HTD hot cup: 10 in tri-clamp closed-end cup (welded floor) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/htd-hot-cup-10in/  (CC BY 4.0)
Basis: Fabrication spec: an L14AM7-type 10 in ferrule end on Ø254 × 3.40 tube, closed by a 12.7 plate welded flush with the tube OD; exact geometry
Catalog version: 2026-10-20

Sizes: see table below
- The hot face is one piece: the floor is welded to the tube, so the only joint is the clamp at the top, 48 mm of tube wall above the flame (main HTD). That wall is also the engine's biggest heat leak: about 335 W conducted from a 450 °C floor to a 77 °C cap at 16 W/m·K (a lower-conductivity wall leaks proportionally less).
- Floor: 12.7 thick. At the 6 bar gauge relief setting, treated as simply supported at the bore (conservative for a welded edge), it sees 70 MPa at the centre and bows 0.25 mm (Roark Table 11.2). The floor must be rated for that at its working temperature; I hold the hot face at or below 450 °C.
- The cup's own ferrule face takes the standard 10 in gasket and clamp.

part  length_mm  floor_mm  chamber_face_to_floor_mm
hot-cup-10in-60.4  60.4  12.7  47.7

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Steel & O'Brien: Sanitary products catalog 2024: 16AMP end caps 10 / 12 in (A 0.480, B 10.570 / 12.570 in); L14AM7 ferrules 1.500 in; clamp ratings 13MHHM, 13MHP, 13ASME — PDF — publisher's catalogue; dimensions cited, nothing copied — https://www.steelobrien.com/wp-content/uploads/2024/03/Sanitary-2024-FINAL.pdf
- Holland Applied Technologies: Sanitary tri-clamp fittings: EG14AM7 ferrules 8 / 10 / 12 in (1.500, bore 9.732 / 11.732 in, tube 10.000 / 12.000 in); EG16A caps (10.570 / 12.570 in) — PDF — publisher's catalogue; dimensions cited, nothing copied — https://hollandapt.com/wp-content/uploads/2022/12/Sanitary-Tri-Clamp-Fittings.pdf
- McGraw-Hill: Young & Budynas, Roark's Formulas for Stress and Strain, 7th ed.: Table 8.1 (fixed–guided beam), Table 11.2 (circular plates under uniform pressure) — book — formulas are facts [verify license at link] — https://www.accessengineeringlibrary.com/content/book/9780071742474
- 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/htd-hot-cup-10in/index.json
API: https://xemstudio.com/api/geometry?object=htd-hot-cup-10in