Gasket material
Flexible Graphite Gasket Material
Flexible graphite is natural graphite flake expanded and pressed into a foil that seals at temperatures no rubber, fiber or PTFE sheet survives. Homogeneous sheet is cut on our waterjet; tanged sheet, which carries a perforated stainless insert, is supplied cut by the sheet maker or a cutting partner. Both are quoted to your drawing.
- Family
- Flexible graphite, homogeneous or tanged
- Temperature
- To 450 C (842 F) in air, homogeneous foil
- Thickness
- 0.003 in to 0.125 in homogeneous; 0.030 in, 0.060 in, 0.120 in tanged
- Formats
- Sheets 39.4 x 39.4 in (1 m) and 59.1 x 59.1 in; rolls to 39.4 in wide
- Designations
- ASTM F104 (flexible graphite group)
- Product
- Homogeneous sheet waterjet-cut in Orange, California; tanged sheet supplied cut
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 flexible graphite seals
Flexible graphite seals steam, hot oil, exhaust and heat-transfer fluid joints at temperatures beyond every polymer sheet, and it stays chemically inert across nearly the whole pH range. The homogeneous foil is rated to 450 C in air, higher with an oxidation inhibitor, and far higher in an inert atmosphere [S1]. It has no binder, so there is nothing to age, harden or bleed out [S2].
Homogeneous sheet tears easily and is used where the flange fully confines it, in narrow rings, valve bonnets and small covers. Tanged sheet adds a perforated stainless core for blowout resistance and handling strength on larger pipe flanges, rated by the maker from vacuum to 1500 psi [S2, S3].
Homogeneous or tanged, and who cuts it
Homogeneous graphite goes on the waterjet like any other sheet. Tanged graphite does not: the jet lifts the graphite facing off the metal core. Tanged gaskets are supplied cut by the sheet maker or a cutting partner, quoted from the same drawing, so send the print either way and the routing is decided before the quote. Where the joint runs below the fiber sheet's limit, compressed non-asbestos fiber costs less and handles better.
Specifications
Flexible Graphite specifications
| Property | Value (in / mm, C / F as stated) | Source |
|---|---|---|
| Composition, homogeneous | Pure natural graphite flake, no binder (GraFoil®) | [S1] |
| Composition, tanged | Flexible graphite foil laminated to a 0.004 in tanged 316L stainless insert (SIGRAFLEX® BTCSS; Style 2030E) | [S2, S3] |
| Temperature, homogeneous, in air | 450 C (842 F) under normal conditions; 525 C (977 F) with oxidation inhibitor | [S1] |
| Temperature, tanged | -269 C to 500 C (-452 F to 932 F) depending on foil grade; consult the maker above 399 C (750 F) | [S2] |
| Pressure, tanged | Vacuum to 1500 psi | [S2] |
| Density | 70 lb/ft3 flexible graphite (ASTM F1315) | [S2] |
| Thickness, homogeneous | Rolls 0.003 in to 0.060 in; sheets 0.032 in to 0.125 in | [S1] |
| Thickness, tanged | 0.030 in, 0.060 in, 0.120 in (ASTM F104 thickness) | [S2, S3] |
| Formats | Sheets 39.4 x 39.4 in (1 m) and 59.1 x 59.1 in; rolls to 39.4 in wide | [S1, S2, S3] |
| Designations | ASTM F104 classifies flexible graphite sheet; grades are named by the maker (GraFoil GTB, GHE; SIGRAFLEX BTCSS) | [S4, S1, S2] |
How we cut it
Homogeneous graphite gaskets are waterjet-cut to your drawing in Orange, California from sheet sourced to the grade the print names; send a DXF, DWG or PDF with the thickness and the quantity. Tanged and metal-inserted sheet is not a waterjet material, so those gaskets are supplied cut by the sheet maker or a cutting partner and quoted the same way. Say which one the print calls for, or send the print and the routing is decided before the quote.
Where Flexible Graphite is used, and the usual alternatives
The print or the sheet datasheet governs; these are the sheets usually specified instead:
- Compressed non-asbestos fiber: when the joint runs below about 200 C and handling strength matters.
- Mica: when the service is hot, dry gas above the graphite oxidation limit.
- Filled PTFE: when the medium is a strong acid or solvent within the PTFE grade sheet's temperature limit.
- Viton® sheet: when a rubber gasket will do and the fluid is fuel or hot oil.
Related gasket materials: Compressed Non-Asbestos Fiber (CNAF) Gasket Material, Mica Gasket Material, Filled PTFE Gasket Material, Viton (FKM) Gaskets. The full index is on the gaskets hub; send the drawing through request a quote.
Frequently asked
How hot can a graphite gasket run?
The homogeneous foil is rated to 450 C in air under normal conditions and 525 C with an oxidation inhibitor; in an inert atmosphere the limit is far higher. Oxygen, not heat, sets the ceiling.
What is tanged graphite?
Graphite foil laminated to a thin perforated (tanged) stainless steel sheet. The tangs lock the layers together and give the gasket blowout resistance and handling strength.
Do you waterjet-cut tanged graphite?
No. The jet strips the facing off the metal core. Tanged gaskets are supplied cut by the sheet maker or a cutting partner and quoted from the same drawing.
Which thickness should I use?
1/16 in (0.060 in) is the common flange thickness; 1/32 in for flat faces at higher pressure and 1/8 in for rougher faces. The cited tanged sheet comes in 0.030 in, 0.060 in and 0.120 in.
Is graphite safe with oxidizers?
No. Strong oxidizers such as nitric acid attack graphite, and above the air rating the sheet slowly burns away. Use mica or a fluoropolymer sheet instead.
Sources
- [S1] GraFoil Flexible Graphite, NeoGraf Solutions, https://neograf.com/products/grafoil-flexible-graphite/, accessed 2026-09-13.
- [S2] SIGRAFLEX BTCSS datasheet (flexible graphite foil reinforced with tanged stainless steel), SGL Carbon, https://www.sglcarbon.com/pdf/SGL-Datasheet-SIGRAFLEX-BTCSS-EN.pdf, accessed 2026-09-13.
- [S3] Graphite Sheet Laminate with SS316 Tang Insert, Style 2030E, Mineral Seal Corporation, https://minseal.com/graphite-sheet/ss316-tang-insert/, accessed 2026-09-13.
- [S4] ASTM F104-11(2020), Standard Classification System for Nonmetallic Gasket Materials, https://store.astm.org/f0104-11r20.html, accessed 2026-09-13.
GraFoil is a trademark of NeoGraf Solutions; SIGRAFLEX is a trademark of SGL Carbon; Viton is a trademark of The Chemours Company. No affiliation or endorsement is implied.
Related guides
Send the Flexible Graphite 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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