Tri-clamp × male NPT adapters (21MP style): ½ to 4 in — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-male-npt-adapters/  (CC BY 4.0)
Basis: Face-to-end A per Dixon T21MP; NPT envelope (major diameter over L2) per ASME B1.20.1; bore the smaller of the clamp bore and the Sch 40 bore
Catalog version: 2026-10-20

Sizes: see table below
- Clamp face one end, male pipe thread the other. Threads are drawn as plain cylinders at the major diameter over the effective length L2; cut or chase the thread on the part, or print the envelope as a gauge.
- Only sizes with a published A are drawn.
- Every clamp face is the ISO 2852 profile used across this site: 2.85 mm rim, flat face with the gasket groove (K 1.6 deep, R3 1.2 bottom, 23° walls, P2 0.8 edges) on C2, 20° back cone. Flange C3 / groove C2 / tube OD × wall, mm: ½–¾ in 25.0 / 20.4 (derived) / 12.7–19.05 × 1.65; 1–1½ in 50.5 / 43.5 / 25.4–38.1 × 1.65; 2 in 64.0 / 56.5 / 50.8 × 1.65; 2½ in 77.5 / 70.5 / 63.5 × 1.65; 3 in 91.0 / 83.5 / 76.2 × 1.65; 4 in 119.0 / 110.0 / 101.6 × 2.11; 6 in 166.9 (6.570 in) / 156.5 / 152.4 × 2.77; 8 in 217.7 (8.570 in) / 207.0 / 203.2 × 2.77; 10 in 268.5 / 261.0 / 254.0 × 3.40; 12 in 319.3 / 311.8 / 304.8 × 3.40.

clamp_in  npt  A_in  A_mm  thread_major_mm  L2_mm
½  ¼  2.0  50.8  13.72  10.2
½  ½  1.63  41.4  21.34  13.6
½  ¾  2.0  50.8  26.67  13.9
¾  ¾  1.79  45.5  26.67  13.9
1  ½  2.19  55.6  21.34  13.6
1  1  2.25  57.1  33.4  17.3
2  2  2.64  67.1  60.33  19.22
2½  2½  2.88  73.2  73.03  28.89
3  3  3.07  78.0  88.9  30.48
4  4  3.16  80.3  114.3  33.02

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Dixon: Clamp × male NPT (T21MP) and clamp × female NPT (T22MP) adapters: A per size — PDF — publisher's catalogue; dimensions cited — https://api.dixonvalve.com/en/media/1490003
- ASME: B1.20.1 Pipe threads, general purpose (NPT): major diameter, L2, tap drill; B16.11 forged fittings (Class 3000 couplings); B36.10 Sch 40 bore — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch
- Rubber Fab: Tri-Clamp gasket dimensional chart: gasket ID, OD and bead diameter per size (2 in bead 2.22 in / 56.50 mm, 1.5 in 1.71 / 43.50, 3 in 3.29 / 83.50) — PDF — maker chart; dimensions are facts [verify license at link] — https://shop.andersonprocess.com/media/assets/product/documents/rubber-fab-tri-clamp-dimensions.pdf

Free files (CC BY 4.0, Xem Studio; STEP + STL, 10 parts): https://xemstudio.com/files/hardware/tri-clamp-male-npt-adapters/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-male-npt-adapters