ASME B16.11 / BS 3799 Forged Screwed Pipe Fittings
Rajtilak Metal is an ISO 9001 certified, EIL and IBR approved manufacturer and global supplier of ASME B16.11 forged threaded fittings. Designed for high-integrity, high-pressure, and severe thermal-cycle piping networks, our screwed fittings offer robust mechanical performance without the necessity of welding, facilitating rapid installation and field maintenance.
Each fitting is forged from certified raw material blooms, precision-machined on CNC turning centers, and rigorously gauged to national and international thread standards including ASME B1.20.1 NPT, BSPT (ISO 7-1), and BSPP (ISO 228-1). We export directly to offshore platforms, LNG cryogenic complexes, downstream refineries, and high-pressure steam distribution systems worldwide.
Engineers India Limited (EIL) and Indian Boiler Regulations (IBR) certified. Supplied strictly with EN 10204 3.1 Mill Test Certificates. Individual heat-number stamping ensures unbroken melt-to-spool pedigree across all critical process lines.
Manufacturing Scope & Technical Specifications
All threaded fittings are manufactured strictly adhering to the dimensional, rating, tolerance, and metallurgy matrices dictated by ASME B16.11 and BS 3799.
| Parameter | Manufacturing Standard / Scope |
|---|---|
| Design Standards | ASME B16.11, BS 3799, MSS SP-79, MSS SP-83 (Unions), MSS SP-97 (Threadolets), JIS B2302 |
| Pressure Ratings | Class 2000 (standard), Class 3000 (heavy), Class 6000 (extra heavy) |
| Nominal Size Range | 1/8″ NB to 4″ NB (DN 6 to DN 100) |
| Thread Configurations | NPT (National Pipe Taper - ASME B1.20.1), BSPT (ISO 7-1 / BS 21), BSPP (ISO 228-1) |
| Stainless Steel Grades | ASTM / ASME A182 F304, F304L, F304H, F316, F316L, F316Ti, F317L, F321, F347, F904L |
| Carbon & Low Temp Steel | ASTM A105 / A105N (Normalized), ASTM A350 LF2 Class 1/2 (Cryogenic Impact Tested) |
| Alloy & Duplex Steel | ASTM A182 F11, F22, F91; Duplex UNS S31803 / S32205; Super Duplex UNS S32750 / S32760 |
| High Nickel Alloys | Inconel 625 / 825, Hastelloy C276, Monel 400, Nickel 200/201, Titanium Grades 2 & 5 |
| Testing & Inspection | Hydrostatic test, PMI spectrometry, Liquid Penetrant Testing (LPT), Hardness (NACE MR0175/ISO 15156) |
Comprehensive ASME B16.11 Threaded Fittings Product Range
We manufacture a complete selection of high-pressure threaded pipe fittings forged from solid billet stock, ensuring dense grain flow, zero internal porosity, and exceptional resistance to mechanical vibration.
Engineering Dimensions: ASME B16.11 Threaded Elbows, Tees & Crosses
Dimensions for 90-degree elbows, 45-degree elbows, equal tees, reducing tees, and crosses across Class 2000, 3000, and 6000 pressure ratings (All linear dimensions expressed in millimeters).
| DN | NPS | Center-to-End (A) - 90° Elbow, Tee, Cross | Center-to-End (C) - 45° Elbow | Outside Dia. Band (H) | Min. Wall Thickness (G) | Min. Thread Length | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| CL 2000 | CL 3000 | CL 6000 | CL 2000 | CL 3000 | CL 6000 | CL 2000 | CL 3000 | CL 6000 | CL 2000 | CL 3000 | CL 6000 | B (Min) | L2 (Nom) | ||
| 6 | 1/8″ | 21 | 21 | 25 | 17 | 17 | 19 | 22 | 22 | 25 | 3.18 | 3.18 | 6.35 | 6.4 | 6.7 |
| 8 | 1/4″ | 21 | 25 | 28 | 17 | 19 | 22 | 22 | 25 | 33 | 3.18 | 3.30 | 6.60 | 8.1 | 10.2 |
| 10 | 3/8″ | 25 | 28 | 33 | 19 | 22 | 25 | 25 | 33 | 38 | 3.18 | 3.51 | 6.98 | 9.1 | 10.4 |
| 15 | 1/2″ | 28 | 33 | 38 | 22 | 25 | 28 | 33 | 38 | 46 | 3.18 | 4.09 | 8.15 | 10.9 | 13.6 |
| 20 | 3/4″ | 33 | 38 | 44 | 25 | 28 | 33 | 38 | 46 | 56 | 3.18 | 4.32 | 8.53 | 12.7 | 13.9 |
| 25 | 1″ | 38 | 44 | 51 | 28 | 33 | 35 | 46 | 56 | 62 | 3.68 | 4.98 | 9.93 | 14.7 | 17.3 |
| 32 | 1-1/4″ | 44 | 51 | 60 | 33 | 35 | 43 | 56 | 62 | 75 | 3.89 | 5.28 | 10.59 | 17.0 | 18.0 |
| 40 | 1-1/2″ | 51 | 60 | 64 | 35 | 43 | 44 | 62 | 75 | 84 | 4.01 | 5.56 | 11.07 | 17.8 | 18.4 |
| 50 | 2″ | 60 | 64 | 83 | 43 | 44 | 52 | 75 | 86 | 102 | 4.27 | 7.14 | 12.09 | 19.0 | 19.2 |
| 65 | 2-1/2″ | 76 | 83 | 95 | 52 | 52 | 64 | 92 | 102 | 121 | 5.61 | 7.65 | 15.29 | 23.6 | 28.9 |
| 80 | 3″ | 86 | 95 | 106 | 64 | 64 | 79 | 109 | 121 | 146 | 5.99 | 8.84 | 16.64 | 25.9 | 30.5 |
| 100 | 4″ | 106 | 114 | 114 | 79 | 79 | 79 | 146 | 152 | 152 | 6.55 | 11.18 | 18.67 | 27.7 | 33.0 |
Engineering Dimensions: Couplings and End Pipe Caps
Dimension data for ASME B16.11 full couplings, half couplings, and end caps (All values in millimeters).
| DN | NPS | End-to-End Couplings (W) | End-to-End Caps (P) | Outside Dia. (D) | Min. End Wall Thick. (G) | Min. Thread Length | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| CL 3000 & CL 6000 | CL 3000 | CL 6000 | CL 3000 | CL 6000 | CL 3000 | CL 6000 | B (Min) | L2 (Nom) | ||
| 6 | 1/8″ | 32 | 19 | — | 16 | 22 | 4.8 | — | 6.4 | 6.7 |
| 8 | 1/4″ | 35 | 25 | 27 | 19 | 25 | 4.8 | 6.4 | 8.1 | 10.2 |
| 10 | 3/8″ | 38 | 25 | 27 | 22 | 32 | 4.8 | 6.4 | 9.1 | 10.4 |
| 15 | 1/2″ | 48 | 32 | 33 | 28 | 38 | 6.4 | 7.9 | 10.9 | 13.6 |
| 20 | 3/4″ | 51 | 37 | 38 | 35 | 44 | 6.4 | 7.9 | 12.7 | 13.9 |
| 25 | 1″ | 60 | 41 | 43 | 44 | 57 | 9.7 | 11.2 | 14.7 | 17.3 |
| 32 | 1-1/4″ | 67 | 44 | 46 | 57 | 64 | 9.7 | 11.2 | 17.0 | 18.0 |
| 40 | 1-1/2″ | 79 | 44 | 48 | 64 | 76 | 11.2 | 12.7 | 17.8 | 18.4 |
| 50 | 2″ | 86 | 48 | 51 | 76 | 92 | 12.7 | 15.7 | 19.0 | 19.2 |
| 65 | 2-1/2″ | 92 | 60 | 64 | 92 | 108 | 15.7 | 19.0 | 23.6 | 28.9 |
| 80 | 3″ | 108 | 65 | 68 | 108 | 127 | 19.0 | 22.4 | 25.9 | 30.5 |
| 100 | 4″ | 121 | 68 | 75 | 140 | 159 | 22.4 | 28.4 | 27.7 | 33.0 |
Pressure-Temperature Working Ratings (ASME B16.11)
The pressure capability of threaded pipe fittings corresponds to nominal pipe wall schedules according to ASME B16.11 design principles. Working pressure limits decrease as service operating temperatures rise.
| Design Temperature | Class 2000 Rating (psig) | Class 3000 Rating (psig) by Size Scope | |||
|---|---|---|---|---|---|
| (°F) | (°C) | 1/4″ to 4″ | 1/4″ – 1″ | 1-1/4″ – 2″ | 2-1/2″ – 3″ |
| -20 to 150 | -29 to 66 | 2000 | 3000 | 2500 | 2000 |
| 200 | 93 | 1785 | 2650 | 2200 | 1780 |
| 250 | 121 | 1575 | 2250 | 1950 | 1570 |
| 300 | 149 | 1360 | 1850 | 1700 | 1360 |
| 350 | 177 | 1150 | 1500 | 1450 | 1150 |
| 400 | 204 | 935 | 1200 | 1150 | 935 |
| 450 | 232 | 725 | 950 | 900 | 725 |
| 500 | 260 | 510 | 700 | 650 | 510 |
| 550 | 288 | 300 | 450 | 400 | 300 |
NPT Thread Geometry as per ANSI/ASME B1.20.1
Taper pipe thread specifications guaranteeing leak-free metal-to-metal sealing with appropriate thread sealant or PTFE compound.
| Nominal Size (NPS) | Major Diameter (mm) | Tap Drill Size (mm) | Threads Per Inch (TPI) | Pitch (mm) |
|---|---|---|---|---|
| 1/8″ | 10.242 | 8.25 | 27 | 0.941 |
| 1/4″ | 13.616 | 10.70 | 18 | 1.411 |
| 3/8″ | 17.055 | 14.10 | 18 | 1.411 |
| 1/2″ | 21.223 | 17.40 | 14 | 1.814 |
| 3/4″ | 26.568 | 22.60 | 14 | 1.814 |
| 1″ | 33.228 | 28.50 | 11.5 | 2.209 |
| 1-1/4″ | 41.985 | 37.00 | 11.5 | 2.209 |
| 1-1/2″ | 48.054 | 43.50 | 11.5 | 2.209 |
| 2″ | 60.092 | 55.00 | 11.5 | 2.209 |
| 2-1/2″ | 72.699 | 65.50 | 8 | 3.175 |
| 3″ | 88.608 | 81.50 | 8 | 3.175 |
| 4″ | 113.973 | 107.00 | 8 | 3.175 |
BSPT & BSPP Pipe Thread Dimensions (ISO 7-1 / ISO 228-1)
Dimensional data for international procurement requiring British Standard Pipe Tapered and Parallel configurations.
| Thread Size (in – TPI) | Dash Size | BSPT Male OD (mm) | BSPP Male OD (mm) | BSPT Female ID (mm) | BSPP Female ID (mm) |
|---|---|---|---|---|---|
| 1/8″ – 28 | -02 | 9.5 | 9.6 | 8.4 | 8.6 |
| 1/4″ – 19 | -04 | 12.8 | 13.0 | 11.2 | 11.9 |
| 3/8″ – 19 | -06 | 16.3 | 16.5 | 14.7 | 15.2 |
| 1/2″ – 14 | -08 | 20.4 | 20.8 | 18.3 | 19.1 |
| 3/4″ – 14 | -12 | 25.9 | 26.3 | 23.9 | 24.6 |
| 1″ – 11 | -16 | 32.6 | 33.1 | 29.7 | 30.7 |
| 1-1/4″ – 11 | -20 | 41.1 | 41.8 | 38.6 | 39.4 |
| 1-1/2″ – 11 | -24 | 47.0 | 47.7 | 44.5 | 45.5 |
| 2″ – 11 | -32 | 58.6 | 59.5 | 56.4 | 57.4 |
| 2-1/2″ – 11 | -40 | 74.1 | 75.1 | 71.9 | 72.6 |
| 3″ – 11 | -48 | 86.6 | 87.9 | 84.6 | 85.4 |
Manufacturing Tolerances (ASME B16.11)
| Fitting Feature | Permissible Dimensional Tolerance | |
|---|---|---|
| Center-to-End Dimension (A) | 1/8″ and 1/4″ | ± 0.8 mm (± 0.03″) |
| 3/8″ to 3/4″ | ± 1.5 mm (± 0.06″) | |
| 1″ to 2″ | ± 2.0 mm (± 0.08″) | |
| 2-1/2″ to 4″ | ± 2.5 mm (± 0.10″) | |
| Threaded Bore Diameter (B) | 1-1/2″ and Smaller | + 0.5 mm / - 0.0 mm (+ 0.020″ / - 0.000″) |
| 2″ to 4″ | + 0.6 mm / - 0.0 mm (+ 0.025″ / - 0.000″) | |
| Wall Thickness (G) | All Diameters | Minimum wall shall not be less than 87.5% of nominal nominal design |
Technical Comparison: Socket Weld vs. Threaded Fittings
When configuring small-bore piping networks (under 2 inches), piping engineers generally evaluate between Threaded (Screwed) Fittings and Socket Weld Fittings:
- Installation Simplicity: Threaded fittings eliminate on-site welding equipment, purge gas, and pre/post-weld heat treatment, dramatically lowering erection costs in hazardous areas where hot work permits are restricted.
- Thermal & Fatigue Resistance: Socket weld fittings offer superior mechanical integrity against fatigue in cyclic vibration or severe thermal shocking, as threaded joints can introduce localized stress concentrations at root threads.
- Corrosion Hazards: For toxic, crevice-corrosion prone, or explosive media, socket weld or buttweld designs prevent fluid accumulation. Threaded systems are ideal for high-pressure utilities, hydraulics, gas manifolds, and non-crevice chemical duties.