Butt welding flange

A butt welding flange (also called a weld-neck flange) is a type of pipe flange designed to be welded to a pipe or fitting using a butt weld (a circumferential weld around the neck of the flange). It is widely used in high-pressure and high-temperature piping systems due to its strength, durability, and leak-proof connection.

Key Features of Butt Welding Flanges

1. Weld Neck Design
   • Has a tapered hub that provides reinforcement and reduces stress concentration.
   • The smooth transition from flange thickness to pipe wall thickness improves flow characteristics.
2. High Strength & Durability
   • Suitable for extreme conditions (high pressure, high/low temperature, corrosive environments).
   • Commonly used in oil & gas, chemical plants, power generation, and shipbuilding.
3. Leak-Resistant Connection
   • The butt weld ensures a strong, permanent joint with minimal risk of leakage.
4. Compatibility with Various Standards
   • ASME/ANSI B16.5 (Standard for flanges up to 24″)
   • ASME B16.47 (Large-diameter flanges)
   • EN 1092-1 (European standard)
   • MSS SP-44, API 6A (Specialized applications)

Types of Butt Welding Flanges

Materials Used

Butt welding flanges are available in various materials, including:

• Carbon Steel (ASTM A105) – General-purpose use.
• Stainless Steel (SS 304, SS 316) – Corrosion-resistant applications.
• Alloy Steel (ASTM A182 F11, F22) – High-temperature & high-pressure services.
• Duplex & Super Duplex (UNS S31803, S32750) – Extreme corrosion resistance.

Advantages Over Other Flange Types

✔ Stronger than slip-on or socket weld flanges (better for high-pressure systems).
✔ Better fatigue resistance due to the tapered hub.
✔ Smoother fluid flow (no internal crevices).
✔ Longer service life in harsh conditions.

Common Applications

• Oil & Gas Pipelines
• Chemical & Petrochemical Plants
• Power Generation (Steam, Boilers)
• Water Treatment Systems
• Shipbuilding & Offshore Platforms

Conclusion

Butt welding flanges are essential for high-integrity piping systems where strength, durability, and leak-proof performance are critical. Their design ensures reliable performance in demanding industrial environments.

Mila