Flange Materials

Guide to Pipe Flange Material Specifications and Grades

Flange material selection depends on the service conditions: operating temperature, pressure, corrosivity of the process fluid, and applicable design codes. The material must be compatible with the connected piping and must meet the pressure-temperature ratings required by the system design.

Carbon Steel Flanges

ASTM A105 and A350 LF2. The most common flange material for general industrial, refinery, and power plant service.

Stainless Steel Flanges

ASTM A182 F304, F316, and dual-grade specifications. Corrosion-resistant flanges for chemical, food, and marine applications.

Alloy Steel Flanges

ASTM A182 chrome-moly grades (F11, F22, F91). High-temperature flanges for boiler and refinery piping.

Chrome Steel Flanges

Higher-chrome Cr-Mo grades (F5, F9, F91) for oxidation and sulfidation resistance in refinery service.

Duplex Stainless Steel Flanges

ASTM A182 F51 (2205) and F53 (2507). High-strength, corrosion-resistant flanges for offshore and chemical service.

Titanium Flanges

ASTM B381 grades. Lightweight, corrosion-resistant flanges for extreme chemical environments and seawater service.

High Yield Flanges

ASTM A694 grades F42-F70. High-strength carbon steel flanges for pipeline and offshore applications.

Material Selection Considerations

  • Temperature — Carbon steel (A105) is suitable from -20°F to ~1000°F. Below -20°F, use low-temperature grades (A350 LF2). Above 1000°F, use chrome-moly alloys (F11, F22, F91).
  • Corrosion — Stainless steel for general corrosion resistance. Duplex for chloride environments. Titanium for extreme chemical service.
  • Strength — High yield (A694) when the design code allows higher allowable stress. Duplex when both strength and corrosion resistance are needed.
  • Cost — Carbon steel is the most economical. Consider lap joint flanges with alloy stub ends to reduce material costs on exotic piping.

Related References