Applications — flanges and forgings by industry
The same flange can be right in one plant and wrong in another. The industry determines the design code, the corrosion allowance, the temperature range and the inspection regime — and those determine the standard, material and face type.
The notes below are a starting point for specification discussions, not a substitute for the project's design basis. Send the service conditions and we will confirm the grade and standard.
Oil & gas
Upstream wellheads, gathering lines, transmission pipelines and refinery units. Weld neck flanges are the default for pressure and cyclic duty; A105 for sweet service, F22/F91 for high-temperature hydrogen, duplex for wet sour lines.
Petrochemical
Chemical plants, ethylene crackers and polymer units. 316/316L for chlorides and organic acids, 321/347 where stabilised grades are required, alloy steel for reactor and high-temperature transfer lines.
Power generation
Main steam, reheat and feedwater lines in thermal plants; balance-of-plant piping in combined cycle. F11, F22 and F91 forgings and flanges with documented heat treatment and creep-resistant properties.
Marine & offshore
Propeller shafts, deck machinery, subsea manifolds and platform piping. Duplex 2205 and super duplex 2507 for chloride resistance; class-approved forgings and third-party inspection on request.
Mining & heavy equipment
Crusher shafts, mill pinions and excavator components. 4140/4340 quenched and tempered forgings for high torque and impact; forged gear blanks with grain flow around the tooth root.
Water & desalination
Treatment plants, desalination trains and district heating. Duplex or 316L for seawater and brine, coated carbon steel for treated water, slip-on flanges for economical low-pressure connections.
Specification matrix
| Service | Typical standard | Material | Flange type |
|---|---|---|---|
| Oil & gas, sweet | ASME B16.5 | A105 / A350 LF2 | Weld neck, blind |
| Oil & gas, sour | ASME B16.5 / NACE | A105 (hardness controlled), duplex | Weld neck |
| Refinery, high temperature | ASME B16.5 / B16.47 | F11, F22, F91 | Weld neck, blind |
| Petrochemical, corrosive | ASME B16.5 / EN | 316L, 321, 904L | Weld neck, slip-on |
| Power, main steam | ASME B16.5 | F22, F91 | Weld neck |
| Marine, seawater | ASME / EN / JIS | 2205, 2507, 316L | Weld neck, slip-on |
| Water, low pressure | ASME / EN / DIN | A105, 304 | Slip-on, blind |
Material grades are explained on the materials pages; for sour service read the selection guide.