# Tri-clamp closed-end spool: 2 in × 152.4 mm (6 in) with a welded closed end, the hot end of a pressurised Stirling

> What is a closed-end tri-clamp spool and how do I order one for a Stirling hot end?

- Category: Hardware › Sanitary clamp fittings
- Kind: Hardware
- Basis: Fabrication spec: a standard 2 in ferrule (ISO 2852 face, as the ferrule on this site) on BPE 2 in tube Ø50.8 × 1.65, closed at the far end by a 3 mm welded end; plain outside (heat exchangers clamp on, see the fin sleeve)
- Page: https://xemstudio.com/objects/tri-clamp-closed-end-spool/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-closed-end-spool · Plain text: https://xemstudio.com/objects/tri-clamp-closed-end-spool/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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

- Drawing to send to a sanitary fabricator: '2 in × 152.4 mm closed-end spool, one 2 in clamp ferrule, tube Ø50.8 × 1.65, closed end 3 mm, 1.5 outside round'. The face is a standard 2 in clamp face; the rest is plain tube.
- On the free-piston generator it is the hot end: the burner fires at its closed end and lower half, and the only joint is at the top, at the regenerator's cold end, so no gasket is near the flame.
- Inside it are the displacer liner, the heater insert, the regenerator screens and the displacer's hot end. The bore is a slide fit for the liner's spokes and the inserts.
- At the generator's relief setting (15 bar gauge) the tube's hoop stress is 23.0 MPa; whether that is acceptable at the hot-end temperature depends on what the spool is made of, which is the builder's check.

## 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 |
|---|---|---|---|---|
| face | ISO 2852 2 in (land Ø56.5–Ø64, rim 2.85, 1.6 recess, 20° back) | high-pressure clamp + half gaskets round the liner rim | clamp | all |
| bore | Ø47.5 × 149.4 to the closed end | liner spokes, heater insert OD, regenerator ring ODs | slide | all |
| tube OD | Ø50.8 (z 2–68.5 and 76.5–82.5 from the closed end) | fin sleeve halves, shroud lids | clamp | all |

## Sizes

| feature | value |
|---|---|
| face | ISO 2852, 2 in (Ø64 flange, Ø56.5 groove, 1.6 recess) |
| tube | Ø50.8 × 1.65 (bore Ø47.5) |
| face to outer end | 152.4 |
| closed end | 3.0, 1.5 outer round |

## Where the files are

- ISO (via iTeh sample): [ISO 2852 clamp liners: face profile and flange / groove diameters](https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf) — PDF — standard excerpt; dimensions are facts
- ASME: [BPE Bioprocessing Equipment (tube OD and wall, clamp fittings)](https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment) — standard — ASME; dimensions are facts (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-closed-end-spool/index.json

- closed-spool-2in-152.4: [STEP](https://xemstudio.com/files/hardware/tri-clamp-closed-end-spool/closed-spool-2in-152.4.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-closed-end-spool/closed-spool-2in-152.4.stl) — 2 in × 152.4 mm closed-end spool: ISO 2852 ferrule face at the open end, Ø50.8 × 1.65 tube, 3 mm welded closed end with a 1.5 outer round; bore Ø47.5 to the closed end (149.4 deep)

## Questions

**Can I order this from a sanitary fabricator?**

Yes: it is a standard 2 in ferrule on standard tube with a welded closed end; the drawing and the one-line spec above are what they need.

**Why not a cap and a gasket at the hot end?**

A gasket in the flame is the first thing to fail on a pressurised engine; closing the tube in one piece puts the only joint at the cold end.

## Fits with

- [Tri-clamp spool bored and honed: 2 in × 6 in, bore Ø48.00, a power-piston cylinder](https://xemstudio.com/objects/tri-clamp-bored-spool/)
- [Clamp-on hot-end fin sleeve for a 2 in tri-clamp tube (optional)](https://xemstudio.com/objects/tri-clamp-hot-end-fin-sleeve/)
- [Split burner shroud for a vertical 2 in tri-clamp hot end](https://xemstudio.com/objects/tri-clamp-split-burner-shroud/)
- [Free-piston displacer liner: Ø40 bore, regenerator inner wall, rim clamped in the tri-clamp joint](https://xemstudio.com/objects/fpse-displacer-cylinder/)
- [Build list: Free-piston Stirling generator, 2 in tri-clamp (pressurised, linear alternator)](https://xemstudio.com/objects/list-fpse-generator-2in/)