Gasket material
Filled PTFE Gasket Material
Filled PTFE is PTFE compounded with silica, glass or barium sulfate so the sheet holds its thickness under bolt load instead of creeping. It is the chemical-service flange gasket for steel piping, valves and pumps, sold under names such as GYLON®. We cut it to your drawing on the waterjet.
- Family
- Filled PTFE sheet
- Temperature
- -268 C to 260 C (-450 F to 500 F)
- Thickness
- 1/16 in and 1/8 in
- Formats
- Sheets 30 x 30 in, 30 x 60 in, 60 x 60 in
- Designations
- ASTM F104 (fluoropolymer group)
- Product
- Sheet gaskets waterjet-cut to your drawing in Orange, California
Figures are the cited maker or standards values; the sheet datasheet and your application govern the final choice.
Every common gasket sheet material is quick for us to source, and we cut it to your print on our waterjet.
What filled PTFE seals
Filled PTFE keeps the chemical resistance of the polymer and fixes its weakness: virgin sheet cold-flows under sustained bolt load and the joint loosens. The filler holds the thickness, so the gasket keeps its stress in steel flanges carrying strong acids, solvents, hydrocarbons and caustics [S1]. Silica-filled sheet is the general chemical grade; other fillers are chosen for specific media such as hydrofluoric acid.
The cited grade is rated to 260 C and 1200 psi, with the pressure-temperature product falling as the sheet gets thicker [S1]. On soft or uneven flanges that cannot take the seating load, expanded PTFE seals more easily.
Naming it on the print
Most prints name the maker's style, GYLON 3500 for example, because the filler and its ratio set the fluid resistance. ASTM F104 classifies fluoropolymer gasket sheet and the PTFE gasket page lists the digits. Give the style or the callout with the thickness and the sheet is sourced to it.
Specifications
Filled PTFE specifications
| Property | Value (in / mm, C / F as stated) | Source |
|---|---|---|
| Composition | PTFE with silica filler (GYLON Style 3500) | [S1] |
| Temperature | Minimum -268 C (-450 F); maximum 260 C (500 F) | [S1] |
| Pressure | 1200 psi (83 bar) maximum; P x T 350,000 F x psig at 1/16 in, 250,000 at 1/8 in | [S1] |
| Thickness | 1/16 in and 1/8 in (1.6 mm and 3.2 mm) | [S1] |
| Formats | Sheets 30 x 30 in, 30 x 60 in, 60 x 60 in; fawn | [S1] |
| Designations | ASTM F104 classifies fluoropolymer gasket sheet; the type and class digits are on the PTFE gasket page | [S2] |
How we cut it
Gaskets are waterjet-cut to your drawing in Orange, California. Send a DXF, DWG or PDF with the thickness, the material or the specification callout, and the quantity. There is no die to build, so a single prototype and a repeat run go through the same setup, and a revision needs only a new file. The sheet comes from the sheet makers we buy from, to the callout on your print; the cutting is ours. Filled PTFE is among the most expensive sheets we cut, and the waterjet nests parts tightly with no die-skeleton waste; laser cutting is never used on PTFE.
Where Filled PTFE is used, and the usual alternatives
The print or the sheet datasheet governs; these are the sheets usually specified instead:
- Expanded PTFE: when the flange is glass-lined, plastic or uneven and the bolt load is low.
- Solid PTFE: when the print names virgin sheet and the load is light.
- Compressed non-asbestos fiber: when the medium is water, steam or oil.
- Viton® sheet: when the joint needs a rubber gasket that resists fuels and hot oil.
Related gasket materials: Expanded PTFE (ePTFE) Gasket Material, PTFE Gasket Material, Compressed Non-Asbestos Fiber (CNAF) Gasket Material, Viton (FKM) Gaskets. The full index is on the gaskets hub; send the drawing through request a quote.
Frequently asked
Why fill PTFE at all?
Virgin PTFE creeps under sustained bolt load and the flange loses its seal. A mineral filler such as silica holds the sheet's thickness so the joint stays tight.
What media suit filled PTFE?
Strong acids, caustics, solvents and hydrocarbons in steel piping and equipment. Specific fillers suit specific media, so name the style or the filler your print specifies.
How thick should the gasket be?
The cited sheet comes in 1/16 in and 1/8 in. Thinner sheet holds more pressure-temperature product; thicker sheet seals rougher faces.
Can you cut GYLON by style number?
Yes. Name the style, or write filled PTFE with the filler, and the sheet is sourced to match before cutting.
Is filled PTFE laser-cut?
No. PTFE decomposes under a laser and gives off toxic gas. The waterjet cuts it clean.
Sources
- [S1] Garlock® GYLON Style 3500 PTFE Sheet, Gasket Supply, https://www.gasketsupply.com/products/garlock-gylon-style-3500-ptfe-sheet, accessed 2026-09-13.
- [S2] ASTM F104-11(2020), Standard Classification System for Nonmetallic Gasket Materials, https://store.astm.org/f0104-11r20.html, accessed 2026-09-13.
Garlock and GYLON are trademarks of Garlock Sealing Technologies; Viton is a trademark of The Chemours Company. No affiliation or endorsement is implied.
Related guides
Send the Filled PTFE gasket drawing and the quantity
Upload a DXF, DWG or PDF of the gasket with the quote request, or a photo of the part with a ruler if no drawing exists. Add the sheet thickness, the durometer or grade, the quantity and whether adhesive backing is wanted. Gaskets are cut in our own shop in Orange, California; a Conquest representative replies.
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