ASME B16.5 Flange
Engineering Standard Overview
Precision ASME B16.5 Pipe Flanges Manufacturer in India
Rajtilak Metal is an approved manufacturer and global exporter of ASME B16.5 / ANSI B16.5 forged pipe flanges ranging from Class 150 to Class 2500 in nominal pipe sizes from NPS 1/2" to NPS 24". Engineered to withstand high-pressure, cryogenic, and severe cyclic environments, our flanges serve global EPC contractors, refineries, and offshore platforms.
The ASME B16.5 standard establishes strict criteria for pressure-temperature ratings, material selection, mechanical tolerances, bolt hole drilling, and contact face machining. Every forged flange is certified with full traceability back to the original heat number under EN 10204 Type 3.1 inspection certification.
ISO 9001:2015 EIL & IBR Approved NACE MR0175 / ISO 15156 EN 10204 3.1 Certified
150-2500#Full Pressure Class
Table of Contents — Technical Engineering Reference
- Technical Material Specifications
- ASME B16.5 Pressure-Temperature Ratings
- ASTM Chemical Composition Limits
- Class 150 Dimensional Data
- Class 300 Dimensional Data
- Class 400 Dimensional Data
- Class 600 Dimensional Data
- Class 900 Dimensional Data
- Class 1500 Dimensional Data
- Class 2500 Dimensional Data
- Manufacturing Dimensional Tolerances
- Flange Contact Face Configurations
- Weight Chart (SORF, WNRF, BLRF)
- Stud Bolt Length & Machine Bolt Chart
- Gasket Dimensions per ASME B16.5
Technical Specification
ASME B16.5 Flange Manufacturing Specification Summary
Authoritative technical reference outlining material grades, testing compliance, facing types, and dimensional scope for procurement managers and piping design engineers.
| Parameter | ASME B16.5 Technical Standard Specification |
|---|---|
| Governing Standard | ASME B16.5 / ANSI B16.5 (Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard) |
| Nominal Size Range | NPS 1/2" to NPS 24" (DN 15 to DN 600); Sizes NPS 26" and above produced to ASME B16.47 Series A / B |
| Pressure Class Ratings | Class 150, Class 300, Class 400, Class 600, Class 900, Class 1500, Class 2500 |
| Contact Face Geometries | Raised Face (RF: 1/16" for Class 150/300; 1/4" for Class 400+), Flat Face (FF), Ring Type Joint (RTJ), Tongue & Groove (T/G), Male & Female (M/F) |
| Surface Finish Ra | Serrated Concentric or Spiral Finish (125–250 µin / 3.2–6.3 µm Ra); Smooth Finish for RTJ grooves (< 63 µin Ra) |
| Carbon Steel Grades | ASTM A105, ASTM A350 LF2 Class 1/2, ASTM A694 F42, F52, F60, F65 |
| Alloy Steel Grades | ASTM A182 F1, F5, F9, F11 Class 2, F22 Class 3, F91 (High-Temperature Steam & Refinery Service) |
| Stainless Steel Grades | ASTM A182 F304, F304L, F316, F316L, F321, F347, F310S, 904L |
| Duplex & Nickel Alloys | ASTM A182 F51 (UNS S31803), F53 (UNS S32750 2507), Inconel 625, Incoloy 825, Hastelloy C276, Monel 400 |
| Mandatory Marking | Manufacturer Logo, Material Grade, Nominal Pipe Size, Pressure Class, Flange Facing, Heat Melt Number, ASME B16.5 |
| Inspection & Certification | EN 10204 Type 3.1 MTC, PMI Spectro Analysis, Ultrasonic/Magnetic Particle Examination, Hydrostatic Proof Testing |
Product Configurations
Comprehensive ASME B16.5 Flange Portfolio
We manufacture all standardized ASME B16.5 flange types with custom bores matching Schedules 10, 20, 40, STD, 80, XS, 160, and XXS.
Weld Neck Flange (WNRF)
Slip On Flange (SORF)
Blind Flange (BLRF)
Socket Weld Flange (SWRF)
Threaded (NPT) Flange
Lap Joint Flange (LJ)
Ring Type Joint (RTJ)
Orifice Flange Assembly
Pressure Ratings
ASME B16.5 Pressure-Temperature Ratings (Material Group 1.1 - A105)
Working gauge pressures in bar (psig) for ASTM A105 forged carbon steel flanges across standard ASME pressure classes from sub-zero to elevated service temperatures.
| Service Temp (°C) | Class 150 (bar) | Class 300 (bar) | Class 400 (bar) | Class 600 (bar) | Class 900 (bar) | Class 1500 (bar) | Class 2500 (bar) |
|---|---|---|---|---|---|---|---|
| -29 to 38 | 19.6 | 51.1 | 68.1 | 102.1 | 153.2 | 255.3 | 425.5 |
| 100 | 17.7 | 46.6 | 62.1 | 93.2 | 139.8 | 233.0 | 388.3 |
| 150 | 15.8 | 45.1 | 60.1 | 90.2 | 135.2 | 225.4 | 375.6 |
| 200 | 13.8 | 43.8 | 58.4 | 87.6 | 131.4 | 219.0 | 365.0 |
| 250 | 12.1 | 41.9 | 55.9 | 83.9 | 125.8 | 209.7 | 349.5 |
| 300 | 10.2 | 39.8 | 53.1 | 79.6 | 119.5 | 199.1 | 331.8 |
| 350 | 8.4 | 37.6 | 50.1 | 75.1 | 112.7 | 187.8 | 313.0 |
| 400 | 6.5 | 34.7 | 46.3 | 69.4 | 104.2 | 173.6 | 289.3 |
| 450 | 4.6 | 23.0 | 30.7 | 46.0 | 69.0 | 115.0 | 191.7 |
| 500 | 2.8 | 11.6 | 15.4 | 23.2 | 34.7 | 57.9 | 96.5 |
Dimensional Engineering Data
ASME B16.5 Class 150 Flange Dimensions (Inches & mm)
Nominal dimensions for ASME B16.5 Class 150 Raised Face (RF) flanges, detailing outside diameter, thickness, bolt circle, and hub lengths.
| NPS (Inches) | OD (Inches) | Thickness T (Inches) | RF Dia R (Inches) | Bolt Holes No. | Hole Dia (Inches) | Bolt Circle BC (Inches) | Hub Base HB (Inches) | SO LTH SL (Inches) | WN LTH WL (Inches) |
|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 3.50 | 0.44 | 1.38 | 4 | 0.62 | 2.38 | 1.19 | 0.62 | 1.88 |
| 3/4" | 3.88 | 0.50 | 1.69 | 4 | 0.62 | 2.75 | 1.50 | 0.62 | 2.06 |
| 1" | 4.25 | 0.56 | 2.00 | 4 | 0.62 | 3.12 | 1.94 | 0.69 | 2.19 |
| 1-1/2" | 5.00 | 0.69 | 2.88 | 4 | 0.62 | 3.88 | 2.56 | 0.88 | 2.44 |
| 2" | 6.00 | 0.75 | 3.62 | 4 | 0.75 | 4.75 | 3.06 | 1.00 | 2.50 |
| 3" | 7.50 | 0.94 | 5.00 | 4 | 0.75 | 6.00 | 4.25 | 1.19 | 2.75 |
| 4" | 9.00 | 0.94 | 6.19 | 8 | 0.75 | 7.50 | 5.31 | 1.31 | 3.00 |
| 6" | 11.00 | 1.00 | 8.50 | 8 | 0.88 | 9.50 | 7.56 | 1.56 | 3.50 |
| 8" | 13.50 | 1.12 | 10.62 | 8 | 0.88 | 11.75 | 9.69 | 1.75 | 4.00 |
| 10" | 16.00 | 1.19 | 12.75 | 12 | 1.00 | 14.25 | 12.00 | 1.94 | 4.00 |
| 12" | 19.00 | 1.25 | 15.00 | 12 | 1.00 | 17.00 | 14.38 | 2.19 | 4.50 |
| 16" | 23.50 | 1.44 | 18.50 | 16 | 1.12 | 21.25 | 19.00 | 2.50 | 5.00 |
| 20" | 27.50 | 1.69 | 23.00 | 20 | 1.25 | 25.00 | 23.50 | 2.88 | 5.69 |
| 24" | 32.00 | 1.88 | 27.25 | 20 | 1.38 | 29.50 | 28.12 | 3.25 | 6.00 |
Dimensional Engineering Data
ASME B16.5 Class 300 Flange Dimensions
Nominal dimensions for ASME B16.5 Class 300 medium-pressure forged pipe flanges, detailing bolt hole circle, raised face diameter, and length through hub.
| NPS (Inches) | OD (Inches) | Thickness T (Inches) | RF Dia R (Inches) | Bolt Holes No. | Hole Dia (Inches) | Bolt Circle BC (Inches) | SO Bore SB (Inches) | SO LTH SL (Inches) | WN LTH WL (Inches) |
|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 3.75 | 0.56 | 1.38 | 4 | 0.62 | 2.62 | 0.88 | 0.88 | 2.06 |
| 3/4" | 4.62 | 0.62 | 1.69 | 4 | 0.75 | 3.25 | 1.09 | 1.00 | 2.25 |
| 1" | 4.88 | 0.69 | 2.00 | 4 | 0.75 | 3.50 | 1.36 | 1.06 | 2.44 |
| 1-1/2" | 6.12 | 0.81 | 2.88 | 4 | 0.88 | 4.50 | 1.95 | 1.19 | 2.69 |
| 2" | 6.50 | 0.88 | 3.62 | 8 | 0.75 | 5.00 | 2.44 | 1.31 | 2.75 |
| 3" | 8.25 | 1.12 | 5.00 | 8 | 0.88 | 6.62 | 3.57 | 1.69 | 3.12 |
| 4" | 10.00 | 1.25 | 6.19 | 8 | 0.88 | 7.88 | 4.57 | 1.88 | 3.38 |
| 6" | 12.50 | 1.44 | 8.50 | 12 | 0.88 | 10.62 | 6.72 | 2.06 | 3.88 |
| 8" | 15.00 | 1.62 | 10.62 | 12 | 1.00 | 13.00 | 8.72 | 2.44 | 4.38 |
| 10" | 17.50 | 1.88 | 12.75 | 16 | 1.12 | 15.25 | 10.88 | 2.62 | 4.62 |
| 12" | 20.50 | 2.00 | 15.00 | 16 | 1.25 | 17.75 | 12.88 | 2.88 | 5.12 |
| 16" | 25.50 | 2.25 | 18.50 | 20 | 1.38 | 22.50 | 16.16 | 3.25 | 5.75 |
| 20" | 30.50 | 2.50 | 23.00 | 24 | 1.38 | 27.00 | 20.20 | 3.75 | 6.38 |
| 24" | 36.00 | 2.75 | 27.25 | 24 | 1.62 | 32.00 | 24.25 | 4.19 | 6.62 |
Dimensional Engineering Data
ASME B16.5 Class 600 Flange Dimensions
Engineering dimensions for Class 600 high-pressure piping flanges, suitable for high-yield oil and gas pipeline tie-ins.
| NPS (Inches) | OD (Inches) | Thickness T (Inches) | RF Dia R (Inches) | Bolt Holes No. | Hole Dia (Inches) | Bolt Circle BC (Inches) | Hub Base HB (Inches) | SO LTH SL (Inches) | WN LTH WL (Inches) |
|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 3.75 | 0.56 | 1.38 | 4 | 0.62 | 2.62 | 1.50 | 0.88 | 2.06 |
| 3/4" | 4.62 | 0.62 | 1.69 | 4 | 0.75 | 3.25 | 1.88 | 1.00 | 2.25 |
| 1" | 4.88 | 0.69 | 2.00 | 4 | 0.75 | 3.50 | 2.12 | 1.06 | 2.44 |
| 1-1/2" | 6.12 | 0.88 | 2.88 | 4 | 0.88 | 4.50 | 2.75 | 1.25 | 2.75 |
| 2" | 6.50 | 1.00 | 3.62 | 8 | 0.75 | 5.00 | 3.31 | 1.44 | 2.88 |
| 3" | 8.25 | 1.25 | 5.00 | 8 | 0.88 | 6.62 | 4.62 | 1.81 | 3.25 |
| 4" | 10.75 | 1.50 | 6.19 | 8 | 1.00 | 8.50 | 6.00 | 2.12 | 4.00 |
| 6" | 14.00 | 1.88 | 8.50 | 12 | 1.12 | 11.50 | 8.75 | 2.62 | 4.62 |
| 8" | 16.50 | 2.19 | 10.62 | 12 | 1.25 | 13.75 | 10.75 | 3.00 | 5.25 |
| 10" | 20.00 | 2.50 | 12.75 | 16 | 1.38 | 17.00 | 13.50 | 3.38 | 6.00 |
| 12" | 22.00 | 2.62 | 15.00 | 20 | 1.38 | 19.25 | 15.75 | 3.62 | 6.12 |
| 16" | 27.00 | 3.00 | 18.50 | 20 | 1.62 | 23.75 | 19.50 | 4.19 | 7.00 |
| 20" | 32.00 | 3.50 | 23.00 | 24 | 1.75 | 28.50 | 24.00 | 5.00 | 7.50 |
| 24" | 37.00 | 4.00 | 27.25 | 24 | 2.00 | 33.00 | 28.25 | 5.50 | 8.00 |
Dimensional Engineering Data
ASME B16.5 Class 900, 1500 & 2500 Severe-Service Flanges
Dimensional criteria for critical high-pressure, extreme-temperature offshore and petrochemical piping systems.
| NPS (Inches) | Rating Class | OD (Inches) | Thickness T (Inches) | RF Dia R (Inches) | Bolt Holes | Hole Dia (Inches) | BC (Inches) | WN LTH WL (Inches) |
|---|---|---|---|---|---|---|---|---|
| 3" | Class 900 | 9.50 | 1.50 | 5.00 | 8 | 1.00 | 7.50 | 4.00 |
| 4" | Class 900 | 11.50 | 1.75 | 6.19 | 8 | 1.25 | 9.25 | 4.50 |
| 6" | Class 900 | 15.00 | 2.19 | 8.50 | 12 | 1.25 | 12.50 | 5.50 |
| 8" | Class 900 | 18.50 | 2.50 | 10.62 | 12 | 1.50 | 15.50 | 6.38 |
| 1" | Class 1500 | 5.88 | 1.12 | 2.00 | 4 | 1.00 | 4.00 | 2.88 |
| 2" | Class 1500 | 8.50 | 1.50 | 3.62 | 8 | 1.00 | 6.50 | 4.00 |
| 4" | Class 1500 | 12.25 | 2.12 | 6.19 | 8 | 1.38 | 9.50 | 4.88 |
| 6" | Class 1500 | 15.50 | 3.25 | 8.50 | 12 | 1.50 | 12.50 | 6.75 |
| 1" | Class 2500 | 6.25 | 1.38 | 2.00 | 4 | 1.00 | 4.25 | 3.50 |
| 2" | Class 2500 | 9.25 | 2.00 | 3.62 | 8 | 1.12 | 6.75 | 5.00 |
| 3" | Class 2500 | 12.00 | 2.62 | 5.00 | 8 | 1.38 | 9.00 | 6.62 |
| 4" | Class 2500 | 14.00 | 3.00 | 6.19 | 8 | 1.62 | 10.75 | 7.50 |
Tolerance & Quality Control
Manufacturing Dimensional Tolerances (ASME B16.5)
Strict quality-controlled dimensional limits strictly adhered to during CNC machining and coordinate measuring machine (CMM) inspections.
| Dimension Feature | Size Category | Allowable Tolerance Limit |
|---|---|---|
| Outside Diameter (OD) | NPS ≤ 24" | ±1.6 mm (±0.06 in.) |
| Inside Bore Diameter (WNRF) | NPS ≤ 10" NPS 12" to 18" NPS ≥ 20" | ±0.8 mm (±0.03 in.) ±1.6 mm (±0.06 in.) +3.2 mm / -1.6 mm (+0.12 in. / -0.06 in.) |
| Raised Face Diameter | 1/16" Raised Face (Class 150/300) 1/4" RF, RTJ, T&G Groove | ±0.8 mm (±0.03 in.) ±0.4 mm (±0.016 in.) |
| Flange Thickness (T) | NPS ≤ 18" NPS ≥ 20" | +3.2 mm / -0 mm (+0.12 in. / -0 in.) +4.8 mm / -0 mm (+0.19 in. / -0 in.) |
| Bolt Circle Drilling | Bolt Circle Diameter Adjacent Bolt Hole Spacing | ±1.6 mm (±0.06 in.) ±0.8 mm (±0.03 in.) |
Bolting & Assembly Guide
Stud Bolt & Machine Bolt Dimensions for ASME B16.5 Flanges
Guide for sizing high-tensile ASTM A193 B7 stud bolts, ASTM A194 2H nuts, and gasket sealing dimensions across standard classes.
| NPS (Inches) | Class 150 Studs (Dia × Len) | Class 300 Studs (Dia × Len) | Class 600 Studs (Dia × Len) | Gasket ID (Inches) | Gasket OD Class 150 | Gasket OD Class 300 |
|---|---|---|---|---|---|---|
| 1/2" | 4 × (1/2" × 2.25") | 4 × (1/2" × 2.50") | 4 × (1/2" × 3.00") | 0.84 | 1.88 | 2.12 |
| 3/4" | 4 × (1/2" × 2.50") | 4 × (5/8" × 2.75") | 4 × (5/8" × 3.50") | 1.06 | 2.25 | 2.62 |
| 1" | 4 × (1/2" × 2.50") | 4 × (5/8" × 3.00") | 4 × (5/8" × 3.50") | 1.31 | 2.62 | 2.88 |
| 1-1/2" | 4 × (1/2" × 2.75") | 4 × (3/4" × 3.50") | 4 × (3/4" × 4.25") | 1.91 | 3.38 | 3.75 |
| 2" | 4 × (5/8" × 3.25") | 8 × (5/8" × 3.50") | 8 × (5/8" × 4.25") | 2.38 | 4.12 | 4.38 |
| 3" | 4 × (5/8" × 3.50") | 8 × (3/4" × 4.25") | 8 × (3/4" × 5.00") | 3.50 | 5.38 | 5.88 |
| 4" | 8 × (5/8" × 3.50") | 8 × (3/4" × 4.50") | 8 × (7/8" × 5.75") | 4.50 | 6.88 | 7.12 |
| 6" | 8 × (3/4" × 4.00") | 12 × (3/4" × 4.75") | 12 × (1" × 6.75") | 6.62 | 8.75 | 9.88 |
| 8" | 8 × (3/4" × 4.25") | 12 × (7/8" × 5.50") | 12 × (1-1/8" × 7.75") | 8.62 | 11.00 | 12.12 |
| 10" | 12 × (7/8" × 4.50") | 16 × (1" × 6.25") | 16 × (1-1/4" × 8.50") | 10.75 | 13.38 | 14.25 |
| 12" | 12 × (7/8" × 4.75") | 16 × (1-1/8" × 6.75") | 20 × (1-1/4" × 8.75") | 12.75 | 16.12 | 16.62 |