Tri-Clamp Buna-N Gasket (Nitrile Rubber)
ABOUT THIS PART
Buna-N nitrile tri clamp gasket, FDA compliant and 3-A approved, in 1, 1.5, 2, 3, 4, 6 and 10 inch, from $1.15. Every size is priced on this page.
Buna-N is the right gasket for water, food and general sanitary duty, and the cheapest in the range. For hydrocarbon extraction it is not the one to reach for.
Sizes and price
| Size | Price |
|---|---|
| 1 in | $1.25 |
| 1.5 in | $1.15 |
| 2 in | $2.50 |
| 3 in | $3.25 |
| 4 in | $5.50 |
| 6 in | $13.50 |
| 10 in | $22.00 |
The numbers
- Temperature: -30 F to 250 F (-34 C to 121 C), the narrowest range of any gasket on this site
- Clamp torque: 30 in-lb, the elastomeric figure. PTFE takes 50
- Compliance: FDA compliant, 3-A approved
- Excellent on: butane, propane, heptane, hexane
- Fair on ethanol, not for continuous use. Severe on isopropyl. No published data on pentane
Which material for which job
| Material | Temperature | Torque | Pick it when |
|---|---|---|---|
| Buna-N | -30 F to 250 F (-34 C to 121 C) | 30 in-lb | Water, food, general sanitary. Cheapest |
| Viton (FKM) | -40 F to 400 F (-40 C to 204 C) | 30 in-lb | The hydrocarbon default. Not for isopropyl |
| PTFE envelope, Viton core | -100 F to 400 F (-73 C to 204 C) | 50 in-lb | Isopropyl, or a joint broken every run |
Buna-N will physically fit any tri-clamp joint on a 10, 20 or 40 LB system. Viton rates excellent on everything Buna-N does not, which is why it is the material we run on solvent.
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. Buna-N stops at -30 F (-34 C), which is short of both, so on the cold end the gasket is the limiting component rather than the vessel. Check the gasket against your lowest process temperature rather than against the vessel rating.
What we recommend
- First choice for most buyers: the PTFE envelope gasket with a Viton filler, also sold as PTFE encapsulated Viton. PTFE chemistry against the process, including isopropyl, with a Viton core that springs back so the joint reseals instead of taking a set. It is the best overall gasket on this site.
- Default on a hydrocarbon system: Viton, rated -40 F to 400 F (-40 C to 204 C). Note that -40 F and -40 C are the same temperature, which is why both units read -40.
- Viton is 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, and the published rating is still -40 F (-40 C).
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
Buna-N or Viton for extraction?
Viton. Buna-N rates only fair on ethanol, severe on isopropyl, and has no published data on pentane. Viton rates excellent on all the hydrocarbons you run. Buna-N is cheaper and is the right call for water, food and general sanitary duty.
How often should tri-clamp gaskets be replaced?
Every 3 to 6 months in normal service. A gasket that has taken a compression set passes a leak check cold and then weeps once the line comes up to pressure, which is why interval beats inspection.
How many does a system take?
A 20 LB system takes 22 six inch gaskets and a 40 LB takes 44.
What temperature can Buna-N take?
-30 F to 250 F, which is -34 C to 121 C. That is the narrowest range of any gasket on this site.
Is Buna-N cold enough for my system?
Not quite. Minimum solvent temperature on an N.B. Oler system is -40 F (-40 C) on standard elastomeric gaskets, and Buna-N stops at -30 F (-34 C), so it is short by 10 F. Use Viton, which is rated to -40 F (-40 C) and is what we run in our own shop, or the PTFE envelope gasket with a Viton filler for the coldest work.
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. Viton is the default on a hydrocarbon system and the one we run, and Buna-N is for water, food and general sanitary duty.
What torque?
30 in-lb, the elastomeric figure. PTFE takes 50. Torquing an elastomeric gasket to the rigid spec crushes it.
Is it food safe?
Yes, FDA compliant and 3-A approved.
What sizes do you carry?
1, 1.5, 2, 3, 4, 6 and 10 inch, every size priced on this page.