Views: 1 Author: Site Editor Publish Time: 2026-08-18 Origin: Site
Not long ago, a long-term Italian client placed an urgent order for ASTM A182 F51 duplex stainless steel flanges for a key offshore project with a tight schedule.
We quickly reorganized internal resources—raw material and production scheduling were given top priority. The flanges were manufactured and shipped within the client's deadline. The project timeline was not affected.
This client has worked with us for years, from early trial orders to major marine engineering projects. Trust is built through on-time delivery and consistent quality. Long-term clients are valuable to us. When urgent needs come up, we focus on solving problems, not on calculating costs.
We see ourselves as more than just a supplier—we want to be dependable support behind our clients' projects. Whether it's F51 duplex steel or other materials, our strength is not just manufacturing. It's about turning "too late" into "just in time" with speed and accountability.
If you're looking for a duplex flange supplier you can count on, feel free to reach out.
The ASTM A182 F51 duplex stainless steel flange (UNS S31803 / S32205) has a dual-phase structure of about 50% austenite and 50% ferrite. This balance gives both good toughness and weld ability from the austenitic phase, plus high strength and resistance to chloride stress corrosion from the ferritic phase.
It is widely used in offshore, petrochemical, and shipbuilding applications.
Element | C | Mn | P | S | Si | Ni | Cr | Mo | N |
ASTM A182 F51 (Min) | - | - | - | - | - | 4.50 | 21.00 | 2.50 | 0.08 |
ASTM A182 F51 (Max) | 0.03 | 2.00 | 0.030 | 0.020 | 1.00 | 6.50 | 23.00 | 3.50 | 0.20 |
Material | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Reduction of Area (%) |
ASTM A182 F51 | 620 min | 450 min | 25 min | 45 min |
With high chromium, molybdenum, and nitrogen, the PREN value is 34–35—well above 304/316L. This makes it suitable for aggressive corrosive environments.
In seawater, salt spray, and sour gas environments, F51 offers better pitting and crevice corrosion resistance than 316L. It also resists sulfide stress corrosion cracking (SCC)—a key reason it's used on offshore platforms and in sour service fields.
F51 has a minimum yield strength of 450 MPa—about twice that of SS316L. This allows thinner flange walls, reducing weight and material costs. That's a clear advantage for weight-sensitive floating structures.
Even with about 50% ferrite, F51 retains good impact toughness at low temperatures. With proper welding and solution annealing, weld joint performance stays reliable in cold marine environments.
F51 costs less than nickel alloys or titanium, and lasts longer than standard stainless steels. Over the full project life cycle, it offers solid overall value.
We manufacture ASTM A182 F51 duplex flanges to ASME B16.5, ASME B16.47, EN 1092-1, and other standards.
Available types:
Flange Type | Typical Use |
Weld Neck (WN) | High temp/pressure, cyclic loading—common for main marine pipelines |
Slip-On (SO) | Medium/low-pressure, easy installation |
Plate (PL) | Low-pressure, non-critical services—economical |
Blind (BL) | Pipe end closures, maintenance openings, test ports |
Socket Weld (SW) | Small-bore high-pressure piping |
Threaded (THD) | Where welding is not practical |
Pressure: Class 150 to Class 2500 (PN6 to PN100)
Size: 1/2" to 60" (larger on request)
ASTM A182 F51 duplex stainless steel flanges are used in:
Offshore & Marine: Seawater cooling, firewater, process piping
Oil & Gas: Wellhead trees, sub-sea manifolds, sour H₂S/CO₂ service
Chemical & Petrochemical: Reactor nozzles, heat ex-changers, corrosive media
FGD Systems: Absorber slurry lines, oxidation air piping
Shipbuilding: Ballast water treatment, loading arm connections
Duplex flange performance depends on careful metallurgical and thermal processing. We follow ASTM A182 closely.
Key controls:
Forging temperature: 950–1150°C to avoid harmful phases;
Solution annealing: 1020–1100°C, water quenched—keeps austenite/ferrite balanced;
NDT: Penetrant (PT) and ultrasonic (UT) testing as needed;
Mechanical testing: Tensile, impact, hardness, intergranular corrosion on each batch;
Third-party inspection: BV, SGS, TUV reports available on request;
All products come with traceable material certificates and dimensional inspection records.
ASTM A182 F51 duplex stainless steel flanges offer high strength and good corrosion resistance—a combination that is replacing traditional austenitic steels in demanding services. For engineers and buyers, choosing F51 is a sound investment in long-term system reliability.
If you need a dependable duplex flange supplier, or have an urgent project, we're ready to help. Contact us today.
Request a quote or technical data for ASTM A182 F51 flanges—we're here to assist.
