Understanding ASME ANSI B16.5 Flange Types-A Quick Technical Guide
author: www.qishine.com
2025-12-13
In piping systems, selecting the right flange is crucial for safety and compliance.
COMMON FLANGES – Applications & Specs
✅ Weld Neck Flange
Tapered hub for stress distribution
Ideal for high-pressure/temperature systems (up to 2500 psi, ~1500°F)
Butt-welded to pipe; ensures strong, fatigue-resistant joints
Tapered hub for stress distribution
Ideal for high-pressure/temperature systems (up to 2500 psi, ~1500°F)
Butt-welded to pipe; ensures strong, fatigue-resistant joints
✅ Slip-On Flange
Slides over pipe +inner and outer fillet welding
Lower cost & easier alignment; suitable for moderate pressure (≤1500 psi)-Not recommended for severe cyclic loading
✅ Socket-Weld Flange
Pipe inserted into socket + external weld only
Suitable for small-bore, high-pressure lines (e.g., instrumentation)
Avoid in corrosive/erosive service due to crevice corrosion risk
✅ Threaded Flange
NPT or BSP threads; no welding required
Used in low-pressure systems, hazardous zones, or where hot work is restricted-Limited to ≤1000 psi depending on material & size
✅ Lap-Joint Flange
Pairs with Stub End; allows easy bolt-hole alignment & dismantling
Ideal for systems requiring frequent maintenance; flange itself is not welded
Material flexibility — flange can be carbon steel, Stub End corrosion-resistant
✅ Blind Flange
Solid disc for system isolation, pressure testing, or future expansion
Rated to match mating flange pressure class (150# to 2500#)
Solid disc for system isolation, pressure testing, or future expansion
Rated to match mating flange pressure class (150# to 2500#)
⚙️ SPECIALIZED TYPES – For Demanding Applications
▪️ Long Weld Neck Flange
Extended neck for heavy-wall vessel nozzles, high thermal cycling, and severe service
Extended neck for heavy-wall vessel nozzles, high thermal cycling, and severe service
▪️ Reducer / Expander / Swivel Flanges
For line size changes or rotating alignment during bolt-up
For line size changes or rotating alignment during bolt-up
▪️ Orifice & Nipo Flanges
Designed for metering, instrumentation, and branch connections
Designed for metering, instrumentation, and branch connections
▪️ Vacuum Flanges (KF/QF, ISO, CF)
Used in high-vacuum systems (labs, semiconductor, space simulation)
Used in high-vacuum systems (labs, semiconductor, space simulation)
Key Selection Criteria – Remember These!
▪️ Match flange pressure class (150#, 300#, 600#, etc.) to design conditions
▪️ Ensure face type compatibility (RF, FF, RTJ)
▪️ Verify material grade (A105, F304, F316, etc.) for temperature & corrosion resistance
▪️ Follow ASME B16.5 for dimensions, tolerances, and marking requirements
▪️ Ensure face type compatibility (RF, FF, RTJ)
▪️ Verify material grade (A105, F304, F316, etc.) for temperature & corrosion resistance
▪️ Follow ASME B16.5 for dimensions, tolerances, and marking requirements
Summary
While the six common types cover most industrial needs, specialized designs address niche challenges. Compliance with ASME/ANSI B16.5 ensures system integrity, safety, and global interoperability.
While the six common types cover most industrial needs, specialized designs address niche challenges. Compliance with ASME/ANSI B16.5 ensures system integrity, safety, and global interoperability.
Qishine is ideal choice for EPC companies and project contractors.
Website: www.qishine.com
Email: qishine@qishine.com
Tel: 0592-5225595
WhatsApp: +86 15960259563
+86 15985833169
Website: www.qishine.com
Email: qishine@qishine.com
Tel: 0592-5225595
WhatsApp: +86 15960259563
+86 15985833169
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