Large Diameter Weld Neck Flange

The Large Diameter Weld Neck Flange is engineered for large bore pipeline systems that demand a strong, reliable connection at high flow rates. Produced from forged carbon steel, stainless steel and alloy steel billets, these oversized flanges maintain dimensional accuracy and mechanical integrity even at diameters up to 72 inch, making them ideal for main trunk lines, water transmission and major industrial piping.

Manufactured to ASME B16.5 and ASME B16.47 standards, each large diameter weld neck flange undergoes precision machining to guarantee flatness of the sealing face and concentricity of the bolt circle. The extended weld neck hub provides a gradual transition that supports full penetration butt welding, minimizing stress at the joint and delivering a leak-tight seal under sustained operating pressure.

Product Specifications

Key Advantages

• Available in diameters from 24 inch up to 72 inch
• Precision machined sealing face for leak-tight performance
• Full penetration butt weld hub for high joint strength
• Forged billet construction ensures uniform mechanical properties
• Dimensional control to ASME B16.5 and B16.47 tolerances
• Custom face drilling and bolt circle patterns available
• Suitable for high flow main trunk lines and transmission systems
• Complete traceability with mill test certificates

Frequently Asked Questions

Q: What is the maximum diameter available for a large diameter weld neck flange?

A: We manufacture large diameter weld neck flanges up to 72 inch. For diameters beyond 48 inch, flanges are typically supplied as custom-forged rings machined to ASME B16.47 Series A or Series B dimensions according to your piping specification.

Q: How do you ensure flatness on a large diameter sealing face?

A: Each large diameter weld neck flange is precision machined on large-bore CNC lathes and verified with a coordinate measuring machine. The raised face is machined with a controlled surface finish to ensure a reliable gasket seal under operating pressure.

Q: Can you produce large diameter flanges with custom bolt patterns?

A: Yes, we offer custom face drilling and bolt circle patterns to match non-standard mating equipment. Simply provide your drawing or specification, and our engineering team will confirm feasibility and lead time.

Manufacturing & Quality Control

Large diameter weld neck flanges are forged from carefully selected billets and machined on large-bore CNC turning centers. After machining, the sealing face flatness and bolt circle concentricity are verified with a coordinate measuring machine to ensure perfect alignment with mating equipment. Each flange is marked with heat number, material grade and pressure class for full traceability from billet to finished product.

Q: How are large diameter flanges packed and shipped?

A: Large diameter weld neck flanges are packed on reinforced steel pallets with protective edge guards and weather-resistant wrapping to prevent damage during transport. We coordinate with ocean freight and land carriers experienced in oversized cargo to deliver your flanges safely to the project site.