ASME B16.5 Pipe Flanges
Standard: ASME B16.5 (NPS 1/2″ – 24″)
Pressure Classes: 150, 300, 600, 900, 1500, 2500
Material Grades: Carbon Steel (A105, LF2), Stainless (304/316L), Alloy Steel (F11/F22)
Flange Types: Weld Neck, Slip-On, Blind, Socket Weld, Threaded, Lap Joint
Surface Finish: Standard RF (125-250 AARH), RTJ, or Smooth Finish
Certification: EN 10204 3.1 MTR, ISO Certified Quality Control
Lead Time: Large stock available for standard sizes; custom forging supported
Production Description
ASME B16.5 Forged Pipe Flanges
NPS 1/2″ Through NPS 24″ | Global Standard Forged Steel Flanges
Technical Scope & Standards
The ASME B16.5 standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges and flanged fittings. As a core component in high-pressure piping systems, these flanges are manufactured via integrated forging processes to ensure structural integrity and leak-proof performance.
- Size Range: NPS 1/2″ to NPS 24″ (DN15 – DN600)
- Pressure Classes: 150, 300, 400, 600, 900, 1500, 2500
- Manufacturing: Forged, Heat Treated
- Facing: Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ)
Common ASME B16.5 Flange Types
Best for high-pressure, extreme temperatures and severe stress cycles.
Easy to align, lower installation cost for moderate pressure service.
Used to seal the end of piping systems or pressure vessel openings.
Ideal for small-diameter, high-pressure piping systems.
Fast connection for low-pressure systems where welding is hazardous.
Used with stub ends for systems requiring frequent cleaning or inspection.
Material Grades & Material Selection
| Steel Type | Standard ASTM / ASME Grades |
|---|---|
| Carbon Steel | ASTM A105, ASTM A350 LF2 (Low Temp), ASTM A694 F42-F70 |
| Stainless Steel | ASTM A182 F304/304L, F316/316L, F321, F347 |
| Alloy Steel | ASTM A182 F1, F5, F9, F11 Class 2, F22 Class 3 |
ASME B16.5 Class 300 Dimensional Data (Reference)
| NPS | Flange OD | Thickness (Min) | Bolt Circle | Bolt Hole Qty | Bolt Hole Dia |
|---|---|---|---|---|---|
| 1/2″ | 3.75″ | 0.50″ | 2.62″ | 4 | 0.62″ |
| 1″ | 4.88″ | 0.69″ | 3.50″ | 4 | 0.75″ |
| 2″ | 6.50″ | 0.81″ | 5.00″ | 8 | 0.75″ |
| 4″ | 10.00″ | 1.19″ | 7.88″ | 8 | 0.88″ |
*All dimensions conform to ASME B16.5 standards. Full dimensional charts available upon request.
Quality Control & Inspection
1. Flange Facing Surface Finish (AARH)
Standard finishes for Raised Face (RF) flanges are 125–250 µin AARH (Arithmetic Average Roughness Height). For special gas services, custom smooth finishes can be provided.
2. Visual and Dimensional Examination
Strict adherence to tolerances for bolt hole alignment, perpendicularity of the face to the bore, and hub dimensions is mandatory for all our production.
3. Traceability and MTRs
Every shipment includes EN 10204 3.1 Mill Test Reports (MTRs) detailing chemical composition, tensile strength, yield strength, elongation, and hardness values.
Why Source From RAYOUNG ?
FAQs
Q: What sizes do Class 150 flanges come in?
A: ASME B16.5 covers Class 150 flanges from NPS 1/2″ through 24″. For larger diameters, the equivalent standard is ASME B16.47 Series A and B.
Q: What is the difference between Class 150 and Class 300?
A: Class 300 carries a higher pressure rating than Class 150 (740 psi vs 285 psi at 100°F in A105) and uses a thicker flange with a different, non-interchangeable bolt pattern. Choose the class from the pressure-temperature rating your service requires.
Q: How many bolts does a Class 150 flange use?
A: It depends on the size. ASME B16.5 bolt-hole counts are always a multiple of four, from 4 bolts on small sizes up to 20 on a 24″ flange. See our flange bolt chart for the exact bolt count, size, and bolt circle for each diameter.
Procurement & Inquiry Support
NPS 1/2″ to 24″ | Stockist Pricing | Material Certification Guaranteed
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