FEPM LT
Grade
also Aflas
LT = low-temperature TFE/P/VDF terpolymer grade
Pick when sealing below −10 °C: the TFE/P/VDF terpolymer lowers Tg to −22 °C, but resistance to strong alkalis and amines drops and service is capped at 200 °C.
Values for the LT condition
Other FEPM grades and fills
FEPM is listed in 7 conditions; see the grade overview at FEPM.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Shore A 60 | Pick for low-pressure, low-clamp-force joints or rough sealing faces needing better conformability; the softer compound reaches 320 % elongation but resists extrusion less. | — | 13 | 320 | 15 Shore D |
LTThis page Low-temperature TFE/P/VDF terpolymer grade | Pick when sealing below −10 °C: the TFE/P/VDF terpolymer lowers Tg to −22 °C, but resistance to strong alkalis and amines drops and service is capped at 200 °C. | — | 15 | 260 | 22 Shore D |
Wire & cable insulation / jacket compound | Pick for electric submersible pump cables and high-temperature nuclear or chemical-plant cable jackets needing high insulation, steam resistance and flame retardancy to 200 °C. | — | 15 | 250 | 30 Shore D |
SHA70Default Shore A 70 | Use as the default general-purpose sealing hardness, balancing seal conformability against extrusion resistance, with 16 MPa tensile and service to 230 °C. | — | 16 | 250 | 22 Shore D |
Shore A 80 | Choose for medium- and high-pressure oil and gas seals and grooves with clearance gaps, trading elongation down to 200 % for higher extrusion resistance at 18 MPa tensile. | — | 18 | 200 | 30 Shore D |
Shore A 90 | Use for extreme-pressure or large-gap service and for back-up rings and seal support elements; 20 MPa tensile comes with elongation limited to 150 %. | — | 20 | 150 | 40 Shore D |
AED/RGD | Choose for high-pressure gas wells and CO₂/H₂S service with rapid depressurisation, qualified to NORSOK M-710 / ISO 23936-2; elongation is limited to 160 %. | — | 20 | 160 | 40 Shore D |
What is FEPM LT?
FEPM LT is FEPM in the LT grade — pick when sealing below −10 °C: the TFE/P/VDF terpolymer lowers Tg to −22 °C, but resistance to strong alkalis and amines drops and service is capped at 200 °C. FEPM LT has a tensile strength of 15 MPa (2.18 ksi), weaker than 74% of polymer grades. Elongation at break is 260% and the elastic modulus is 0.01 GPa (0.0012 Msi). FEPM LT has a density of 1.62 g/cm³ (0.0585 lb/in³), heavier than 94% of polymer grades. Its glass-transition temperature is -22°C (-8 °F). SHA70 is the default condition FabDigit quotes; LT is available on request or by drawing note.
Advantages
- Good UV / weathering resistance — 95/100, better than 95% of polymer grades
- High service temperature — 200°C (392 °F), better than 87% of polymer grades
- Ductile — tolerates forming and impact — 260%, better than 80% of polymer grades
Limitations
- Difficult to machine — 20/100, worse than 97% of polymer grades
- High mold shrinkage — 3%, worse than 97% of polymer grades
- High embodied carbon — 14 kg CO₂/kg, worse than 95% of polymer grades
- Heavy — 1.62 g/cm³ (0.0585 lb/in³), worse than 94% of polymer grades
- Low stiffness — 0.01 GPa (0.0012 Msi), worse than 82% of polymer grades
FEPM LT properties
Typical room-temperature values for FEPM LT; 19 are specific to this condition. Other listed values are FEPM reference data and may not represent this condition. Bars are the position among polymer grades.
Physical3
FEPM LT has a density of 1.62 g/cm³ (0.0585 lb/in³), heavier than 94% of polymer grades. Its glass-transition temperature is -22°C (-8 °F).
Mechanical8
FEPM LT has a tensile strength of 15 MPa (2.18 ksi), weaker than 74% of polymer grades. Elongation at break is 260% and the elastic modulus is 0.01 GPa (0.0012 Msi).
Thermal8
FEPM LT is rated for continuous service to 200°C (392 °F). It conducts heat at 0.22 W/m·K (0.127 BTU/hr·ft·°F), better than 60% of polymer grades. Thermal expansion is 200 µm/m·K (111.1 µin/in·°F).
Electrical5
FEPM LT is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 74% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of FEPM LT takes about 290 MJ of energy and emits 14 kg of CO₂ — more than 95% of polymer grades. Typical recycled content is 0%.
Manufacturability4
FEPM LT's machinability is poor (20/100, worse than 97% of polymer grades); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with FEPM LT
Is FEPM easy to machine?
After cure, work is limited to waterjet cutting, die cutting or low-temperature turning; the material is soft and highly resilient, so use sharp tooling, cryogenic support and generous tolerances.
Can FEPM be welded?
Not weldable; joints are spliced with uncured tape and heat-vulcanized, or bonded with fluoroelastomer-specific adhesive, and joint strength is below that of the parent rubber.
Can FEPM be formed, bent or molded?
Compression, transfer or injection mold with a peroxide press cure at 170-180 °C, followed by a mandatory post-cure of 4-16 h at 200-250 °C to lower compression set and drive off volatiles. Mooney viscosity is high, so mix thoroughly and vent the mold.
What surface finishes work on FEPM?
Cryogenic deflashing (freeze tumbling or blasting) is the normal route; PTFE or graphite coatings and plasma treatment can reduce friction. Do not clean with ketone or ester solvents, which swell the compound.
FEPM 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 |
|---|---|---|
| tetrafluoroethylene (TFE)near-alternating with propylene; ~54–57 wt% F in polymer | 65 – 75 | 70 |
| vinylidene fluoride (VDF)present only in low-temperature terpolymer grades | 0 – 20 | 0 |
| carbon black (filler)phr in compound; mineral filler used in white/food grades | 0 – 30 | 20 |
| organic peroxide + TAIC coagentperoxide cure system (phr) | 1 – 5 | 3 |
| propylenecomonomer | ≥ 25 (balance) | — |
FEPM LT — frequently asked
What is FEPM LT used for?
FEPM LT is typically used for oilfield downhole seals exposed to amines/H2S, steam and chemical process seals, automotive powertrain seals and semiconductor process seals. In short: base- and steam-resistant fluoroelastomer; 230 °C amine/H2S service; outlasts FKM in caustics.
What is the tensile strength of FEPM LT?
FEPM LT has a typical tensile strength of 15 MPa (2.18 ksi) — weaker than 74% of polymer grades. Strength varies by condition: see the 7 listed tempers.
Is FEPM LT easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of polymer grades). After cure, work is limited to waterjet cutting, die cutting or low-temperature turning; the material is soft and highly resilient, so use sharp tooling, cryogenic support and generous tolerances.
Can FEPM LT be welded?
Not weldable; joints are spliced with uncured tape and heat-vulcanized, or bonded with fluoroelastomer-specific adhesive, and joint strength is below that of the parent rubber.
What surface finishes work on FEPM LT?
Cryogenic deflashing (freeze tumbling or blasting) is the normal route; PTFE or graphite coatings and plasma treatment can reduce friction. Do not clean with ketone or ester solvents, which swell the compound.
Can FEPM LT be formed, bent or molded?
Compression, transfer or injection mold with a peroxide press cure at 170-180 °C, followed by a mandatory post-cure of 4-16 h at 200-250 °C to lower compression set and drive off volatiles. Mooney viscosity is high, so mix thoroughly and vent the mold.
What is the maximum service temperature of FEPM LT?
FEPM LT is rated for continuous use to about 200°C (392 °F), and briefly to 260°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Aflas TFE/Propylene Fluoroelastomer — AGC Chemicals (2022)
- ASTM D1418 — Rubber and Rubber Latices Nomenclature (FEPM) — ASTM (2022)
- ASTM D2000 — Classification System for Rubber Products in Automotive Applications — ASTM (2020)
- NORSOK M-710 / ISO 23936-2 — Standards Norway / ISO (2020)
- Fluoroelastomers Handbook — The Definitive User's Guide — Elsevier/William Andrew (2016)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.