Tri-clamp thermal-break spacer, 2 in × 25.4 mm: an insulating section with its own two clamp faces — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-thermal-break-spacer/  (CC BY 4.0)
Basis: Design values; faces from the shared ISO 2852 ferrule profile (gen_hardware.tc_spool); conduction estimates are mine (assumptions stated)
Catalog version: 2026-10-20

Sizes: see table below
- Two clamp faces on one short insulating body: clamp it between a warm section and a part that must stay cool (an alternator, a seal, magnets). Each face has its own gasket and clamp, so the heat path through it is only its own wall.
- Why not a ring in one joint: every tri-clamp joint already has a gasket between the faces, and the metal path across a joint is the clamp itself, which grips both rims on their 20° cones. A thin insulating ring in a joint adds little; the clamp still bridges it. With the spacer, the two clamps never touch each other.
- Where it goes: only where the temperature suits what it is made of. On my modular thermoacoustic engine it can only sit at the cold joint (above the ambient exchanger, at the cooling water's temperature); the hot joint runs at about 550 °C, which an insulating ring rated to about 260 °C cannot take.
- What it costs there: its bore adds 27.1 mm of cold gas between the stack and the piston, which lowers the pressure swing per stroke: 4.3 W against 10.2 W at the design point (model). So it is optional on that engine.
- Pressure: at a 15 bar gauge relief the hoop stress in a 1.65 wall would be 23 MPa; the builder checks that against what it is made of, at its temperature, and may leave it at 1 bar.

part  face_to_face_mm  bore_mm  outside between faces_mm  joints  clamps
break-spacer-2in-25.4  25.4  47.5  50.8  2  2

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- ISO (via iTeh sample): ISO 2852 clamp liners: face profile and flange / groove diameters — PDF — standard excerpt; dimensions are facts — https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf
- ASME: BPE Bioprocessing Equipment (tube OD and wall, clamp fittings) — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment
- Xem Studio: tools/gen_ta_modular.py: the section geometry, the network model and every number on these pages — code — CC BY 4.0 — https://xemstudio.com/
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tri-clamp-thermal-break-spacer/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-thermal-break-spacer