A flange has to seal a joint against pressure for the design life of the line, often in seawater, sour or acid service where standard austenitic stainless steels will not survive.

We supply the bar and plate that flanges are machined from, across the duplex, super duplex and nickel ranges, from stock in the UK and USA.

Which alloy for seawater and subsea flanges?

Super duplex is the reference: Ferralium® 255 (S32550 / A182 F61), Alloy 32750 (F53) and Alloy 32760 (F55), all with a PREN above 40. Ferralium® 255 has the edge in large, thick sections, where sigma phase formation is less likely than with other super duplex grades.

Which alloy for sour and high-pressure flanges?

Alloy 2205 covers general pressure duty, moving to super duplex and then Alloy 718 and Alloy 725 for high-strength sour service, to NACE MR0175 and ISO 15156 subject to the hardness limits the standard sets.

Which alloy for acid and chemical-process flanges?

Alloy 825 and Alloy 625 handle aggressive acid streams; 2205 and the super duplex grades cover the middle ground at lower cost.

What are the ASTM A182 F-grade equivalents?

F51 is 2205 (S31803/S32205), F53 is Alloy 32750, F55 is Alloy 32760, and F61 is Ferralium® 255 (S32550). Provided the specification calls out the F-grade or UNS number, the material is directly equivalent and we can supply the documentation to demonstrate it.

Also known as

Ferralium® 255 is the Langley Alloys trade name for the super duplex stainless steel UNS S32550 (A182 F61). Alloy 32760 is equivalent to UNS S32760 (F55), also known as Zeron 100®, a trademark of Rolled Alloys. Alloy 32750 is equivalent to UNS S32750 (F53), also known as SAF 2507®, a trademark of Alleima. Alloy 2205 is the 22 percent chromium duplex grade UNS S31803/S32205 (F51). Alloy 625, Alloy 718 and Alloy 725 are equivalent to UNS N06625, N07718 and N07725, sold elsewhere as Inconel® 625, Inconel 718 and Inconel 725, trademarks of Special Metals. Alloy 825 is equivalent to UNS N08825, sold elsewhere as Incoloy® 825, a trademark of Special Metals. If your drawing calls out a trade name we have not listed, send it to us and we will confirm the matching grade.

Typical flange work

Weld-neck, blind, slip-on and ring-type joint flanges, machined from solid bar or cut from plate. A one-piece flange from bar or plate shortens lead time against a forging.

Why buy from us

  • Stock across the duplex, super duplex and nickel range, so you can quote and deliver without waiting on a mill run.
  • Sawing and cut-to-length to reduce machining time.
  • Technical support on grade selection and international equivalence, including competitor trade names.

We supply the material as bar and plate for flanges, which are machined from solid or cut from plate.

Related sectors: oil and gas, marine and offshore, and chemical processing. Related applications: fittings and valves. See also our material calculators for PREN and equivalents lookups.