Flange Gasket Selection Guide: Materials, Types & Pressure Classes
Every flanged joint is a system: the flange faces, the bolting, and the gasket all have to be matched to the media, temperature, and pressure class. Pick the gasket last — after you know the other variables — and most leak problems never happen. Here's the selection logic our counter team walks buyers through every day.
Start With the Flange Face
Raised face (RF) flanges take sheet, spiral wound, or kammprofile gaskets. Ring type joint (RTJ) grooved flanges take metal ring gaskets only. Flat face (FF) flanges — common on cast iron and FRP equipment — need full-face soft gaskets so the bolting doesn't crack the flange. Tongue-and-groove and male-female faces use confined flat gaskets.
Match the Gasket Type to Pressure Class
| Class | Typical choice |
|---|---|
| 125 / 150 | Compressed sheet, rubber, or spiral wound |
| 300 – 600 | Spiral wound or kammprofile |
| 900 – 2500 | Spiral wound w/ inner ring, kammprofile, or RTJ |
Material Temperature Limits
Rules of thumb that keep joints tight: EPDM and nitrile sheet to about 250°F, compressed non-asbestos fiber to 400–700°F depending on binder, PTFE to 500°F, flexible graphite to 850°F in oxidizing service, and metal-based gaskets beyond that. Chemical compatibility trumps temperature — PTFE for aggressive acids and caustics, graphite for steam and hydrocarbons.
Sheet vs Spiral Wound vs Kammprofile
Cut sheet gaskets are economical for low-pressure, steady-state service. Spiral wound gaskets handle thermal cycling and pressure swings. Kammprofile (grooved metal core with soft facing) gives the highest recovery and is increasingly the default for heat exchangers and problem flanges. If a joint keeps leaking on sheet, upgrading to kammprofile usually ends the callbacks.
Installation Matters as Much as Selection
Clean the flange faces, verify alignment, use new gaskets on every breakout, lubricate the studs, and torque in a cross pattern in three or more passes to the target gasket stress. A perfect gasket in a misaligned, under-torqued joint will still leak.
Custom Gaskets, Cut to Spec
We cut custom gaskets to your dimensions and stock standard ANSI sizes across sheet, spiral wound, and metallic styles. Use the quote form at the top of this page with your flange size, class, media, and temperature — pricing and lead time back in 1–2 business hours.