ABOUT THIS PART
Solid PTFE tri clamp gasket, FDA compliant, in 2, 4 and 6 inch, from $3.25. Every size is priced on this page.
SPECIFICATIONS
| Material | Solid PTFE, FDA compliant |
|---|---|
| Connection | Tri-clamp sanitary |
| Sizes | 2 in, 4 in, 6 in |
| Prices | 2 in $3.25, 4 in $6.95, 6 in $19.95 |
| Smaller sizes | Solid PTFE is not stocked in 1 in or 1.5 in. Use the PTFE envelope gasket or the Viton gasket for those two sizes |
| Temperature range | -350 F to 500 F (-212 C to 260 C) |
| Solvent compatibility | Excellent on butane, propane, ethanol, heptane, pentane, hexane and isopropyl |
| Clamp torque | 50 in-lb, rigid gasket |
| Behavior | Rigid. Subject to creep and cold flow. Does not spring back |
| Clamp recommendation | Use with a high pressure clamp |
| Minimum solvent temperature, N.B. Oler system | -40 F (-40 C) on standard elastomeric gaskets, -65 F (-54 C) with PTFE. 3P Certz, confirmed September 2026 |
| Cold-side limit | PTFE is the gasket that takes an N.B. Oler system to its -65 F (-54 C) minimum solvent temperature. The material itself is rated to -350 F (-212 C) |
| What we recommend | Viton as the default on a hydrocarbon system, and it is what we run in our own shop. The PTFE envelope gasket with a Viton filler, also sold as PTFE encapsulated Viton, is the best overall choice, because it adds spring-back that solid PTFE does not have |
| Alternative | For joints broken every run, use the PTFE envelope gasket, which has a Viton core for recovery |
| Service interval | Every 3 to 6 months |
| Quantity, 20 LB system | 22 six inch gaskets |
| Quantity, 40 LB system | 44 six inch gaskets |
| Built or stocked | Stocked in Bend, usually ships the same day |
PTFE is the only material in this range that rates excellent against isopropyl, and it is the cheapest way to get full chemical resistance. It also runs to -350 F (-212 C), far colder than any elastomer, which matters more than most people expect.
Sizes and price
| Size | Price |
|---|---|
| 2 in | $3.25 |
| 4 in | $6.95 |
| 6 in | $19.95 |
Solid PTFE is stocked in 2, 4 and 6 inch only. For 1 inch or 1.5 inch, use the PTFE envelope gasket, which puts the same PTFE against the process with a Viton core behind it, or the Viton gasket if the service is not isopropyl and not below -40 F (-40 C).
The numbers
- Temperature: -350 F to 500 F (-212 C to 260 C)
- Clamp torque: 50 in-lb, the rigid figure. An elastomeric gasket takes 30. Torque a rigid gasket to elastomeric spec and it leaks
- Compliance: FDA compliant
- Excellent on: butane, propane, ethanol, heptane, pentane, hexane and isopropyl
- Behavior: rigid. It does not spring back, it is subject to creep and cold flow, and it wants a high pressure clamp
If the joint gets broken and remade every run, the PTFE envelope gasket is the better choice. The Viton core inside gives it the recovery that solid PTFE does not have.
Solvent compatibility, by material
| Material | Butane | Propane | Ethanol | Heptane | Pentane | Hexane | Isopropyl |
|---|---|---|---|---|---|---|---|
| PTFE | A | A | A | A | A | A | A |
| Viton (FKM) | A | A | A | A | A | A | D |
| Buna-N | A | A | C | A | E | A | D |
| Silicone | D | D | B | D | D | D | D |
A excellent, B good with minor effect, C fair and not for continuous use, D severe and not recommended, E no data. From the N.B. Oler Sintered Filter Technical Specifications, Rev. 2026.1.
Which material for which job
| Material | Temperature | Torque | Pick it when |
|---|---|---|---|
| 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 | PTFE chemistry with spring-back, for joints broken every run |
| 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 |
| 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
- 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.
| STOCKED, NOT BUILT | Stocked by N.B. Oler and built by its manufacturer. |
|---|---|
| FITS | Any tri-clamp joint on a 10, 20 or 40 LB system where isopropyl is in service, or where the process runs colder than Viton's -40 F (-40 C) limit. Sizes are 2, 4 and 6 inch. It does not fit 1 inch or 1.5 inch joints, because solid PTFE is not stocked in those two sizes, so use the PTFE envelope gasket or the Viton gasket there. Best on joints that stay made up, because solid PTFE takes a set. For a joint broken and remade every run, use the PTFE envelope gasket. Torque to 50 in-lb, not the 30 in-lb an elastomeric gasket takes. |
▦ 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
When do I need PTFE instead of Viton?
Two cases. Isopropyl service, where Viton rates severe and PTFE rates excellent. And anything running colder than -40 F (-40 C), since PTFE holds to -350 F (-212 C) where Viton stops.
What sizes do you stock?
Solid PTFE comes in 2, 4 and 6 inch.
What do they cost?
2 in $3.25, 4 in $6.95 and 6 in $19.95.
Do you have a 1 inch or 1.5 inch solid PTFE gasket?
No, solid PTFE is stocked in 2, 4 and 6 inch only. For those two sizes use the PTFE envelope gasket, which gives you the same PTFE against the process with a Viton core behind it, or the Viton gasket if the service is not isopropyl and not below -40 F (-40 C).
Why is the torque different from Viton and Buna-N?
PTFE is rigid, so it takes 50 in-lb against 30 for an elastomeric gasket. Torquing a rigid gasket to elastomeric spec leaks. Torquing an elastomeric gasket to rigid spec destroys it.
Solid PTFE or the envelope gasket?
Solid PTFE is cheaper and right for a joint that stays made up. The envelope has a Viton core that gives it spring-back, so it reseals instead of taking a set, which is what you want on a joint broken every run.
What is creep and cold flow?
PTFE slowly deforms under sustained load. It is why the material wants a high pressure clamp and why the gasket needs replacing on interval rather than on appearance.
What temperature can PTFE take?
-350 F to 500 F, which is -212 C to 260 C.
How often should these be replaced?
Every 3 to 6 months regardless of appearance, and immediately on any cracking, tearing, splitting or permanent deformation.
How many does a system take?
A 20 LB system takes 22 six inch gaskets and a 40 LB takes 44.
Is it FDA compliant?
Yes.
Which gasket is the best overall?
The PTFE envelope gasket with a Viton filler, also sold as PTFE encapsulated Viton. It puts the same PTFE against the process, including isopropyl, and adds a Viton core that springs back so the joint reseals instead of taking a set. Solid PTFE is cheaper and is right for a joint that stays made up. Viton is the default on a hydrocarbon system and the one we run in our own shop, rated -40 F (-40 C), and -40 F and -40 C are the same temperature.