{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "tri-clamp-caps-with-welded-boss",
 "name": "Tri-clamp end caps with a welded boss (fabrication spec): 2 in cap with a ¾ in ferrule, ¾ in cap with a 1/4 NPT boss",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Sanitary clamp fittings",
 "year": null,
 "question": "How do I join a small line or an instrument to a 2 inch tri-clamp engine?",
 "tags": [
  "cap",
  "end cap",
  "boss",
  "npt",
  "adapter",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "tri clamp cap with npt",
  "tri clamp reducing cap",
  "2 inch cap 3/4 ferrule",
  "tri clamp gauge port cap"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 2,
 "url": "https://xemstudio.com/objects/tri-clamp-caps-with-welded-boss/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-caps-with-welded-boss/sheet.txt",
 "sheet": {
  "basis": "16AMP end-cap profile and ISO 2852 faces as gen_sanitary.cap; ¾ in tube Ø19.05 × 1.65 and ferrule; 1/4 NPT tap drill 7/16 in (ASME B1.20.1) with the thread drawn as its drill, the convention of this site's thread envelopes",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "2 in cap with a ¾ in ferrule: a standard 2 in cap with a ¾ in tube welded on its axis, ending 25.4 mm out in a full ¾ in ferrule, bored Ø15.75 through. It turns a 2 in end into a ¾ in clamp end without a reducer, clear of the 2 in clamp.",
   "¾ in cap with a 1/4 NPT boss: a standard ¾ in cap with a Ø19 boss welded on, tapped 1/4 NPT; a gauge, a fill valve or a relief valve screws in.",
   "Both are things a sanitary fabricator makes from a drawing: a cap, a short tube or a boss, one weld.",
   "Fits: faces are clamp faces; the NPT hole is a taper thread (drawn at its tap drill)."
  ],
  "table": {
   "columns": [
    "file",
    "base",
    "added",
    "bore"
   ],
   "rows": [
    [
     "cap-2in-x-0.75in-ferrule",
     "2 in cap",
     "¾ in ferrule on a 25.4 stub",
     "Ø15.75"
    ],
    [
     "cap-0.75in-x-1-4npt",
     "¾ in cap",
     "Ø19 × 12 boss",
     "1/4 NPT, Ø4 through"
    ]
   ]
  }
 },
 "sheet_text": "Tri-clamp end caps with a welded boss (fabrication spec): 2 in cap with a ¾ in ferrule, ¾ in cap with a 1/4 NPT boss — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-caps-with-welded-boss/  (CC BY 4.0)\nBasis: 16AMP end-cap profile and ISO 2852 faces as gen_sanitary.cap; ¾ in tube Ø19.05 × 1.65 and ferrule; 1/4 NPT tap drill 7/16 in (ASME B1.20.1) with the thread drawn as its drill, the convention of this site's thread envelopes\nCatalog version: 2026-10-20\n\nSizes: see table below\n- 2 in cap with a ¾ in ferrule: a standard 2 in cap with a ¾ in tube welded on its axis, ending 25.4 mm out in a full ¾ in ferrule, bored Ø15.75 through. It turns a 2 in end into a ¾ in clamp end without a reducer, clear of the 2 in clamp.\n- ¾ in cap with a 1/4 NPT boss: a standard ¾ in cap with a Ø19 boss welded on, tapped 1/4 NPT; a gauge, a fill valve or a relief valve screws in.\n- Both are things a sanitary fabricator makes from a drawing: a cap, a short tube or a boss, one weld.\n- Fits: faces are clamp faces; the NPT hole is a taper thread (drawn at its tap drill).\n\nfile  base  added  bore\ncap-2in-x-0.75in-ferrule  2 in cap  ¾ in ferrule on a 25.4 stub  Ø15.75\ncap-0.75in-x-1-4npt  ¾ in cap  Ø19 × 12 boss  1/4 NPT, Ø4 through\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- ASME: BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall) — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment\n- 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\n- ASME: ASME B1.20.1 pipe threads (NPT): 1/4 NPT tap drill 7/16 in (11.1 mm) as on this site's thread envelopes — standard — dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/tri-clamp-caps-with-welded-boss/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-caps-with-welded-boss\n",
 "sources": [
  {
   "publisher": "ASME",
   "title": "BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall)",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment",
   "formats": [
    "standard"
   ],
   "license": "ASME; dimensions are facts",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "ISO (via iTeh sample)",
   "title": "ISO 2852 clamp liners: face profile and flange / groove diameters",
   "url": "https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf",
   "formats": [
    "PDF"
   ],
   "license": "standard excerpt; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "ASME B1.20.1 pipe threads (NPT): 1/4 NPT tap drill 7/16 in (11.1 mm) as on this site's thread envelopes",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch",
   "formats": [
    "standard"
   ],
   "license": "dimensions are facts",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "sanitary-clamp-end-caps",
  "tri-clamp-port-cap",
  "npt-thread-envelopes",
  "list-ta-ring-3x2in"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [
  {
   "feature": "2 in cap face",
   "exact": "ISO 2852 (16AMP profile)",
   "mates": "standard clamp + Type B gasket",
   "fit": "clamp",
   "files": "cap-2in-x-"
  },
  {
   "feature": "¾ in ferrule face",
   "exact": "ISO 2852, 25.0 flange, 25.4 + 6.35 from the 2 in face",
   "mates": "standard ¾ in clamp + Type B gasket",
   "fit": "clamp",
   "files": "cap-2in-x-"
  },
  {
   "feature": "bore",
   "exact": "Ø15.75 through cap and stub",
   "mates": "gas passage (no contact)",
   "fit": "designed",
   "files": "cap-2in-x-"
  },
  {
   "feature": "¾ in cap face",
   "exact": "ISO 2852, 25.0 flange",
   "mates": "standard ¾ in clamp + Type B gasket",
   "fit": "clamp",
   "files": "cap-0.75in-x-"
  },
  {
   "feature": "port",
   "exact": "1/4-18 NPT, tap drill Ø11.1 × 12 (ASME B1.20.1), Ø4 on through",
   "mates": "fill valve, pressure gauge or relief valve, 1/4 NPT male",
   "fit": "designed",
   "files": "cap-0.75in-x-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "Why not a reducer?",
   "a": "A 2 × ¾ in reducer is long and holds gas; at the core's ambient end every cm³ of dead volume costs power, so the cap with a short stub keeps it small."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "cap-2in-x-0.75in-ferrule",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-caps-with-welded-boss/cap-2in-x-0.75in-ferrule.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-caps-with-welded-boss/cap-2in-x-0.75in-ferrule.stl",
   "note": "2 in end cap (16AMP profile, Ø64 × 6.35) with a ¾ in tube on its axis ending 25.4 mm behind the cap in a full ¾ in ferrule face (Ø25.0); Ø15.75 bore through"
  },
  {
   "file": "cap-0.75in-x-1-4npt",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-caps-with-welded-boss/cap-0.75in-x-1-4npt.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-caps-with-welded-boss/cap-0.75in-x-1-4npt.stl",
   "note": "¾ in end cap (25.0 flange, 4.775 thick) with a Ø19 × 12 boss, 1/4 NPT (tap drill Ø11.1) 12 deep, Ø4 on through"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-caps-with-welded-boss/index.md"
}