MSS-SP-97 is a standard developed by the Manufacturers Standardization Society (MSS) for integrally reinforced forged branch outlet fittings. This standard includes essential dimensions, finishes, tolerances, testing, marking, material, and minimum strength requirements. It covers fittings for buttwelding, socket welding, and threaded types, ensuring reliable performance and quality. The fittings are designed for 90° and 45° branch connections and are used widely in piping systems for various industrial applications
MSS SP-97-2019 Integrally Reinforced Forged Branch Outlet Fittings Size – Socket Welding, Threaded and Buttwelding Ends
MSS SP-97-2019 includes essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90° and 45° integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types.
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Unless specified otherwise by the manufacturer, conventional integrally reinforced forged branch outlet fittings are intended for the following header by branch combinations: STD × STD, XS × XS, SCH. 160 × SCH 160, XXS × XXS, XS × 3000, SCH 160 × 6000, and XXS × 9000. When the run and branch pipes are of differing or mixed schedules, then the selection of the branch connection shall be determined by contacting the manufacturer. Such selections shall be agreed upon by purchaser and manufacturer at time of order and may involve supplemental marking requirements determined by other standards (e.g., material grade determination, other factors). See Section 1.3. Mixed schedule branch outlet fittings are unique to the design of each system, and thus outside the scope of this Standard Practice. The adequacy of the design for light, intermediate, and heavy wall branch outlet fittings may be established by mathematical analysis as contained in the applicable pressure vessel or piping codes, or by finite element analysis.
MSS SP-97-2019 Integrally Reinforced Forged Branch Outlet Fittings Size
Dimensions Size on Size Weldolet STD – MSS SP97
| NPS | . | A | B | C | D | L |
| 1/2 | INCH | 3/4 | 1-3/8 | 15/16 | 5/8 | 1-3/16 |
| . | MM | 19.05 | 34.93 | 23.81 | 15.88 | 30.16 |
| 3/4 | INCH | 7/8 | 1-5/8 | 1-3/16 | 13/16 | 1-7/16 |
| . | MM | 22.23 | 41.28 | 30.16 | 20.64 | 36.51 |
| 1 | INCH | 1-1/16 | 2 | 1-7/16 | 1-1/32 | 1-1/16 |
| . | MM | 26.99 | 50.80 | 36.51 | 26.19 | 26.99 |
| 1¼ | INCH | 1-1/4 | 2-3/8 | 1-3/4 | 1-3/8 | 2-1/16 |
| . | MM | 31.75 | 60.3 | 44.45 | 34.93 | 52.39 |
| 1½ | INCH | 1-5/16 | 2-7/8 | 2 | 1-5/8 | 2-1/4 |
| . | MM | 33.34 | 73 | 50.80 | 41.28 | 57.15 |
| 2 | INCH | 1-1/2 | 3-1/2 | 2-9/16 | 2-1/16 | 2-11/16 |
| . | MM | 38.10 | 88.90 | 65.09 | 52.39 | 68.26 |
| 2½ | INCH | 1-5/8 | 4-1/16 | 3 | 2-7/16 | 3-1/16 |
| . | MM | 41.28 | 103.19 | 76.20 | 61.91 | 77.79 |
| 3 | INCH | 1-3/4 | 4-13/16 | 3-11/16 | 3-1/16 | 3-1/2 |
| . | MM | 44.45 | 122.24 | 93.66 | 77.79 | 88.90 |
| 3½ | INCH | 2 | 5-3/8 | 3-7/8 | 3-9/16 | 3-7/8 |
| . | MM | 50.80 | 136.53 | 98.43 | 90.49 | 98.43 |
| 4 | INCH | 2 | 6 | 4-3/4 | 4 | 4-1/4 |
| . | MM | 50.80 | 152.40 | 120.65 | 101.60 | 107.95 |
| 5 | INCH | 2-1/4 | 7-1/8 | 5-9/16 | 5-1/16 | 5-1/16 |
| . | MM | 57.15 | 180.98 | 141.29 | 128.59 | 128.59 |
| 6 | INCH | 2-3/8 | 8-1/2 | 6-11/16 | 6-1/16 | 5-11/16 |
| . | MM | 60.3 | 215.90 | 169.86 | 153.99 | 144.46 |
| 8 | INCH | 2-3/4 | 10-3/8 | 8-11/16 | 7-15/16 | 7-1/16 |
| . | MM | 69.85 | 263.53 | 220.66 | 201.61 | 179.39 |
| 10 | INCH | 3-1/16 | 12-9/16 | 10-13/16 | 10 | 8-7/16 |
| . | MM | 77.79 | 319.09 | 274.64 | 254.00 | 214.31 |
| 12 | INCH | 3-3/8 | 14-7/8 | 12-13/16 | 12 | 9-3/4 |
| . | MM | 85.73 | 377.83 | 325.44 | 304.80 | 247.65 |
| 14 | INCH | 3-1/2 | 16-1/8 | 14-1/16 | 13-1/4 | 10-1/2 |
| . | MM | 88.90 | 409.58 | 357.19 | 336.55 | 266.70 |
| 16 | INCH | 3-11/16 | 18-1/4 | 16-1/16 | 15-1/4 | 11-11/16 |
| . | MM | 93.66 | 463.55 | 407.99 | 387.35 | 296.86 |
| 18 | INCH | 4-1/16 | 20-3/4 | 18-5/8 | 17-1/4 | 13-1/16 |
| . | MM | 103.19 | 527.05 | 473.08 | 438.15 | 331.79 |
| 20 | INCH | 4-5/8 | 23-1/16 | 20-1/16 | 19-1/4 | 14-5/8 |
| . | MM | 117.48 | 585.79 | 509.59 | 488.95 | 371.48 |
| 24 | INCH | 5-3/8 | 27-7/8 | 25-1/8 | 23-1/4 | 17-3/8 |
| . | MM | 136.53 | 708.03 | 638.18 | 590.55 | 441.33 |
Dimensions Weldolet Reducing – STD – MSS SP97
| NPS | . | A | B | C |
| 1/2 | INCH | 3/4 | 1-3/8 | 15/16 |
| . | MM | 19.05 | 34.93 | 23.81 |
| 3/4 | INCH | 7/8 | 1-3/4 | 1-3/16 |
| . | MM | 22.23 | 44.45 | 30.16 |
| 1 | INCH | 1-1/16 | 2-1/8 | 1-7/16 |
| . | MM | 26.99 | 53.98 | 36.51 |
| 1¼ | INCH | 1-1/4 | 2-9/16 | 1-3/4 |
| . | MM | 31.75 | 65.09 | 44.45 |
| 1½ | INCH | 1-5/16 | 2-7/8 | 2 |
| . | MM | 33.34 | 73 | 50.80 |
| 2 | INCH | 1-1/2 | 3-1/2 | 2-9/16 |
| . | MM | 38.10 | 88.90 | 65.09 |
| 2½ | INCH | 1-5/8 | 4-1/16 | 3 |
| . | MM | 41.28 | 103.19 | 76.20 |
| 3 | INCH | 1-3/4 | 4-13/16 | 3-11/16 |
| . | MM | 44.45 | 122.24 | 93.66 |
| 3½ | INCH | 1-7/8 | 5-5/8 | 4 |
| . | MM | 47.63 | 142.88 | 101.60 |
| 4 | INCH | 2 | 6 | 4-3/4 |
| . | MM | 50.80 | 152.40 | 120.65 |
| 5 | INCH | 2-1/4 | 7-1/16 | 5-9/16 |
| . | MM | 57.15 | 179.39 | 141.29 |
| 6 | INCH | 2-3/8 | 8-1/2 | 6-11/16 |
| . | MM | 60.3 | 215.90 | 169.86 |
| 8 | INCH | 2-3/4 | 10-3/8 | 8-11/16 |
| . | MM | 69.85 | 263.53 | 220.66 |
| 10 | INCH | 3-1/16 | 12-11/16 | 10-13/16 |
| . | MM | 77.79 | 322.26 | 274.64 |
| 12 | INCH | 3-3/8 | 14-7/8 | 12-13/16 |
| . | MM | 85.73 | 377.83 | 325.44 |
| 14 | INCH | 3-1/2 | 16-1/8 | 14-1/16 |
| . | MM | 88.90 | 409.58 | 357.19 |
| 16 | INCH | 3-11/16 | 18-1/4 | 16-1/16 |
| . | MM | 93.66 | 463.55 | 407.99 |
| 18 | INCH | 3-13/16 | 20-1/2 | 18-1/16 |
| . | MM | 96.84 | 520.70 | 458.79 |
| 20 | INCH | 4 | 22-1/2 | 20 |
| . | MM | 101.60 | 571.50 | 508.00 |
| 24 | INCH | 4-9/16 | 27-1/8 | 24-3/16 |
| . | MM | 115.89 | 688.98 | 614.36 |
Dimensions (L) Center Line of Run Pipe to Face of Weldolet
| NPS | . | Outlet Sizes STD and XS NPS 1/2 – 4 | |||||||||
| . | . | 1/2 | 3/4 | 1 | 11/4 | 11/2 | 2 | 21/2 | 3 | 31/2 | 4 |
| 3/4 | INCH | 1-1/4 | |||||||||
| . | MM | 31.75 | |||||||||
| 1 | INCH | 1-3/8 | 1-1/2 | ||||||||
| . | MM | 34.92 | 38.10 | ||||||||
| 1¼ | INCH | 1-9/16 | 1-11/16 | 1-7/8 | |||||||
| . | MM | 39.68 | 42.86 | 47.62 | |||||||
| 1½ | INCH | 1-11/16 | 1-13/16 | 2 | 2-3/16 | ||||||
| . | MM | 42.86 | 46.03 | 50.80 | 55.56 | ||||||
| 2 | INCH | 1-15/16 | 2-1/16 | 2-1/4 | 2-7/16 | 2-1/2 | |||||
| . | MM | 49.21 | 52.38 | 57.15 | 61.91 | 63.50 | |||||
| 2½ | INCH | 2-3/16 | 2-5/16 | 2-1/2 | 2-11/16 | 2-3/4 | 2-15/16 | ||||
| . | MM | 55.56 | 58.73 | 63.50 | 68.26 | 69.85 | 74.61 | ||||
| 3 | INCH | 2-1/2 | 2-5/8 | 2-13/16 | 3 | 3-1/16 | 3-1/4 | 3-3/8 | |||
| . | MM | 63.5 | 66.67 | 71.43 | 76.20 | 77.78 | 82.55 | 85.72 | |||
| 3½ | INCH | 2-3/4 | 2-7/8 | 3-1/16 | 3-1/4 | 3-5/16 | 3-1/2 | 3-5/8 | 3-3/4 | ||
| . | MM | 69.85 | 73.02 | 77.78 | 82.55 | 84.13 | 88.9 | 92.07 | 95.25 | ||
| 4 | INCH | 3 | 3-1/8 | 3-5/16 | 3-1/2 | 3-9/16 | 3-3/4 | 3-7/8 | 4 | 4-1/8 | |
| . | MM | 76.2 | 79.37 | 84.13 | 88.90 | 90.48 | 95.25 | 98.42 | 101.60 | 104.77 | |
| 5 | INCH | 3-9/16 | 3-11/16 | 3-7/8 | 4-1/16 | 4-1/8 | 4-5/16 | 4-7/16 | 4-9/16 | 4-11/16 | 4-13/16 |
| . | MM | 90.48 | 93.66 | 98.42 | 103.18 | 104.77 | 109.53 | 112.71 | 115.88 | 119.06 | 122.23 |
| 6 | INCH | 4-1/16 | 4-3/16 | 4-3/8 | 4-9/16 | 4-5/8 | 4-13/16 | 4-15/16 | 5-1/16 | 5-3/16 | 5-5/16 |
| . | MM | 103.18 | 106.36 | 111.12 | 115.88 | 117.47 | 122.23 | 125.41 | 128.58 | 131.76 | 134.93 |
| 8 | INCH | 5-1/16 | 5-3/16 | 5-3/8 | 5-9/16 | 5-5/8 | 5-13/16 | 5-15/16 | 6-1/16 | 6-3/16 | 6-5/16 |
| . | MM | 128.58 | 131.76 | 136.52 | 141.28 | 142.87 | 147.63 | 150.81 | 153.98 | 157.16 | 160.3 |
| 10 | INCH | 6-1/8 | 6-1/4 | 6-7/16 | 6-5/8 | 6-11/16 | 6-7/8 | 7 | 7-1/8 | 7-1/4 | 7-3/8 |
| . | MM | 155.57 | 158.75 | 163.51 | 168.27 | 169.86 | 174.62 | 177.8 | 180.97 | 184.15 | 187.32 |
| 12 | INCH | 7-1/8 | 7-1/4 | 7-7/16 | 7-5/8 | 7-11/16 | 7-7/8 | 8 | 8-1/8 | 8-1/4 | 8-3/8 |
| . | MM | 180.97 | 184.15 | 188.91 | 193.67 | 195.26 | 200.02 | 203.20 | 206.37 | 209.55 | 212.72 |
| 14 | INCH | 7-3/4 | 7-7/8 | 8-1/16 | 8-1/4 | 8-5/16 | 8-1/2 | 8-5/8 | 8-3/4 | 8-7/8 | 9 |
| . | MM | 196.85 | 200.02 | 204.78 | 209.55 | 211.13 | 215.90 | 219.07 | 222.25 | 225.42 | 228.60 |
| 16 | INCH | 8-3/4 | 8-7/8 | 9-1/16 | 9-1/4 | 9-5/16 | 9-1/2 | 9-5/8 | 9-3/4 | 9-7/8 | 10 |
| . | MM | 222.25 | 225.42 | 230.18 | 234.95 | 236.53 | 241.30 | 244.47 | 247.65 | 250.82 | 254.00 |
| 18 | INCH | 9-3/4 | 9-7/8 | 10-1/16 | 10-1/4 | 10-5/16 | 10-1/2 | 10-5/8 | 10-3/4 | 10-7/8 | 11 |
| . | MM | 247.65 | 250.82 | 255.58 | 260.35 | 261.93 | 266.70 | 269.87 | 273 | 276.22 | 279.40 |
| 20 | INCH | 10-3/4 | 10-7/8 | 11-1/16 | 11-1/4 | 11-5/16 | 11-1/2 | 11-5/8 | 11-3/4 | 11-7/8 | 12 |
| . | MM | 273 | 276.22 | 280.98 | 285.75 | 287.33 | 292.10 | 295.27 | 298.45 | 301.62 | 304.80 |
| 24 | INCH | 12-3/4 | 12-7/8 | 13-1/16 | 13-1/4 | 13-5/16 | 13-1/2 | 13-5/8 | 13-3/4 | 13-7/8 | 14 |
| . | MM | 323.9 | 327.02 | 331.78 | 336.55 | 338.13 | 342.90 | 346.07 | 349.25 | 352.42 | 355.60 |
| NPS | ` | Outlet Size STD NPS 5 – 20 | ||||||||
| ` | ` | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 |
| 6 | INCH | 5-9/16 | ||||||||
| ` | MM | 141.28 | ||||||||
| 8 | INCH | 6-9/16 | 6-11/16 | |||||||
| ` | MM | 166.68 | 169.86 | |||||||
| 10 | INCH | 7-5/8 | 7-3/4 | 8-1/8 | ||||||
| ` | MM | 193.67 | 196.85 | 206.37 | ||||||
| 12 | INCH | 8-5/8 | 8-3/4 | 9-1/8 | 9-7/16 | |||||
| ` | MM | 219.07 | 222.25 | 231.77 | 239.71 | |||||
| 14 | INCH | 9-1/4 | 9-3/8 | 9-3/4 | 10-1/16 | 10-3/8 | ||||
| ` | MM | 234.95 | 238.12 | 247.65 | 255.58 | 263.52 | ||||
| 16 | INCH | 10-1/4 | 10-3/8 | 10-3/4 | 11-1/16 | 11-3/8 | 11-1/2 | |||
| ` | MM | 260.35 | 263.52 | 273 | 280.98 | 288.92 | 292.10 | |||
| 18 | INCH | 11-1/4 | 11-3/8 | 11-3/4 | 12-1/16 | 12-3/8 | 12-1/2 | 12-11/16 | ||
| ` | MM | 285.75 | 288.92 | 298.45 | 306.38 | 314.32 | 317.50 | 322.26 | ||
| 20 | INCH | 12-1/4 | 12-3/8 | 12-3/4 | 13-1/16 | 13-3/8 | 13-1/2 | 13-11/16 | 13-13/16 | |
| ` | MM | 311.15 | 314.32 | 323.9 | 331.78 | 339.72 | 342.90 | 347.66 | 350.83 | |
| 24 | INCH | 14-1/4 | 14-3/8 | 14-3/4 | 15-1/16 | 15-3/8 | 15-1/2 | 15-11/16 | 15-13/16 | 16 |
| ` | MM | 361.95 | 365.12 | 374.65 | 382.58 | 390.52 | 393.70 | 398.46 | 401.63 | 406.40 |
| NPS | ` | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 |
General notes:
- Root Gap – X – “Space” for welding the O’let is raised off the run pipe to establish proper weld gap by placing spacers, e.g. welding rods, under the fitting. This provides a uniform welding gap between the curvature of the run and base of fitting.
- X = Root Gap not included in L measure.
- L = Dimensions Center Line of Run Pipe to Face of Weldolet.
- Bevelled Ends ASME B16.9 and B16.25.
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