Flexible Graphite
Flexible Graphite is binder-free sheet rolled from acid-intercalated, thermally exfoliated natural graphite (the generic form of Grafoil), offered as FG-98 and FG-99N purity levels, low- and high-density FG-LD/FG-HD, oxidation-inhibited FG-OX and metal-laminated FG-SS.
Reference datasheet — Flexible Graphite is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the FG-98 condition
Flexible Graphite tempers and conditions
Flexible Graphite is supplied in 6 conditions, soft to hard. FG-98 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Low-density soft foil, 0.7 g/cm³ | Pick for very low seating stress, rough or warped flange faces and maximum conformability. | 4 | 3 | 110 W/m·K | ||
FG-98Default Standard grade, ≥98 % C, 1.0 g/cm³ foil/sheet | General industrial gasket, packing and heat-spreader stock; the default when no purity or reinforcement is specified. | 5 | 2 | 150 W/m·K | ||
High-purity / nuclear grade, ≥99.5 % C, low S & Cl | Use for austenitic stainless and nuclear service where leachable chloride/sulfur must be limited to avoid stress-corrosion cracking. | 5 | 2 | 160 W/m·K | ||
Oxidation-inhibited grade | Choose for hot-air or cycling service above 500 °C where untreated foil would burn back at the gasket OD. | 5 | 1.8 | 130 W/m·K | ||
High-density die-formed grade, 1.6–1.8 g/cm³ | Die-formed valve packing rings and high-pressure seals where low permeability and extrusion resistance matter. | 8 | 1.5 | 190 W/m·K | ||
316L stainless foil / tanged-insert reinforced laminate | Standard choice for cut flange gaskets: the metal core carries handling and blow-out loads that plain foil cannot. | 18 | 3 | 100 W/m·K |
What is Flexible Graphite?
Flexible Graphite is binder-free sheet rolled from acid-intercalated, thermally exfoliated natural graphite (the generic form of Grafoil), offered as FG-98 and FG-99N purity levels, low- and high-density FG-LD/FG-HD, oxidation-inhibited FG-OX and metal-laminated FG-SS. Its compressibility and conformability at about 1.0 g/cm³, 150 W/m·K conductivity and broad chemical resistance (corrosion score 90) make it the standard material for gaskets, packing and thermal interface pads. Tensile strength is only 5 MPa, so sheet needs a metal insert or eyelet for handling and blow-out resistance, and unprotected material oxidizes in air above about 450 °C. Flexible Graphite has a density of 1 g/cm³ (0.0361 lb/in³), lighter than 98% of ceramic grades. It melts at 3,650°C (6,602 °F). Flexible Graphite has a tensile strength of 5 MPa (0.725 ksi), weaker than 97% of ceramic grades. Elongation at break is 2% and the elastic modulus is 2 GPa (0.29 Msi).
What is Flexible Graphite used for?
- gaskets
- packing rings
- thermal interface pads
- fire-safe seals
Advantages
- Ductile — tolerates forming and impact — 2%, better than 99% of ceramic grades
- Lightweight — 1 g/cm³ (0.0361 lb/in³), better than 98% of ceramic grades
- Easy to machine — 90/100, better than 94% of ceramic grades
- Conducts heat well — 150 W/m·K (86.7 BTU/hr·ft·°F), better than 93% of ceramic grades
- Good corrosion resistance — 90/100, better than 81% of ceramic grades
Limitations
- Low stiffness — 2 GPa (0.29 Msi), worse than 98% of ceramic grades
- Limited service temperature — 450°C (842 °F), worse than 77% of ceramic grades
Flexible Graphite properties
Typical room-temperature values for Flexible Graphite-FG-98; bars are the position among ceramic grades.
Physical3
Flexible Graphite has a density of 1 g/cm³ (0.0361 lb/in³), lighter than 98% of ceramic grades. It melts at 3,650°C (6,602 °F).
Mechanical7
Flexible Graphite has a tensile strength of 5 MPa (0.725 ksi), weaker than 97% of ceramic grades. Elongation at break is 2% and the elastic modulus is 2 GPa (0.29 Msi).
Thermal5
Flexible Graphite is rated for continuous service to 450°C (842 °F). It conducts heat at 150 W/m·K (86.7 BTU/hr·ft·°F), better than 93% of ceramic grades. Thermal expansion is 1 µm/m·K (0.556 µin/in·°F).
Electrical2
Flexible Graphite has an electrical resistivity of 1×10⁻⁵ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (90/100), better than 81% of ceramic grades.
Sustainability4
Producing a kilogram of Flexible Graphite takes about 60 MJ of energy and emits 5 kg of CO₂ — less than 76% of ceramic grades. Typical recycled content is 5%.
Manufacturability1
Flexible Graphite's machinability is excellent (90/100, better than 94% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. Flexible Graphite is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Flexible Graphite
Is Flexible Graphite easy to machine?
Cut by steel-rule die, knife plotter, waterjet or laser; no coolant needed but capture the conductive dust — it shorts electronics and clogs filters.
Can Flexible Graphite be welded?
Not weldable; joints are made by overlapping/skiving foil or by mechanically crimping to a metal insert, never by adhesive at high temperature.
Can Flexible Graphite be formed, bent or molded?
Calendered from exfoliated worms to thickness, then laminated to metal foil or die-compressed into rings/packing at 1.6–1.9 g/cm³ without binder.
Flexible Graphite chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| ashresidual mineral ash | 0.1 – 2 | 1 |
| S≤1200 ppm standard, ≤300 ppm nuclear grade | ≤ 0.12 | 0.05 |
| Cl≤50 ppm; ≤25 ppm leachable for nuclear grade | ≤ 0.01 | 0 |
| moisture | ≤ 0.5 | 0.2 |
| Ccarbon content; 99.5 % min for high-purity/nuclear grade | ≥ 98 (balance) |
What surface finishes work on Flexible Graphite?
Normally used as-rolled; optional anti-stick (PTFE/graphite release) coating or phosphate oxidation-inhibitor impregnation, and edge sealing for high-velocity flow.
How much does Flexible Graphite cost?
Flexible Graphite is a premium-cost ceramic ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Flexible Graphite — frequently asked
What is Flexible Graphite used for?
Flexible Graphite is typically used for gaskets, packing rings, thermal interface pads and fire-safe seals. In short: most conformable graphite form; binder-free sealing sheet; very low tensile strength.
What is the tensile strength of Flexible Graphite?
Flexible Graphite has a typical tensile strength of 5 MPa (0.725 ksi) — weaker than 97% of ceramic grades. Strength varies by condition: see the 6 listed tempers.
Is Flexible Graphite easy to machine?
Yes — machinability is rated excellent (90/100, better than 94% of ceramic grades). Cut by steel-rule die, knife plotter, waterjet or laser; no coolant needed but capture the conductive dust — it shorts electronics and clogs filters.
Can Flexible Graphite be welded?
Not weldable; joints are made by overlapping/skiving foil or by mechanically crimping to a metal insert, never by adhesive at high temperature.
What surface finishes work on Flexible Graphite?
Normally used as-rolled; optional anti-stick (PTFE/graphite release) coating or phosphate oxidation-inhibitor impregnation, and edge sealing for high-velocity flow.
Can Flexible Graphite be formed, bent or molded?
Calendered from exfoliated worms to thickness, then laminated to metal foil or die-compressed into rings/packing at 1.6–1.9 g/cm³ without binder.
What is the maximum service temperature of Flexible Graphite?
Flexible Graphite is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Flexible Graphite cost?
Flexible Graphite is a premium-cost ceramic ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- DIN 28090-2 / DIN 28091-4 — Gaskets from graphite sheet, characteristics and testing — DIN (2014)
- ASTM F2168 — Standard Specification for Packing Material, Graphitic, Corrugated Ribbon or Textured Tape — ASTM (2018)
- Flexible graphite foil and reinforced sheet datasheets (GrafTech Grafoil, SGL Sigraflex, Mersen Papyex) — producers (2023)
- ASM Engineered Materials Handbook — Carbon and Graphite — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.