{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "butt-weld-reducers",
 "name": "Butt-weld reducers, concentric and eccentric (ASME B16.9), NPS ¾ to 12",
 "kind": "standard",
 "category": "Tri-clamp & pipe",
 "group": "Pipe, tube & threads",
 "year": null,
 "question": "What is the end-to-end length of a butt-weld concentric or eccentric reducer (ASME B16.9)?",
 "tags": [
  "pipe",
  "pipe fitting",
  "butt weld",
  "reducer",
  "b16.9",
  "standard"
 ],
 "aliases": [
  "butt weld reducer dimensions",
  "concentric reducer length",
  "eccentric reducer dimensions",
  "b16.9 reducer",
  "weld reducer step",
  "pipe reducer stl"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 4,
 "url": "https://xemstudio.com/objects/butt-weld-reducers/",
 "sheet_txt": "https://xemstudio.com/objects/butt-weld-reducers/sheet.txt",
 "sheet": {
  "basis": "ASME B16.9 dimensions as published in SHIELD's manufacturer table (mm); OD and Sch 40 wall per ASME B36.10 (Weldbend)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Concentric and eccentric reducers share the same end-to-end length H for each size pair. An eccentric reducer keeps one side straight (flat side down in a pump suction, up for drainage).",
   "Files: 2 × 1 and 4 × 2, concentric and eccentric, Schedule 40 at each end. The shape of the transition is the manufacturer's: the files run a straight cone over the full length between the two ends.",
   "OD and Schedule 40 wall: Weldbend prints OD rounded (1.32, 2.38 in); the files use the exact ASME B36.10 OD (1.315, 2.375, 4.500 in) with the Weldbend Sch 40 wall (.133, .154, .237 in). Fittings are made to match the pipe's OD and wall.",
   "Ends are drawn square. Real fittings are bevelled for welding to ASME B16.25; no public, citable statement of the bevel was found, so it is not drawn."
  ],
  "table": {
   "columns": [
    "size, NPS",
    "large-end OD, mm",
    "small-end OD, mm",
    "end-to-end H, mm"
   ],
   "rows": [
    [
     "3/4 × 3/8",
     "26.7",
     "17.3",
     "38"
    ],
    [
     "3/4 × 1/2",
     "26.7",
     "21.3",
     "38"
    ],
    [
     "1 × 1/2",
     "33.4",
     "21.3",
     "51"
    ],
    [
     "1 × 3/4",
     "33.4",
     "26.7",
     "51"
    ],
    [
     "1-1/4 × 1/2",
     "42.2",
     "21.3",
     "51"
    ],
    [
     "1-1/4 × 3/4",
     "42.2",
     "26.7",
     "51"
    ],
    [
     "1-1/4 × 1",
     "42.2",
     "33.4",
     "51"
    ],
    [
     "1-1/2 × 1/2",
     "48.3",
     "21.3",
     "64"
    ],
    [
     "1-1/2 × 3/4",
     "48.3",
     "26.7",
     "64"
    ],
    [
     "1-1/2 × 1",
     "48.3",
     "33.4",
     "64"
    ],
    [
     "1-1/2 × 1-1/4",
     "48.3",
     "42.2",
     "64"
    ],
    [
     "2 × 3/4",
     "60.3",
     "26.7",
     "76"
    ],
    [
     "2 × 1",
     "60.3",
     "33.4",
     "76"
    ],
    [
     "2 × 1-1/4",
     "60.3",
     "42.2",
     "76"
    ],
    [
     "2 × 1-1/2",
     "60.3",
     "48.3",
     "76"
    ],
    [
     "2-1/2 × 1",
     "73.0",
     "33.4",
     "89"
    ],
    [
     "2-1/2 × 1-1/4",
     "73.0",
     "42.2",
     "89"
    ],
    [
     "2-1/2 × 1-1/2",
     "73.0",
     "48.3",
     "89"
    ],
    [
     "2-1/2 × 2",
     "73.0",
     "60.3",
     "89"
    ],
    [
     "3 × 1-1/4",
     "88.9",
     "42.2",
     "89"
    ],
    [
     "3 × 1-1/2",
     "88.9",
     "48.3",
     "89"
    ],
    [
     "3 × 2",
     "88.9",
     "60.3",
     "89"
    ],
    [
     "3 × 2-1/2",
     "88.9",
     "73.0",
     "89"
    ],
    [
     "3-1/2 × 1-1/4",
     "101.6",
     "42.2",
     "102"
    ],
    [
     "3-1/2 × 1-1/2",
     "101.6",
     "48.3",
     "102"
    ],
    [
     "3-1/2 × 2",
     "101.6",
     "60.3",
     "102"
    ],
    [
     "3-1/2 × 2-1/2",
     "101.6",
     "73.0",
     "102"
    ],
    [
     "3-1/2 × 3",
     "101.6",
     "88.9",
     "102"
    ],
    [
     "4 × 1-1/2",
     "114.3",
     "48.3",
     "102"
    ],
    [
     "4 × 2",
     "114.3",
     "60.3",
     "102"
    ],
    [
     "4 × 2-1/2",
     "114.3",
     "73.0",
     "102"
    ],
    [
     "4 × 3",
     "114.3",
     "88.9",
     "102"
    ],
    [
     "4 × 3-1/2",
     "114.3",
     "101.6",
     "102"
    ],
    [
     "5 × 2",
     "141.3",
     "60.3",
     "127"
    ],
    [
     "5 × 2-1/2",
     "141.3",
     "73.0",
     "127"
    ],
    [
     "5 × 3",
     "141.3",
     "88.9",
     "127"
    ],
    [
     "5 × 3-1/2",
     "141.3",
     "101.6",
     "127"
    ],
    [
     "5 × 4",
     "141.3",
     "114.3",
     "127"
    ],
    [
     "6 × 2-1/2",
     "168.3",
     "73.0",
     "140"
    ],
    [
     "6 × 3",
     "168.3",
     "88.9",
     "140"
    ],
    [
     "6 × 3-1/2",
     "168.3",
     "101.6",
     "140"
    ],
    [
     "6 × 4",
     "168.3",
     "114.3",
     "140"
    ],
    [
     "6 × 5",
     "168.3",
     "141.3",
     "140"
    ],
    [
     "8 × 3-1/2",
     "219.1",
     "101.6",
     "152"
    ],
    [
     "8 × 4",
     "219.1",
     "114.3",
     "152"
    ],
    [
     "8 × 5",
     "219.1",
     "141.3",
     "152"
    ],
    [
     "8 × 6",
     "219.1",
     "168.3",
     "152"
    ],
    [
     "10 × 4",
     "273.0",
     "114.3",
     "178"
    ],
    [
     "10 × 5",
     "273.0",
     "141.3",
     "178"
    ],
    [
     "10 × 6",
     "273.0",
     "168.3",
     "178"
    ],
    [
     "10 × 8",
     "273.0",
     "219.1",
     "178"
    ],
    [
     "12 × 5",
     "323.8",
     "141.3",
     "203"
    ],
    [
     "12 × 6",
     "323.8",
     "168.3",
     "203"
    ],
    [
     "12 × 8",
     "323.8",
     "219.1",
     "203"
    ],
    [
     "12 × 10",
     "323.8",
     "273.0",
     "203"
    ]
   ]
  }
 },
 "sheet_text": "Butt-weld reducers, concentric and eccentric (ASME B16.9), NPS ¾ to 12 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/butt-weld-reducers/  (sheet CC BY 4.0)\nBasis: ASME B16.9 dimensions as published in SHIELD's manufacturer table (mm); OD and Sch 40 wall per ASME B36.10 (Weldbend)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Concentric and eccentric reducers share the same end-to-end length H for each size pair. An eccentric reducer keeps one side straight (flat side down in a pump suction, up for drainage).\n- Files: 2 × 1 and 4 × 2, concentric and eccentric, Schedule 40 at each end. The shape of the transition is the manufacturer's: the files run a straight cone over the full length between the two ends.\n- OD and Schedule 40 wall: Weldbend prints OD rounded (1.32, 2.38 in); the files use the exact ASME B36.10 OD (1.315, 2.375, 4.500 in) with the Weldbend Sch 40 wall (.133, .154, .237 in). Fittings are made to match the pipe's OD and wall.\n- Ends are drawn square. Real fittings are bevelled for welding to ASME B16.25; no public, citable statement of the bevel was found, so it is not drawn.\n\nsize, NPS  large-end OD, mm  small-end OD, mm  end-to-end H, mm\n3/4 × 3/8  26.7  17.3  38\n3/4 × 1/2  26.7  21.3  38\n1 × 1/2  33.4  21.3  51\n1 × 3/4  33.4  26.7  51\n1-1/4 × 1/2  42.2  21.3  51\n1-1/4 × 3/4  42.2  26.7  51\n1-1/4 × 1  42.2  33.4  51\n1-1/2 × 1/2  48.3  21.3  64\n1-1/2 × 3/4  48.3  26.7  64\n1-1/2 × 1  48.3  33.4  64\n1-1/2 × 1-1/4  48.3  42.2  64\n2 × 3/4  60.3  26.7  76\n2 × 1  60.3  33.4  76\n2 × 1-1/4  60.3  42.2  76\n2 × 1-1/2  60.3  48.3  76\n2-1/2 × 1  73.0  33.4  89\n2-1/2 × 1-1/4  73.0  42.2  89\n2-1/2 × 1-1/2  73.0  48.3  89\n2-1/2 × 2  73.0  60.3  89\n3 × 1-1/4  88.9  42.2  89\n3 × 1-1/2  88.9  48.3  89\n3 × 2  88.9  60.3  89\n3 × 2-1/2  88.9  73.0  89\n3-1/2 × 1-1/4  101.6  42.2  102\n3-1/2 × 1-1/2  101.6  48.3  102\n3-1/2 × 2  101.6  60.3  102\n3-1/2 × 2-1/2  101.6  73.0  102\n3-1/2 × 3  101.6  88.9  102\n4 × 1-1/2  114.3  48.3  102\n4 × 2  114.3  60.3  102\n4 × 2-1/2  114.3  73.0  102\n4 × 3  114.3  88.9  102\n4 × 3-1/2  114.3  101.6  102\n5 × 2  141.3  60.3  127\n5 × 2-1/2  141.3  73.0  127\n5 × 3  141.3  88.9  127\n5 × 3-1/2  141.3  101.6  127\n5 × 4  141.3  114.3  127\n6 × 2-1/2  168.3  73.0  140\n6 × 3  168.3  88.9  140\n6 × 3-1/2  168.3  101.6  140\n6 × 4  168.3  114.3  140\n6 × 5  168.3  141.3  140\n8 × 3-1/2  219.1  101.6  152\n8 × 4  219.1  114.3  152\n8 × 5  219.1  141.3  152\n8 × 6  219.1  168.3  152\n10 × 4  273.0  114.3  178\n10 × 5  273.0  141.3  178\n10 × 6  273.0  168.3  178\n10 × 8  273.0  219.1  178\n12 × 5  323.8  141.3  203\n12 × 6  323.8  168.3  203\n12 × 8  323.8  219.1  203\n12 × 10  323.8  273.0  203\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- SHIELD (manufacturer): Butt-welded fittings & flanges, SG-BWFF: ASME B16.9 elbows, tees, reducers (mm) — web — Publisher's page; dimensions are facts — https://www.naffco.com/media-downloads/pdf/buttwelded.pdf\n- Weldbend Corporation: Weld fitting & weld flange catalog, 63rd edition: 90° and 45° long-radius elbows, OD, STD / Sch 40 wall — web — Publisher's page; dimensions are facts — https://acceldx.roccommercecloud.com/assets/86/84/86841a47-ae63-4c4d-9881-ceba74db0969/Weldbend_131010000_Catalog.pdf\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 4 parts): https://xemstudio.com/files/hardware/butt-weld-reducers/index.json\nAPI: https://xemstudio.com/api/geometry?object=butt-weld-reducers\n",
 "sources": [
  {
   "publisher": "SHIELD (manufacturer)",
   "title": "Butt-welded fittings & flanges, SG-BWFF: ASME B16.9 elbows, tees, reducers (mm)",
   "url": "https://www.naffco.com/media-downloads/pdf/buttwelded.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Weldbend Corporation",
   "title": "Weld fitting & weld flange catalog, 63rd edition: 90° and 45° long-radius elbows, OD, STD / Sch 40 wall",
   "url": "https://acceldx.roccommercecloud.com/assets/86/84/86841a47-ae63-4c4d-9881-ceba74db0969/Weldbend_131010000_Catalog.pdf",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "butt-weld-elbows-long-radius",
  "butt-weld-equal-tees",
  "schedule-40-pipe",
  "sanitary-clamp-reducers"
 ],
 "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": [],
 "faq": [
  {
   "q": "How long is a 4 × 2 butt-weld reducer?",
   "a": "102 mm end to end, concentric or eccentric."
  },
  {
   "q": "How long is a 2 × 1 butt-weld reducer?",
   "a": "76 mm end to end."
  }
 ],
 "files_license": null,
 "offers": [
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   "file": "bw-reducer-concentric-nps2x1-sch40",
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   "license": "CC BY 4.0 (Xem Studio)",
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   "stl": "https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-concentric-nps2x1-sch40.stl",
   "note": "NPS 2 × 1 concentric reducer, Sch 40 each end, end-to-end 76 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends"
  },
  {
   "file": "bw-reducer-eccentric-nps2x1-sch40",
   "formats": [
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   "license": "CC BY 4.0 (Xem Studio)",
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   "stl": "https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps2x1-sch40.stl",
   "note": "NPS 2 × 1 eccentric reducer, Sch 40 each end, end-to-end 76 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends"
  },
  {
   "file": "bw-reducer-concentric-nps4x2-sch40",
   "formats": [
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   "license": "CC BY 4.0 (Xem Studio)",
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   "stl": "https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-concentric-nps4x2-sch40.stl",
   "note": "NPS 4 × 2 concentric reducer, Sch 40 each end, end-to-end 102 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends"
  },
  {
   "file": "bw-reducer-eccentric-nps4x2-sch40",
   "formats": [
    "step",
    "stl"
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   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps4x2-sch40.step",
   "stl": "https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps4x2-sch40.stl",
   "note": "NPS 4 × 2 eccentric reducer, Sch 40 each end, end-to-end 102 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends"
  }
 ],
 "markdown": "https://xemstudio.com/objects/butt-weld-reducers/index.md"
}