °C, and skip PWHT — solution annealing is a mill operation, not a field one. The rich chemistry precipitates sigma phase quickly in careless thermal cycles, so offshore specifications back the weld procedure with ferrite measurement, ASTM A923 screening and often G48 corrosion tests on production welds.
Temperature window: keep long-term service between roughly −46 °C and 250 °C — the alloying that guarantees PREN ≥ 40 also speeds 475 °C embrittlement and sigma formation above the window.
Where ASTM A182 F55 Weld Neck Flanges Are Used
Raw seawater systems first: lift, injection, firewater ring mains and cooling circuits on platforms and FPSOs, and the seawater pumps and valves where the Zeron 100 name was made. Then desalination high-pressure trains, chemical plants running hot chlorides and acidic streams, flue gas desulphurisation, pulp and paper bleach plants and marine engineering — anywhere crevice attack or acidic chlorides push past standard super duplex. Machined weld neck production below:
ASTM A182 F55 Weld Neck Flanges — Machined Production Stock
ASTM A182 F55 Weld Neck Flange Dimensions
F55 weld neck flanges share their dimensions with every other material in the same class — OD, thickness, hub, bore, bolt circle and bolting per the standard tables. Full ASME B16.5 charts:
European PN dimensions are published on the EN 1092-1 Type 11, DIN 2631–2635 and BS 4504 pages.
Price List & How to Order
Super duplex pricing tracks nickel and molybdenum plus the testing scope, so we quote live with a stated validity rather than publish a static list. To get a firm quotation, usually within 24 hours:
1
List your requirement — size (NB), class or PN, standard (ASME B16.5 / B16.47 / EN / DIN / BS), grade (F55 / S32760 — or F53 if either super duplex is acceptable), pipe schedule or bore, and quantity.
2
Add the testing scope — ferrite count, ASTM A923, G48 with test temperature, impact at −46 °C, 3.2 witness, NORSOK or project specifications.
ASTM A182 F55 Weld Neck Flanges — Frequently Asked Questions
What is an ASTM A182 F55 weld neck flange?
It is a weld neck flange forged from ASTM A182 grade F55 — super duplex stainless steel UNS S32760, the Zeron 100 type alloy of 25% chromium, 7% nickel, molybdenum, high nitrogen plus deliberate tungsten and copper. The long tapered hub is butt-welded to the pipe with the bore matched to the pipe schedule, giving a radiographable, fatigue-resistant joint in a grade whose specification guarantees a pitting resistance number of 40 minimum — raw seawater territory.
What is Zeron 100 and how does it relate to F55?
Zeron 100 is the trade name under which this alloy was developed and made famous in offshore and seawater engineering; UNS S32760 is its universal designation and ASTM A182 F55 is its forged-flange grade. Specifications written around any of the three describe the same material. Our flanges are certified to A182 F55 / S32760, which satisfies enquiries that arrive asking for the trade name.
What is the difference between F55 (S32760) and F53 (S32750)?
Both are 25Cr super duplex grades of near-identical strength and general performance. F55 adds deliberate tungsten and copper — about 0.5 to 1% of each — which its specifications credit with extra resistance in hot acids and seawater crevices, and uniquely it carries a compositional PREN minimum of 40 written into the standard, so every heat is guaranteed above the seawater threshold by chemistry, not just by typical values. F53 (2507) is the more widely stocked generic. The project specification usually decides; we forge both.
What does the guaranteed PREN minimum of 40 mean?
The S32760 specification requires each heat's chemistry to satisfy PREN = %Cr + 3.3×(%Mo + 0.5×%W) + 16×%N at 40 or higher — the offshore industry's traditional threshold for seawater resistance. That turns a rule of thumb into a certified property: the mill certificate demonstrates the number, heat by heat. In practice S32760 runs critical pitting temperatures above 50 °C in G48 testing, comfortably clear of warm raw and chlorinated seawater.
What temperature range can F55 super duplex flanges be used in?
Roughly -46 °C to 250 °C. The ceiling is metallurgical: the rich chemistry that buys corrosion resistance also speeds sigma phase formation and 475 °C embrittlement, so long-term service stays below about 250 °C. The lower limit reflects ferrite toughness, with impact testing at -46 °C standard for offshore specifications. Inside that window, F55 pairs near-nickel-alloy corrosion performance with twice the strength of austenitic stainless.
What are the equivalent designations for A182 F55?
UNS S32760; Werkstoff Nr. 1.4501; EN X2CrNiMoCuWN25-7-4; and the Zeron 100 trade name. Its system partners share the chemistry: A790 seamless super duplex pipe, A815 fittings and A928 welded pipe in S32760. An enquiry in any of these designations is quoted as the same material.
What is the chemical composition of ASTM A182 F55?
Per our supply practice: carbon 0.030% max, manganese 1.00% max, silicon 1.00% max, phosphorus 0.030% max, sulphur 0.010% max, chromium 24.00 to 26.00%, molybdenum 3.00 to 4.00%, nickel 6.00 to 8.00% and nitrogen 0.20 to 0.30%, balance iron — plus the grade's signature additions of tungsten 0.50 to 1.00% and copper 0.50 to 1.00%, with the compositional PREN required to reach 40 minimum on every heat.
What are the mechanical properties of A182 F55 flanges?
Minimum tensile strength 750 MPa (109 ksi), minimum yield strength 550 MPa (80 ksi) and minimum elongation 25% — the same 550 MPa yield floor as F53, more than three times that of austenitic 316L. The mandatory solution-annealed condition, which dissolves harmful intermetallic phases, is documented on every certificate.
Which pipe grades do F55 weld neck flanges mate with?
ASTM A790 seamless super duplex pipe in UNS S32760 is the standard partner, with A928 welded pipe on larger diameters and A815 butt-weld fittings completing the system. The weld neck bore is machined to the pipe schedule you state, so the bore runs flush through the joint and the bevel arrives ready for a matched-chemistry butt weld.
How are super duplex F55 flanges welded to pipe?
With over-alloyed super duplex filler — 2594 (ER2594 / E2594) or an S32760-matching consumable where the project requires tungsten-bearing weld metal — moderate heat input, interpass temperature capped around 100 to 150 °C, and no post-weld heat treatment in normal practice. Super duplex punishes careless thermal cycles with sigma phase, so offshore specifications back the procedure with ferrite measurement, ASTM A923 screening and often G48 corrosion tests on production welds.
Why do the tungsten and copper additions matter?
Tungsten works alongside molybdenum against localized attack — it counts toward the PREN formula at half weight and is credited with improving crevice corrosion resistance, the failure mode that starts under gaskets, deposits and bolted joints in seawater. Copper improves resistance to reducing acids such as sulphuric, extending F55 into acidic process streams that test other super duplexes. Together they are why seawater pump, valve and flange specifications so often name S32760.
What testing and certification do you supply with F55 flanges?
Every lot ships with EN 10204 3.1 mill test certificates covering chemical analysis including nitrogen, tungsten and copper, the calculated PREN, mechanical properties and the solution-anneal record — with 3.2 certification witnessed by Lloyd's, DNV, BV or TÜV on request. We also offer PMI, ferrite count verification, ASTM A923 intermetallic-phase testing, ASTM G48 pitting tests at specified temperatures and impact testing at -46 °C, with full heat-number traceability.
Are F55 flanges suitable for sour service (NACE)?
Yes, within the limits ISO 15156 / NACE MR0175 sets for super duplex stainless steels — the standard defines acceptable H2S partial pressures, chloride levels and temperatures, and requires the correct solution-annealed, intermetallic-free condition. Offshore production systems use S32760 extensively inside those limits. State the sour-service requirement in your enquiry and material, testing and hardness control are aligned to it.
Where are ASTM A182 F55 weld neck flanges used?
Raw seawater systems above all — lift, injection, firewater and cooling circuits on platforms and FPSOs, plus seawater pumps and valves where the alloy made its name. Beyond offshore: desalination high-pressure trains, chemical plants running hot chlorides and acidic streams, flue gas desulphurisation, pulp and paper bleach plants and marine engineering — anywhere crevice corrosion or acidic chlorides push past standard super duplex.
What sizes and standards do you manufacture F55 weld neck flanges in?
From 1/2 inch NB to 56 inch NB: ASME B16.5 Class 150 to 2500 up to 24 inch, ASME B16.47 above, and European PN 2.5 to PN 400 patterns to EN 1092-1 Type 11, DIN and BS 4504. Raised face is standard, ring joint for high-class offshore service on request, and every bore is machined to the mating pipe schedule from Sch 10 through XXS.
Do you keep A182 F55 weld neck flanges in stock? What is the lead time?
F55 moves in project quantities, so common offshore sizes in Class 150 to 600 rotate through production with popular items often available, while larger diameters, higher classes and witness-tested lots are forged to order — typically 3 to 5 weeks. Prices track nickel, molybdenum and the testing scope, so quotations carry a validity period. Send the size list and we confirm the stock position the same day.
What information should I include in an F55 flange enquiry?
Six things: size (NB), pressure class or PN rating, dimensional standard (ASME B16.5, B16.47 or EN/DIN/BS), grade (F55 / S32760 — or F53 if the project allows either super duplex), pipe schedule or bore, and quantity. Add the testing scope — A923, ferrite count, G48 with test temperature, impact at -46 °C, 3.2 witness, NORSOK or project specs — since super duplex paperwork is specification-driven. With these details we return a firm quotation, usually within 24 hours.
Do you export ASTM A182 F55 flanges outside India?
Yes. Tesco Steel & Engineering is an ISO 9001:2015 certified manufacturer based in Mumbai, and F55 super duplex flanges ship to offshore contractors, desalination projects and chemical plants across the Middle East, Europe, Africa, Southeast Asia and the Americas. Flanges travel pickled, face-protected and seaworthy-packed, with full heat-number and test traceability.
