{ "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": "npt-thread-dimensions-asme-b1-20-1", "name": "NPT pipe thread dimensions (ASME B1.20.1): TPI, E0, E1, L1, L2 and tap drill, NPS 1/8 to 6 + male NPT end STEP/STL", "kind": "standard", "category": "Tri-clamp & pipe", "group": "Pipe, tube & threads", "year": null, "question": "What are the NPT thread dimensions (threads per inch, pitch diameter E0 and E1, hand-tight engagement L1, effective length L2) and the tap drill for each pipe size from 1/8 to 6 inch?", "tags": [ "npt", "pipe thread", "tapered", "b1.20.1", "tap drill", "female thread", "male thread", "standard", "taper 1:16" ], "aliases": [ "npt thread chart", "npt thread dimensions", "npt pipe thread size chart", "1 1/2 npt thread od", "2 inch npt tpi", "1 1/4 npt tap drill", "3/4 npt tap drill size", "1/2 npt tap drill", "npt tap drill chart", "asme b1.20.1", "npt e0 e1 l1 l2", "npt thread engagement length", "npt pitch diameter", "npt hand tight engagement", "npt 11.5 tpi", "3 inch npt threads per inch", "npt thread stl", "npt male step file", "2 1/2 npt thread", "4 inch npt thread length" ], "overall_mm": { "length": null, "width": null, "height": null }, "official_cad": false, "xem_status": "free-files", "les": false, "free_files": 9, "url": "https://xemstudio.com/objects/npt-thread-dimensions-asme-b1-20-1/", "sheet_txt": "https://xemstudio.com/objects/npt-thread-dimensions-asme-b1-20-1/sheet.txt", "sheet": { "basis": "Chicago Tube's ASME B1.20.1 table, matched with Torqbolt, Engineers Edge and Zoro and checked against the standard's own relations; tap drills from LBL, Allied Machine and Torqbolt (they disagree and each is shown); ASME B1.20.1 itself is paywalled", "overall_mm": { "length": null, "width": null, "height": null }, "notes": [ "NPT (ASME B1.20.1, 'American National Standard taper pipe thread'): 60 degree thread on a 1:16 taper on diameter (3/4 in per foot, a half-angle of 1 deg 47 min). The sizes are names (NPS), not thread diameters: the thread is cut on pipe of the OD in column 4. TPI is 27 / 18 / 14 / 11.5 / 8 depending on size. E0 is the pitch diameter at the small end of the external thread (the pipe end), L1 the hand-tight engagement length, E1 the pitch diameter at that plane (E1 = E0 + L1 / 16), L2 the effective external thread length (full threads), h the basic thread height 0.8 p.", "Where the numbers come from: the table is Chicago Tube and Iron's reprint of B1.20.1 (NPS 1/8 to 8). Every E0, L1 and L2 was matched with a second and third reading: Torqbolt's table (E0, L2 for every size), Engineers Edge (E0 and L2 for 1/16 to 4; L1 as 'hand-tight engaged') and Zoro's chart (OD, TPI and L1 for 1/16 to 4; its 'tap drill' column is actually E0). In every row E1 = E0 + L1 / 16, L2 = (0.8 D + 6.8) / n and E0 = D - (0.05 D + 1.1) / n to the printed digits (checked when this page was built), so the five-decimal values are consistent with each other. ASME's own page for the standard was reached but only its front matter is public.", "Disagreements: NPS 3 E0 is 3.34062 in (Torqbolt, Engineers Edge 3.3406, and the relation above); Chicago Tube prints 3.34052 and Zoro prints 3.34139; NPS 4 Zoro prints 4.33441 against 4.33438 (Chicago Tube, Torqbolt, Engineers Edge). The values here are the 3.34062 / 4.33438 that three sources and the relation agree on. Zoro and Engineers Edge also print 0.180 / 0.200 for 1/8 and 1/4 where Chicago Tube prints 0.1615 / 0.2278; the Chicago Tube value is used because it is consistent with E1 = E0 + L1 / 16 and with its own E1 column.", "Female tap drills are shop practice, not a thread dimension of the standard (Appendix B of B1.20.1 lists them; that appendix was not readable). Three sources were read: LBL (with and without taper reamer, 1/16 to 2), Allied Machine (no reamer, 1/8 to 4) and Torqbolt (both columns, 1/16 to 6; several fractions garbled in extraction, those were read from its decimal column). They disagree on the no-reamer drill for most sizes, so each source's value is shown. NPS 5 and 6 appear only in Torqbolt. The cut drill is not the final bore: a taper reamer or the tap itself finishes the taper. Always check against the tap maker's chart.", "Files: 9 male NPT ends, NPS 1-1/4 to 6, as single revolved solids on a Sch 40 stub (Sch 40 wall from the steel-pipe page, bore = OD minus two walls). The threaded length L2 is drawn as a plain cone at the pitch diameter, E0 at the pipe end growing at 1:16 to E0 + L2 / 16, followed by the pipe OD; the real thread (crests at E + h, roots at E - h) and the vanish threads (L4) are not drawn. The 20 mm stub behind the thread is an example length. NPS 1/8 to 1 male envelopes are on npt-bsp-thread-envelopes. No female thread is drawn: the female side is a tapered tapped hole, whose drilled bore is given in the last two columns.", "Left out: NPS 1/16 and 8 and up, thread tolerances (+/- one turn on the gauge), NPTF dry-seal, NPSC, NPSM and NPSL straight pipe threads (different pages), wrench make-up length and E3 (Engineers Edge prints them)." ], "table": { "columns": [ "NPS", "TPI", "pitch, mm", "pipe OD D, in (mm)", "E0 pitch dia at pipe end, in (mm)", "L1 hand-tight engagement, in (mm)", "E1 pitch dia at L1, in (mm)", "L2 effective thread, in (mm)", "thread height h, in (mm)", "female tap drill, with taper reamer", "female tap drill, no reamer (sources differ)" ], "rows": [ [ "1/8", "27", "0.941", "0.405 (10.29)", "0.36351 (9.233)", "0.1615 (4.10)", "0.37360 (9.489)", "0.2639 (6.70)", "0.0296 (0.75)", "21/64 (LBL, Torqbolt)", "Q = 0.332 (LBL, Allied, Torqbolt)" ], [ "1/4", "18", "1.411", "0.540 (13.72)", "0.47739 (12.126)", "0.2278 (5.79)", "0.49163 (12.487)", "0.4018 (10.21)", "0.0444 (1.13)", "27/64 (LBL, Torqbolt)", "7/16 (LBL, Allied, Torqbolt)" ], [ "3/8", "18", "1.411", "0.675 (17.14)", "0.61201 (15.545)", "0.2400 (6.10)", "0.62701 (15.926)", "0.4078 (10.36)", "0.0444 (1.13)", "9/16 (LBL, Torqbolt)", "37/64 (LBL, Torqbolt) / 9/16 (Allied)" ], [ "1/2", "14", "1.814", "0.840 (21.34)", "0.75843 (19.264)", "0.3200 (8.13)", "0.77843 (19.772)", "0.5337 (13.56)", "0.0571 (1.45)", "11/16 (LBL, Torqbolt)", "45/64 (Allied, Torqbolt) / 23/32 (LBL)" ], [ "3/4", "14", "1.814", "1.050 (26.67)", "0.96768 (24.579)", "0.3390 (8.61)", "0.98887 (25.117)", "0.5457 (13.86)", "0.0571 (1.45)", "57/64 (LBL, Torqbolt)", "29/32 (Allied, Torqbolt) / 59/64 (LBL)" ], [ "1", "11.5", "2.209", "1.315 (33.40)", "1.21363 (30.826)", "0.400 (10.16)", "1.23863 (31.461)", "0.6828 (17.34)", "0.0696 (1.77)", "1-1/8 (LBL, Torqbolt)", "1-9/64 (Allied) / 1-5/32 (LBL) / 1-9/32 (Torqbolt)" ], [ "1-1/4", "11.5", "2.209", "1.660 (42.16)", "1.55713 (39.551)", "0.4200 (10.67)", "1.58338 (40.218)", "0.7068 (17.95)", "0.0696 (1.77)", "1-15/32 (LBL, Torqbolt)", "1-31/64 (Allied, Torqbolt) / 1-1/2 (LBL)" ], [ "1-1/2", "11.5", "2.209", "1.900 (48.26)", "1.79609 (45.621)", "0.4200 (10.67)", "1.82234 (46.287)", "0.7235 (18.38)", "0.0696 (1.77)", "1-23/32 (LBL, Torqbolt)", "1-23/32 (Allied, Torqbolt) / 1-47/64 (LBL)" ], [ "2", "11.5", "2.209", "2.375 (60.32)", "2.26902 (57.633)", "0.4360 (11.07)", "2.29627 (58.325)", "0.7565 (19.22)", "0.0696 (1.77)", "2-3/16 (LBL) / 2-5/32 (Torqbolt)", "2-7/32 (Allied, LBL) / 2-3/16 (Torqbolt)" ], [ "2-1/2", "8", "3.175", "2.875 (73.02)", "2.71953 (69.076)", "0.6820 (17.32)", "2.76216 (70.159)", "1.1375 (28.89)", "0.1000 (2.54)", "—", "2-5/8 (Allied, Torqbolt)" ], [ "3", "8", "3.175", "3.500 (88.90)", "3.34062 (84.852)", "0.7660 (19.46)", "3.38850 (86.068)", "1.2000 (30.48)", "0.1000 (2.54)", "—", "3-1/4 (Allied, Torqbolt)" ], [ "3-1/2", "8", "3.175", "4.000 (101.60)", "3.83750 (97.472)", "0.8210 (20.85)", "3.88881 (98.776)", "1.2500 (31.75)", "0.1000 (2.54)", "—", "3-3/4 (Allied, Torqbolt)" ], [ "4", "8", "3.175", "4.500 (114.30)", "4.33438 (110.093)", "0.8440 (21.44)", "4.38712 (111.433)", "1.3000 (33.02)", "0.1000 (2.54)", "—", "4-1/4 (Allied, Torqbolt)" ], [ "5", "8", "3.175", "5.563 (141.30)", "5.39073 (136.925)", "0.9370 (23.80)", "5.44929 (138.412)", "1.4063 (35.72)", "0.1000 (2.54)", "—", "5-9/32 (Torqbolt only)" ], [ "6", "8", "3.175", "6.625 (168.27)", "6.44609 (163.731)", "0.9580 (24.33)", "6.50597 (165.252)", "1.5125 (38.42)", "0.1000 (2.54)", "—", "6-11/32 (Torqbolt only)" ] ] } }, "sheet_text": "NPT pipe thread dimensions (ASME B1.20.1): TPI, E0, E1, L1, L2 and tap drill, NPS 1/8 to 6 + male NPT end STEP/STL — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/npt-thread-dimensions-asme-b1-20-1/ (sheet CC BY 4.0)\nBasis: Chicago Tube's ASME B1.20.1 table, matched with Torqbolt, Engineers Edge and Zoro and checked against the standard's own relations; tap drills from LBL, Allied Machine and Torqbolt (they disagree and each is shown); ASME B1.20.1 itself is paywalled\nCatalog version: 2026-10-20\n\nSizes: see table below\n- NPT (ASME B1.20.1, 'American National Standard taper pipe thread'): 60 degree thread on a 1:16 taper on diameter (3/4 in per foot, a half-angle of 1 deg 47 min). The sizes are names (NPS), not thread diameters: the thread is cut on pipe of the OD in column 4. TPI is 27 / 18 / 14 / 11.5 / 8 depending on size. E0 is the pitch diameter at the small end of the external thread (the pipe end), L1 the hand-tight engagement length, E1 the pitch diameter at that plane (E1 = E0 + L1 / 16), L2 the effective external thread length (full threads), h the basic thread height 0.8 p.\n- Where the numbers come from: the table is Chicago Tube and Iron's reprint of B1.20.1 (NPS 1/8 to 8). Every E0, L1 and L2 was matched with a second and third reading: Torqbolt's table (E0, L2 for every size), Engineers Edge (E0 and L2 for 1/16 to 4; L1 as 'hand-tight engaged') and Zoro's chart (OD, TPI and L1 for 1/16 to 4; its 'tap drill' column is actually E0). In every row E1 = E0 + L1 / 16, L2 = (0.8 D + 6.8) / n and E0 = D - (0.05 D + 1.1) / n to the printed digits (checked when this page was built), so the five-decimal values are consistent with each other. ASME's own page for the standard was reached but only its front matter is public.\n- Disagreements: NPS 3 E0 is 3.34062 in (Torqbolt, Engineers Edge 3.3406, and the relation above); Chicago Tube prints 3.34052 and Zoro prints 3.34139; NPS 4 Zoro prints 4.33441 against 4.33438 (Chicago Tube, Torqbolt, Engineers Edge). The values here are the 3.34062 / 4.33438 that three sources and the relation agree on. Zoro and Engineers Edge also print 0.180 / 0.200 for 1/8 and 1/4 where Chicago Tube prints 0.1615 / 0.2278; the Chicago Tube value is used because it is consistent with E1 = E0 + L1 / 16 and with its own E1 column.\n- Female tap drills are shop practice, not a thread dimension of the standard (Appendix B of B1.20.1 lists them; that appendix was not readable). Three sources were read: LBL (with and without taper reamer, 1/16 to 2), Allied Machine (no reamer, 1/8 to 4) and Torqbolt (both columns, 1/16 to 6; several fractions garbled in extraction, those were read from its decimal column). They disagree on the no-reamer drill for most sizes, so each source's value is shown. NPS 5 and 6 appear only in Torqbolt. The cut drill is not the final bore: a taper reamer or the tap itself finishes the taper. Always check against the tap maker's chart.\n- Files: 9 male NPT ends, NPS 1-1/4 to 6, as single revolved solids on a Sch 40 stub (Sch 40 wall from the steel-pipe page, bore = OD minus two walls). The threaded length L2 is drawn as a plain cone at the pitch diameter, E0 at the pipe end growing at 1:16 to E0 + L2 / 16, followed by the pipe OD; the real thread (crests at E + h, roots at E - h) and the vanish threads (L4) are not drawn. The 20 mm stub behind the thread is an example length. NPS 1/8 to 1 male envelopes are on npt-bsp-thread-envelopes. No female thread is drawn: the female side is a tapered tapped hole, whose drilled bore is given in the last two columns.\n- Left out: NPS 1/16 and 8 and up, thread tolerances (+/- one turn on the gauge), NPTF dry-seal, NPSC, NPSM and NPSL straight pipe threads (different pages), wrench make-up length and E3 (Engineers Edge prints them).\n\nNPS TPI pitch, mm pipe OD D, in (mm) E0 pitch dia at pipe end, in (mm) L1 hand-tight engagement, in (mm) E1 pitch dia at L1, in (mm) L2 effective thread, in (mm) thread height h, in (mm) female tap drill, with taper reamer female tap drill, no reamer (sources differ)\n1/8 27 0.941 0.405 (10.29) 0.36351 (9.233) 0.1615 (4.10) 0.37360 (9.489) 0.2639 (6.70) 0.0296 (0.75) 21/64 (LBL, Torqbolt) Q = 0.332 (LBL, Allied, Torqbolt)\n1/4 18 1.411 0.540 (13.72) 0.47739 (12.126) 0.2278 (5.79) 0.49163 (12.487) 0.4018 (10.21) 0.0444 (1.13) 27/64 (LBL, Torqbolt) 7/16 (LBL, Allied, Torqbolt)\n3/8 18 1.411 0.675 (17.14) 0.61201 (15.545) 0.2400 (6.10) 0.62701 (15.926) 0.4078 (10.36) 0.0444 (1.13) 9/16 (LBL, Torqbolt) 37/64 (LBL, Torqbolt) / 9/16 (Allied)\n1/2 14 1.814 0.840 (21.34) 0.75843 (19.264) 0.3200 (8.13) 0.77843 (19.772) 0.5337 (13.56) 0.0571 (1.45) 11/16 (LBL, Torqbolt) 45/64 (Allied, Torqbolt) / 23/32 (LBL)\n3/4 14 1.814 1.050 (26.67) 0.96768 (24.579) 0.3390 (8.61) 0.98887 (25.117) 0.5457 (13.86) 0.0571 (1.45) 57/64 (LBL, Torqbolt) 29/32 (Allied, Torqbolt) / 59/64 (LBL)\n1 11.5 2.209 1.315 (33.40) 1.21363 (30.826) 0.400 (10.16) 1.23863 (31.461) 0.6828 (17.34) 0.0696 (1.77) 1-1/8 (LBL, Torqbolt) 1-9/64 (Allied) / 1-5/32 (LBL) / 1-9/32 (Torqbolt)\n1-1/4 11.5 2.209 1.660 (42.16) 1.55713 (39.551) 0.4200 (10.67) 1.58338 (40.218) 0.7068 (17.95) 0.0696 (1.77) 1-15/32 (LBL, Torqbolt) 1-31/64 (Allied, Torqbolt) / 1-1/2 (LBL)\n1-1/2 11.5 2.209 1.900 (48.26) 1.79609 (45.621) 0.4200 (10.67) 1.82234 (46.287) 0.7235 (18.38) 0.0696 (1.77) 1-23/32 (LBL, Torqbolt) 1-23/32 (Allied, Torqbolt) / 1-47/64 (LBL)\n2 11.5 2.209 2.375 (60.32) 2.26902 (57.633) 0.4360 (11.07) 2.29627 (58.325) 0.7565 (19.22) 0.0696 (1.77) 2-3/16 (LBL) / 2-5/32 (Torqbolt) 2-7/32 (Allied, LBL) / 2-3/16 (Torqbolt)\n2-1/2 8 3.175 2.875 (73.02) 2.71953 (69.076) 0.6820 (17.32) 2.76216 (70.159) 1.1375 (28.89) 0.1000 (2.54) — 2-5/8 (Allied, Torqbolt)\n3 8 3.175 3.500 (88.90) 3.34062 (84.852) 0.7660 (19.46) 3.38850 (86.068) 1.2000 (30.48) 0.1000 (2.54) — 3-1/4 (Allied, Torqbolt)\n3-1/2 8 3.175 4.000 (101.60) 3.83750 (97.472) 0.8210 (20.85) 3.88881 (98.776) 1.2500 (31.75) 0.1000 (2.54) — 3-3/4 (Allied, Torqbolt)\n4 8 3.175 4.500 (114.30) 4.33438 (110.093) 0.8440 (21.44) 4.38712 (111.433) 1.3000 (33.02) 0.1000 (2.54) — 4-1/4 (Allied, Torqbolt)\n5 8 3.175 5.563 (141.30) 5.39073 (136.925) 0.9370 (23.80) 5.44929 (138.412) 1.4063 (35.72) 0.1000 (2.54) — 5-9/32 (Torqbolt only)\n6 8 3.175 6.625 (168.27) 6.44609 (163.731) 0.9580 (24.33) 6.50597 (165.252) 1.5125 (38.42) 0.1000 (2.54) — 6-11/32 (Torqbolt only)\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Chicago Tube and Iron: ASME standard taper pipe thread dimensions (NPT): D, TPI, E0, L2, V, E1, L1, E3, L3, NPS 1/8 to 8 — web — Publisher's page; dimensions are facts — https://www.chicagotube.com/products-2/valves-fittings/asme-standard-taper-pipe-thread-dimensions/\n- Torqbolt: NPT threads: dimensions and specifications, tap drill sizes (NPS 1/16 to 24; some fractions garbled in extraction) — web — Publisher's page; dimensions are facts — https://torqbolt.com/npt-threads-national-tapered-pipe-threads-dimensions-specifications\n- Engineers Edge: Standard taper pipe threads NPT: L3, E3, V, L4, L5, E5, thread height h, K0 — web — Publisher's page; dimensions are facts — https://www.engineersedge.com/hardware/standard_taper_pipe_threads_npt_15544.htm\n- Engineers Edge: External (pipe) thread design: NPT pitch diameters E0, E-tolerances, hand-tight engagement and effective thread length, NPS 1/16 to 4 — web — Publisher's page; dimensions are facts — https://ns1.engineersedge.com/pipe_external_thrd.htm\n- Zoro: NPT size chart: OD, TPI, E0 (printed there as 'tap drill') and L1, NPS 1/16 to 4 — web — Publisher's page; dimensions are facts — https://www.zoro.com/resourcehub/npt-size-chart/\n- Lawrence Berkeley National Laboratory (G. Meigs): Tap chart, pipe threads: drill size with and without taper reamer, NPT and straight pipe thread, 1/16 to 2 — web — Publisher's page; dimensions are facts — https://bl831.als.lbl.gov/~gmeigs/scripting_help/NPT_tap_size.htm\n- Allied Machine: Tap drill charts: NPT / NPTF drill size without taper reamer, 1/8 to 4 — web — Publisher's page; dimensions are facts — https://alliedmachine.com/Online-Tools/Tap-Drill-Charts/Unified-National.aspx\n- ASME: B1.20.1-2013 Pipe Threads, General Purpose (Inch): front matter only (Table 2 basic dimensions, Appendix B tap drills are in the paywalled body) — web — Publisher's page; dimensions are facts — https://www.asme.org/getmedia/1a201f23-e83c-42f6-bb4f-90b94e25960c/35257.pdf\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 9 parts): https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/index.json\nAPI: https://xemstudio.com/api/geometry?object=npt-thread-dimensions-asme-b1-20-1\n", "sources": [ { "publisher": "Chicago Tube and Iron", "title": "ASME standard taper pipe thread dimensions (NPT): D, TPI, E0, L2, V, E1, L1, E3, L3, NPS 1/8 to 8", "url": "https://www.chicagotube.com/products-2/valves-fittings/asme-standard-taper-pipe-thread-dimensions/", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "Torqbolt", "title": "NPT threads: dimensions and specifications, tap drill sizes (NPS 1/16 to 24; some fractions garbled in extraction)", "url": "https://torqbolt.com/npt-threads-national-tapered-pipe-threads-dimensions-specifications", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "Engineers Edge", "title": "Standard taper pipe threads NPT: L3, E3, V, L4, L5, E5, thread height h, K0", "url": "https://www.engineersedge.com/hardware/standard_taper_pipe_threads_npt_15544.htm", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "Engineers Edge", "title": "External (pipe) thread design: NPT pitch diameters E0, E-tolerances, hand-tight engagement and effective thread length, NPS 1/16 to 4", "url": "https://ns1.engineersedge.com/pipe_external_thrd.htm", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "Zoro", "title": "NPT size chart: OD, TPI, E0 (printed there as 'tap drill') and L1, NPS 1/16 to 4", "url": "https://www.zoro.com/resourcehub/npt-size-chart/", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "Lawrence Berkeley National Laboratory (G. Meigs)", "title": "Tap chart, pipe threads: drill size with and without taper reamer, NPT and straight pipe thread, 1/16 to 2", "url": "https://bl831.als.lbl.gov/~gmeigs/scripting_help/NPT_tap_size.htm", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "Allied Machine", "title": "Tap drill charts: NPT / NPTF drill size without taper reamer, 1/8 to 4", "url": "https://alliedmachine.com/Online-Tools/Tap-Drill-Charts/Unified-National.aspx", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "ASME", "title": "B1.20.1-2013 Pipe Threads, General Purpose (Inch): front matter only (Table 2 basic dimensions, Appendix B tap drills are in the paywalled body)", "url": "https://www.asme.org/getmedia/1a201f23-e83c-42f6-bb4f-90b94e25960c/35257.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": [ "npt-thread-envelopes", "steel-pipe-asme-b36-10m-nps-1-8-to-24", "stainless-steel-pipe-asme-b36-19m-sch-5s-10s-40s-80s", "schedule-40-pipe", "forged-threaded-fittings-b16-11", "malleable-iron-fittings-class-150", "tri-clamp-male-npt-adapters", "tri-clamp-female-npt-adapters", "thread-reference-tap-drills-clearance", "garden-hose-thread", "copper-pipe-type-l-m" ], "fits": [], "dimensions": "exact (nominal, no tolerance added)", "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no tolerance added. 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. Typical accuracy by process and ISO 286 fits: https://xemstudio.com/tolerances/", "mating": [ { "feature": "male taper thread, pitch diameter at the pipe end E0", "exact": "E0 1-1/4 / 1-1/2 / 2 / 2-1/2 / 3 / 4 / 6 NPT = Ø39.55 / 45.62 / 57.63 / 69.08 / 84.85 / 110.09 / 163.73 mm (1:16 taper, thread not drawn)", "mates": "internal NPT thread of the same size, hand-tight at L1 where the pitch diameters are equal (E1 = E0 + L1 / 16); fittings on forged-threaded-fittings-b16-11 and malleable-iron-fittings-class-150", "fit": "designed", "files": "npt-male-nipple-" }, { "feature": "pipe OD behind the thread", "exact": "Ø42.16 / 48.26 / 60.33 / 73.03 / 88.90 / 114.30 / 168.28 mm for 1-1/4 / 1-1/2 / 2 / 2-1/2 / 3 / 4 / 6", "mates": "butt-weld and threaded fittings of the same NPS (steel-pipe-asme-b36-10m-nps-1-8-to-24)", "fit": "designed", "files": "npt-male-nipple-" }, { "feature": "bore (Sch 40 stub)", "exact": "Ø35.05 / 40.89 / 52.50 / 62.71 / 77.93 / 102.26 / 154.05 mm", "mates": "flow passage; the wall at the thread tip is the pitch diameter minus the bore, so a thin tip is not drawn away", "fit": "designed", "files": "npt-male-nipple-" } ], "fit_classes": { "press": "stays put: pin, tube, bearing or magnet held by interference. ISO 286 equivalent: H7/p6 (locational interference) or tighter.", "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. ISO 286 equivalent: H7/g6 or H7/h6.", "run": "turns or slides in use: pin in a link, rod through a guide. ISO 286 equivalent: H8/f7 (close running).", "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. ISO 286 equivalent: H9/d9 (free running) or looser.", "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": "How many threads per inch is a 1-1/2 NPT?", "a": "11.5. NPS 1, 1-1/4, 1-1/2 and 2 are 11.5 TPI; 1/2 and 3/4 are 14; 1/4 and 3/8 are 18; 1/8 is 27; 2-1/2 and up are 8." }, { "q": "What is the outside diameter of 2 inch NPT?", "a": "2.375 in (60.33 mm): the thread is cut on 2 inch pipe, so the thread's largest size is just under the pipe OD." }, { "q": "What is the pitch diameter of a 3/4 NPT?", "a": "E0 = 0.96768 in (24.58 mm) at the pipe end, 0.98887 in (25.12 mm) at the hand-tight plane (L1 = 0.339 in)." }, { "q": "What drill size for 1/2 NPT?", "a": "Shop charts give 11/16 in with a taper reamer and 45/64 in or 23/32 in without; the sources read disagree, see the table and check your tap maker's chart." }, { "q": "How long is the NPT thread on a 1 inch pipe?", "a": "L2 = 0.6828 in (17.34 mm) of full thread, hand-tight engagement L1 = 0.400 in (10.16 mm)." }, { "q": "Is the CAD an exact thread?", "a": "No: the files are the pitch-diameter cone of the male end on a Sch 40 stub; the thread form is not drawn." } ], "files_license": null, "offers": [ { "file": "npt-male-nipple-1-1-4-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-1-1-4-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-1-1-4-sch40.stl", "note": "1-1/4 NPT male end on a Sch 40 pipe stub: OD 42.16 mm, bore 35.05 mm (Sch 40 wall); the threaded length L2 = 17.95 mm is a plain pitch-diameter cone, 39.55 mm at the pipe end (E0) growing to 40.67 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 37.95 mm are examples" }, { "file": "npt-male-nipple-1-1-2-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-1-1-2-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-1-1-2-sch40.stl", "note": "1-1/2 NPT male end on a Sch 40 pipe stub: OD 48.26 mm, bore 40.89 mm (Sch 40 wall); the threaded length L2 = 18.38 mm is a plain pitch-diameter cone, 45.62 mm at the pipe end (E0) growing to 46.77 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 38.38 mm are examples" }, { "file": "npt-male-nipple-2-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-2-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-2-sch40.stl", "note": "2 NPT male end on a Sch 40 pipe stub: OD 60.32 mm, bore 52.50 mm (Sch 40 wall); the threaded length L2 = 19.22 mm is a plain pitch-diameter cone, 57.63 mm at the pipe end (E0) growing to 58.83 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 39.22 mm are examples" }, { "file": "npt-male-nipple-2-1-2-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-2-1-2-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-2-1-2-sch40.stl", "note": "2-1/2 NPT male end on a Sch 40 pipe stub: OD 73.02 mm, bore 62.71 mm (Sch 40 wall); the threaded length L2 = 28.89 mm is a plain pitch-diameter cone, 69.08 mm at the pipe end (E0) growing to 70.88 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 48.89 mm are examples" }, { "file": "npt-male-nipple-3-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-3-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-3-sch40.stl", "note": "3 NPT male end on a Sch 40 pipe stub: OD 88.90 mm, bore 77.93 mm (Sch 40 wall); the threaded length L2 = 30.48 mm is a plain pitch-diameter cone, 84.85 mm at the pipe end (E0) growing to 86.76 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 50.48 mm are examples" }, { "file": "npt-male-nipple-3-1-2-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-3-1-2-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-3-1-2-sch40.stl", "note": "3-1/2 NPT male end on a Sch 40 pipe stub: OD 101.60 mm, bore 90.12 mm (Sch 40 wall); the threaded length L2 = 31.75 mm is a plain pitch-diameter cone, 97.47 mm at the pipe end (E0) growing to 99.46 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 51.75 mm are examples" }, { "file": "npt-male-nipple-4-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-4-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-4-sch40.stl", "note": "4 NPT male end on a Sch 40 pipe stub: OD 114.30 mm, bore 102.26 mm (Sch 40 wall); the threaded length L2 = 33.02 mm is a plain pitch-diameter cone, 110.09 mm at the pipe end (E0) growing to 112.16 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 53.02 mm are examples" }, { "file": "npt-male-nipple-5-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-5-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-5-sch40.stl", "note": "5 NPT male end on a Sch 40 pipe stub: OD 141.30 mm, bore 128.19 mm (Sch 40 wall); the threaded length L2 = 35.72 mm is a plain pitch-diameter cone, 136.92 mm at the pipe end (E0) growing to 139.16 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 55.72 mm are examples" }, { "file": "npt-male-nipple-6-sch40", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-6-sch40.step", "stl": "https://xemstudio.com/files/hardware/npt-thread-dimensions-asme-b1-20-1/npt-male-nipple-6-sch40.stl", "note": "6 NPT male end on a Sch 40 pipe stub: OD 168.27 mm, bore 154.05 mm (Sch 40 wall); the threaded length L2 = 38.42 mm is a plain pitch-diameter cone, 163.73 mm at the pipe end (E0) growing to 166.13 mm (taper 1:16 on diameter), thread form not drawn; 20 mm stub behind it and the overall length 58.42 mm are examples" } ], "markdown": "https://xemstudio.com/objects/npt-thread-dimensions-asme-b1-20-1/index.md" }