Dairy and Tri-Clamp Gasket Materials: EPDM vs Silicone vs PTFE vs Viton
The gasket is the cheapest part of a sanitary connection and the one that fails first. Get the material wrong and it does not just leak — it degrades into the product, fails a CIP cycle, or hardens and cracks in a way that seeds a contamination point.
Most gasket failures are material-selection failures: the wrong elastomer for the temperature, the cleaning chemistry, or the product. This guide covers the sanitary gasket materials used in dairy and tri-clamp lines, compared on the three things that actually decide the choice. Asiad Steel Industries supplies dairy and TC gaskets alongside the full hygienic range from Pune.
What Is a Sanitary Gasket?
A sanitary gasket is a food-grade elastomer or fluoropolymer seal placed between two tri-clamp ferrule faces and compressed by a clamp to form a leak-proof, crevice-free connection. Common materials are EPDM, silicone, PTFE, Viton (FKM) and Buna-N (NBR), each with a distinct temperature range and chemical resistance.
The gasket is sized to the ferrule flange OD, not the tube OD — the same sizing logic as the ferrule itself. See our dairy gasket and TC gasket ranges.
The Five Sanitary Gasket Materials
Three factors decide every gasket choice: temperature range, chemical/CIP resistance, and product compatibility.
EPDM — the dairy default
- Temperature: roughly -48°C to +135°C
- Strengths: excellent with hot water, steam and caustic CIP; the standard for dairy and general food lines
- Weakness: zero oil and fat resistance — breaks down on fatty products
- Compliance: FDA food-grade formulations available
Silicone — widest temperature range
- Temperature: roughly -50°C to +230°C
- Strengths: the widest temperature range of the common elastomers; very flexible; FDA and USP Class VI formulations available
- Weakness: lower mechanical strength and tear resistance; not ideal for high-pressure clamping
- Best for: high-temperature service, pharmaceutical work, sight-glass seals
PTFE — chemical inertness
- Temperature: very wide; effectively inert
- Strengths: resists virtually all chemicals; used where elastomers degrade; envelope gaskets (PTFE over an EPDM core) combine inertness with elastomer memory
- Weakness: hard, poor recovery/”cold flow” — pure PTFE creeps under load and needs re-torquing
- Best for: aggressive chemicals, rotating fittings, high-purity service
Viton (FKM) — oils and aggressive chemistry
- Temperature: roughly -15°C to +200°C+
- Strengths: best resistance to oils, fats and aggressive chemicals; long service life on hot caustic CIP
- Weakness: poor cold flexibility; higher cost
- Best for: fatty products, CIP return lines running hot caustic
Buna-N (NBR) — economical, limited
- Temperature: roughly -40°C to +107°C
- Strengths: low cost, good with oils and fats
- Weakness: poor with acids, caustics and hot CIP; degrades under UV; does not pass USP Class VI
- Best for: low-cost, low-temperature, non-caustic duty only
Comparison Table
| Material | Temp range (approx.) | CIP / caustic | Oils & fats | Food/pharma compliance | Relative cost |
|---|---|---|---|---|---|
| EPDM | -48 to +135°C | Excellent | Poor | FDA grades | Low |
| Silicone | -50 to +230°C | Good | Fair | FDA, USP VI grades | Medium |
| PTFE | Very wide | Excellent | Excellent | FDA, USP VI | Higher |
| Viton (FKM) | -15 to +200°C+ | Excellent | Excellent | FDA grades | High |
| Buna-N | -40 to +107°C | Poor | Good | Limited | Lowest |
The Most Common Gasket Failure
Running Buna-N against hot caustic CIP. Hot caustic at 70–80°C degrades nitrile rapidly, causing leaks and a contamination risk. If a line runs hot caustic cleaning, specify EPDM, Viton or PTFE — not Buna.
The second most common: reusing gaskets. Sanitary gaskets are single-use items. A gasket that looks fine after removal has taken a compression set and will not reseal reliably. In pharmaceutical service, reuse is never acceptable; in food service, only under a validated SOP. Budget for replacement.
Gasket Thickness and Fit
- Size to the ferrule OD, not the tube OD — a 1″ and 1.5″ ferrule share a gasket size
- Match gasket ID close to tube ID to minimise the dead zone at the joint, which is where product accumulates
- A protruding or undersized gasket is a bacterial trap — the flush internal profile is the entire point of a hygienic connection
- PTFE needs re-torquing after initial installation because it cold-flows
For the joint-level detail, see our dairy fittings installation best practices and what dairy fittings are, types and uses.
Conclusion
Sanitary gasket selection comes down to three questions: how hot, what cleaning chemistry, and what product. EPDM is the dairy default and handles caustic CIP but not fats; silicone gives the widest temperature range; PTFE is inert but cold-flows; Viton handles oils and hot caustic at a price; Buna is cheap but wrong for hot caustic. Size to the ferrule OD, match the ID to the tube, and replace rather than reuse.
Asiad Steel Industries supplies FDA-compliant dairy and tri-clamp gaskets in EPDM, silicone, PTFE, Viton and Buna from Pune, sized to standard ferrule ODs.
Not sure which gasket? Tell us your temperature, CIP chemistry and product and our team will recommend the material.
View dairy gaskets | TC gaskets | Request a quotation
FAQs
Which gasket material is best for dairy processing?
EPDM is the default for dairy because it withstands the hot water, steam and caustic used in CIP cleaning, and food-grade formulations are widely available. For fatty products it performs poorly and Viton (FKM) or PTFE is preferred, and for the widest temperature range or pharmaceutical work, silicone is often specified.
What is the difference between EPDM and silicone sanitary gaskets?
EPDM handles hot caustic CIP well and is the dairy standard, with a temperature range of roughly -48°C to +135°C, but it has no oil resistance. Silicone offers a wider temperature range of roughly -50°C to +230°C and is very flexible, making it suitable for high-temperature and pharmaceutical service, but it has lower mechanical strength.
Can I reuse a tri-clamp gasket?
No, not reliably. Sanitary gaskets take a compression set when clamped and will not reseal dependably once removed, even if they look intact. Reuse is never acceptable in pharmaceutical service and only permitted in food service under a validated procedure. Gaskets should be treated as single-use consumables.
What gasket should I avoid with hot caustic CIP?
Avoid Buna-N (NBR). Hot caustic cleaning degrades nitrile rapidly, causing leaks and contamination risk — this is the most common sanitary gasket failure. For hot caustic CIP lines, specify EPDM, Viton (FKM) or PTFE instead.
How do I choose tri-clamp gasket thickness and size?
Size the gasket by the ferrule flange outside diameter, not the tube diameter, since several tube sizes share a ferrule OD. Match the gasket inner diameter as closely as practical to the tube inner diameter to minimise the dead zone at the joint. A protruding or undersized gasket creates a bacterial trap that defeats the purpose of a hygienic connection.
