Tri-Clamp Viton Gasket (FKM Fluoroelastomer)
ABOUT THIS PART
Viton (FKM) fluoroelastomer tri clamp gasket, FDA compliant, USP Class VI and 3-A, in 1, 1.5, 2, 4, 6 and 10 inch, from $2.75. Every size is priced on this page. No quote request.
Viton is the default gasket on a hydrocarbon system and it is what we run in our own shop. Against butane, propane, ethanol, heptane, pentane and hexane it rates excellent. Against isopropyl it rates severe, and that one case is what the PTFE envelope is for.
Sizes and price
| Size | Price |
|---|---|
| 1 in | $2.95 |
| 1.5 in | $2.75 |
| 2 in | $5.75 |
| 4 in | $14.95 |
| 6 in | $36.50 |
| 10 in | $56.00 |
We price these as competitively as we can against what the same gasket sells for elsewhere. These are standing prices, not a promotion.
The 1 inch costs more than the 1.5 inch because that is how it is priced upstream. There is no 3 inch in Viton. The Buna-N line has one.
The numbers
- Temperature: -40 F to 400 F (-40 C to 204 C) continuous, to 600 F (316 C) intermittent
- Clamp torque: 30 in-lb, the elastomeric figure. PTFE takes 50. Torque an elastomeric gasket to the rigid spec and you crush it
- Compliance: FDA, USP Class VI, 3-A
- Excellent on: butane, propane, ethanol, heptane, pentane, hexane
- Do not use on: isopropyl
Which material for which job
| Material | Temperature | Torque | Pick it when |
|---|---|---|---|
| Viton (FKM) | -40 F to 400 F (-40 C to 204 C) | 30 in-lb | The hydrocarbon default. Not for isopropyl |
| Buna-N | -30 F to 250 F (-34 C to 121 C) | 30 in-lb | Water, food, general sanitary. Cheapest |
| Solid PTFE | -350 F to 500 F (-212 C to 260 C) | 50 in-lb | Isopropyl, or cold service. Cheapest route to full chemical resistance |
| PTFE envelope, Viton core | -100 F to 400 F (-73 C to 204 C) | 50 in-lb | Isopropyl, or a joint broken every run |
| Silicone | -85 F to 450 F (-65 C to 232 C) | 30 in-lb | Steam and food. Severe on every hydrocarbon |
The cold end, and what actually limits it
Minimum solvent temperature on an N.B. Oler system is -40 F (-40 C) on standard elastomeric gaskets, and -65 F (-54 C) with PTFE. Both figures come from 3P Certz and were confirmed in September 2026. On the cold end of a run the gasket is the limiting component, not the vessel, so check the gasket against your lowest process temperature rather than against the vessel rating.
What we recommend
- Viton is the default on a hydrocarbon system, and it is what we run in our own shop. Rated -40 F to 400 F (-40 C to 204 C), which covers the working range of an N.B. Oler system. Note that -40 F and -40 C are the same temperature, which is why both units read -40.
- In our own operating experience Viton gives the best results in cold service of the elastomers we have used. That is shop experience rather than a laboratory result, and the published rating is still -40 F (-40 C).
- Step up for the coldest work or for isopropyl: the PTFE envelope gasket with a Viton filler, also sold as PTFE encapsulated Viton. PTFE chemistry against the process with a Viton core that springs back, and it is the best overall gasket on this site.
Replacement and quantities
- Replace every 3 to 6 months regardless of how it looks
- Replace immediately on any cracking, tearing, splitting or permanent deformation
- A gasket that has taken a compression set passes a cold leak check and then weeps once the line comes up to pressure. That is why interval beats inspection on a gasket
- A 20 LB system takes 22 six inch gaskets. A 40 LB takes 44
- Full comparison: Choosing the right gasket material for tri-clamp connections
Stocked in Bend, Oregon, and it usually ships the same day.
SPECIFICATIONS
▦ IN YOUR MANUAL
This part appears in the operator manual that ships with your system. The QR code there links to this page.
◈ REFERENCE FOR THIS PART
COMMON QUESTIONS
Viton or Buna-N for extraction?
Viton. Buna-N rates only fair on ethanol and has no published data on pentane, where Viton rates excellent on both. Buna-N is cheaper and is the right call for water, food and general sanitary duty.
Why can I not use Viton on isopropyl?
Viton rates severe against isopropyl. PTFE rates excellent and is the correct choice for that service.
What do they cost?
1 in $2.95, 1.5 in $2.75, 2 in $5.75, 4 in $14.95, 6 in $36.50 and 10 in $56.00. Those are standing prices, set as competitively as we can against what the same gasket sells for elsewhere, not a promotion.
What torque should I use?
30 in-lb. That is the elastomeric figure. PTFE takes 50. Torquing an elastomeric gasket to the rigid spec crushes it.
How often should these be replaced?
Every 3 to 6 months regardless of appearance, and immediately on any cracking, tearing, splitting or permanent deformation. A gasket that has taken a compression set passes a cold leak check and then weeps under pressure.
What temperature can Viton take?
-40 F to 400 F, which is -40 C to 204 C, continuous, and to 600 F (316 C) intermittent.
Is Viton cold enough for my system?
Yes, for the working range. Minimum solvent temperature on an N.B. Oler system is -40 F (-40 C) on standard elastomeric gaskets, and Viton is rated to exactly that. -40 F and -40 C are the same temperature, which is why both units read -40. Viton is also what we run in our own shop, and in our own operating experience it gives the best results in cold service of the elastomers we have used. That is shop experience rather than a laboratory result. For the coldest work, or for isopropyl, step up to the PTFE envelope gasket with a Viton filler, also called PTFE encapsulated Viton.
Which gasket is the best overall?
The PTFE envelope gasket with a Viton filler, also sold as PTFE encapsulated Viton. You get PTFE chemistry against the process, including isopropyl, and a Viton core that springs back so the joint reseals instead of taking a set. Viton remains the default and the one we run, and the envelope is the step up.
How many does a system take?
A 20 LB takes 22 six inch gaskets, a 40 LB takes 44.
Do you have a 3 inch Viton gasket?
No. The Viton line runs 1, 1.5, 2, 4, 6 and 10 inch. The Buna-N line carries a 3 inch.
Why is the 1 inch more than the 1.5 inch?
Because that is how it is priced upstream. The 1 inch costs more to buy than the 1.5 inch, and the page reflects that rather than smoothing it over.