PTFE Rings
Raised Face PTFE Rings
Raised Face PTFE Rings is a group of 64 IMPA-coded items (codes 813401–813474) under PTFE Rings in the Packing & Jointing section (IMPA 81). All of them are priced per piece. Every item in the list is PTFE. The list runs through 31 metric sizes from 18×2 mm to 645×2 mm.
Buying guide
These are flat ring gaskets cut from PTFE, sized to sit inside the bolts on a raised-face flange. The group has four series. PO850 (2 mm) and PO860 (3 mm) are for PN16 flanges, nominal sizes 10 to 600. PO870 (2 mm) and PO880 (3 mm) are for ASA 150 lb flanges, sizes 15 to 300. Each line gives the outside diameter, inside diameter and thickness in millimetres.
PTFE is chosen for its chemical resistance, for services where a rubber or fibre gasket would be attacked by the medium.[1]
How to specify it
Order by flange standard and rating, nominal size and thickness, or quote the full IMPA line, which carries all three plus the dimensions. Check the outside diameter against the raised face and the inside diameter against the bore. The PN16 and the 150 lb rings of the same nominal size are different sizes, so they are not interchangeable.
Use the thinnest gasket the flanges allow. Garlock’s installation advice is to use the thinnest possible gasket, with thicker ones only for warped, bowed or badly pitted flanges. It also prefers ring gaskets to full-face gaskets on metric flanges, because full-face gaskets need more bolt load.[1]
Tell the supplier the medium and temperature. Plain PTFE is not the only option: filled and restructured PTFE sheets are made to reduce cold flow.[1]
Rules and certificates
Dimensions of non-metallic flat gaskets for PN-designated flanges are set by EN 1514-1. Its 2024 edition covers gaskets with or without inserts, up to PN 63 and DN 4000, for flanges to EN 1092-1 to -4.[2]
Plain PTFE has known limits as a gasket. Garlock’s history of PTFE gasketing lists skive marks that made initial sealing difficult, cold flow that caused leakage and premature failure, and trouble with temperature and pressure cycling. Its GYLON range was developed to reduce creep and cold flow.[1]
Heat is the other limit. PTFE subjected to temperatures above 250 °C starts to decompose slowly, increasing rapidly above 400 °C, and the fumes should not be inhaled.[3]
At fitting, centre the gasket on the raised face, tighten in a star pattern in steps (Garlock gives 30 %, 70 % and 100 % of the specified torque), and never put metal-based anti-seize or liquid compounds on the gasket. Garlock does not recommend retorquing a pressurised system. It advises any retorque at room temperature, 12 to 24 hours after installation.[1]
Questions buyers ask
- Why do PTFE gaskets leak after a while?
- Cold flow: plain PTFE creeps under bolt load, so the bolt stress relaxes. Garlock names cold flow as the cause of leakage and premature failure in early PTFE gaskets. Restructured or filled PTFE grades are made to reduce it.
- What temperature can a PTFE flange gasket take?
- Keep it well below 250 °C, where PTFE starts to decompose. Check the maker’s rating for the exact sheet, since the safe pressure falls as temperature rises.
Sources
- Garlock: GYLON PTFE gasketing catalogue (history, properties, installation recommendation)
- Genorma: EN 1514-1:2024, Flanges and their joints, dimensions of gaskets for PN-designated flanges, part 1 non-metallic flat gaskets (scope)
- Flexitallic: Spiral wound gaskets brochure (styles CG, CGI, R, RIR; materials, colour coding, ordering, assembly)
Published by Sherif Awad, founder of GeoMarineHub — in ship supply since 1990, a family business since 1981 (45 years). Last checked .
At a glance
Part of Packing & Jointing (IMPA section 81): Gaskets, gland packing, jointing sheet, O-rings, oil seals and sealing tapes.
Post the ones you need as a requirement and verified suppliers activated at your port bid on them — sealed, so nobody sees another bid.
- Items
- 64
- IMPA codes
- 813401–813474
- Priced
- per piece
- Materials
- PTFE
- Sizes
- 18×2 mm – 645×2 mm
Items
Most requested sections