Introduction to Butt-Weld Flanges

　　Butt-weld flanges are pipe fittings with a neck and a circular tube transition structure. They are connected to pipelines by welding and are mainly used in high-pressure, high-temperature, or media-sensitive piping systems. Their flared neck structure keeps the weld joint away from the sealing surface, reducing welding deformation and improving sealing performance. Applicable pressure ratings range from PN2.5MPa to PN400 and higher.

　　The flanges are made of more than 20 materials, including carbon steel, stainless steel, and nickel alloys. Manufacturing processes include forging, casting, cutting, and rolling. Forged flanges, due to their excellent mechanical properties, are often used in high-stress environments; cast flanges are suitable for producing low-cost, complex components. Products undergo ultrasonic testing and post-weld heat treatment for quality control.

　　Butt-weld flanges are marked with pressure ratings from DN to PN (e.g., DN80-PN40). Their sealing surface types include six types, such as raised face and recessed face, and they are secured with bolts and gaskets to achieve a seal. They are widely used in valve and pipeline connections in the petroleum, chemical, and power industries, and are particularly suitable for conveying flammable and explosive media or in conditions with large temperature fluctuations.

　　Butt-weld flanges are not easily deformed, have good sealing properties, and are widely used. They have corresponding rigidity and elasticity requirements and reasonable butt welding thinning transition. The distance between the weld and the joint surface is large, and the joint surface is not affected by welding temperature deformation. They adopt a relatively complex horn-shaped structure and are suitable for pipelines with large pressure or temperature fluctuations or high temperature, high pressure and low temperature pipelines. They are generally used for the connection of pipelines and valves with PN greater than 2.5MPa; they are also used in pipelines that transport expensive, flammable and explosive media.