# Tri-clamp flat gasket (hot joint, bore ID): 1.7 mm ring, ½ to 4 in

> What flat gasket goes in a hot tri-clamp joint?

- Category: Stirling engines › Tri-clamp engine parts
- Kind: Hardware
- Basis: Flat ring: OD = C3 − 1 (flange less 0.5 per side), ID = tube bore, 1.7 mm thick (the ISO 2852 Type B web, the gap the clamp groove is drawn for)
- Page: https://xemstudio.com/objects/tri-clamp-hot-gasket/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-hot-gasket · Plain text: https://xemstudio.com/objects/tri-clamp-hot-gasket/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- A flat 1.7 mm ring that takes the place of the Type B gasket at a joint that runs too hot for an elastomer gasket, such as the flame end of a Stirling engine, or wherever a piston or displacer has to pass through the joint (its ID is the bore, so there is no lip in the way).
- OD is the flange diameter less 1 mm (Ø24.0 / 49.5 / 63.0 / 76.5 / 90.0 / 118.0); ID is the bore of the larger tube on that flange (Ø15.75 / 34.8 / 47.5 / 60.2 / 72.9 / 97.38).
- Thickness 1.7 mm is the Type B gasket's web, so the clamp's groove meets the rims after the same 0.4 mm of travel as at a Type B joint and the last 0.6 mm per half squeezes the ring (designed); a thinner ring would leave the clamp unable to reach the rims.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| hot-gasket ring | C3 − 1 × bore × 1.7 (the Type B web) | ferrule faces; the clamp squeezes it in its last 0.6 mm | designed | hot-gasket-* |

## Sizes

| size_in | od_mm | id_mm | thickness_mm |
|---|---|---|---|
| ½–¾ | 24.0 | 15.75 | 1.7 |
| 1–1½ | 49.5 | 34.8 | 1.7 |
| 2 | 63.0 | 47.5 | 1.7 |
| 2½ | 76.5 | 60.2 | 1.7 |
| 3 | 90.0 | 72.9 | 1.7 |
| 4 | 118.0 | 97.38 | 1.7 |

## Where the files are

- ISO: [ISO 2852:1993 Stainless steel clamp pipe couplings for the food industry](https://www.iso.org/standard/7873.html) — standard — ISO (verify at link)
- Long Earth Society: [Tri-clamp Stirling engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (6 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-hot-gasket/index.json

- hot-gasket-0.75in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-0.75in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-0.75in.stl) — 0.75 in flat gasket: Ø24 OD × Ø15.8 ID (= the bore) × 1.7 (the Type B web), sits flat on the lands in place of the Type B gasket at a flame-side joint or wherever a piston or displacer must pass the joint
- hot-gasket-1.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-1.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-1.5in.stl) — 1.5 in flat gasket: Ø49.5 OD × Ø34.8 ID (= the bore) × 1.7 (the Type B web), sits flat on the lands in place of the Type B gasket at a flame-side joint or wherever a piston or displacer must pass the joint
- hot-gasket-2in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-2in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-2in.stl) — 2 in flat gasket: Ø63 OD × Ø47.5 ID (= the bore) × 1.7 (the Type B web), sits flat on the lands in place of the Type B gasket at a flame-side joint or wherever a piston or displacer must pass the joint
- hot-gasket-2.5in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-2.5in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-2.5in.stl) — 2.5 in flat gasket: Ø76.5 OD × Ø60.2 ID (= the bore) × 1.7 (the Type B web), sits flat on the lands in place of the Type B gasket at a flame-side joint or wherever a piston or displacer must pass the joint
- hot-gasket-3in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-3in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-3in.stl) — 3 in flat gasket: Ø90 OD × Ø72.9 ID (= the bore) × 1.7 (the Type B web), sits flat on the lands in place of the Type B gasket at a flame-side joint or wherever a piston or displacer must pass the joint
- hot-gasket-4in: [STEP](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-4in.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-clamps/hot-gasket-4in.stl) — 4 in flat gasket: Ø118 OD × Ø97.4 ID (= the bore) × 1.7 (the Type B web), sits flat on the lands in place of the Type B gasket at a flame-side joint or wherever a piston or displacer must pass the joint

## How it fits

### Goes in or on
- [Tri-clamp (Tri-Clover) sanitary ferrule, 1/2 to 4 inch](https://xemstudio.com/objects/tri-clamp-ferrule/): on the lands between two faces

### Connects to
- [Tri-clamp clamp, two-bolt: every flange size ½ to 4 in](https://xemstudio.com/objects/tri-clamp-clamps/): the clamp squeezes it

### Alternatives
- [Tri-clamp gasket, ISO 2852 Type B: 1.5 and 2 in](https://xemstudio.com/objects/tri-clamp-gasket/): Type B elastomer gasket for cool joints

### Also needed
- [Tri-clamp heat shield washer: 0.6 mm, ½ to 4 in tube](https://xemstudio.com/objects/tri-clamp-heat-shield/): shield between the flame and the clamp

## Questions

**What size is a 2 inch flat hot gasket?**

Ø63.0 OD × Ø47.5 ID × 1.7 mm.

**Why a flat gasket at a hot joint?**

The Type B gasket is an elastomer with a bead in the face recesses and a lip into the bore; the flat ring has neither and sits on the lands, for a joint too hot for the elastomer or a joint a piston has to pass.

**Why is the flat gasket 1.7 mm thick?**

That is the Type B web thickness the two-bolt clamp's groove is drawn for: the groove reaches the rims after 0.4 mm and squeezes the ring in the last 0.6 mm of travel.

## Fits with

- [Tri-clamp clamp, two-bolt: every flange size ½ to 4 in](https://xemstudio.com/objects/tri-clamp-clamps/)
- [Tri-clamp gasket, ISO 2852 Type B: 1.5 and 2 in](https://xemstudio.com/objects/tri-clamp-gasket/)
- [Tri-clamp heat shield washer: 0.6 mm, ½ to 4 in tube](https://xemstudio.com/objects/tri-clamp-heat-shield/)
- [Sanitary clamp gaskets, ISO 2852 Type B: ½ to 4 in](https://xemstudio.com/objects/sanitary-clamp-gaskets/)
- [Tri-clamp (Tri-Clover) sanitary ferrule, 1/2 to 4 inch](https://xemstudio.com/objects/tri-clamp-ferrule/)