National standard welded flanges are manufactured according to national standards. They have a neck and a circular pipe transition, and are used to weld flanges to pipes. They make pipe connections more stable and have better sealing performance. They are widely used in petroleum, chemical, natural gas, power plants, and metallurgical pipelines, suitable for pipelines with large pressure or temperature fluctuations, as well as high-temperature, high-pressure, and low-temperature pipelines. They are also used in pipelines transporting expensive, flammable, and explosive media.

Structural Features

Neck Design: It has a relatively long neck, which is welded to the pipe. The neck enhances the connection strength between the flange and the pipe, providing a smoother fluid passage and reducing fluid resistance.

Sealing Surface: Common sealing surface types include flat (FF), convex (RF), concave (FM), and tongue and groove (TG), etc. Different types are suitable for different sealing requirements and operating conditions.

Bolt Holes: Evenly distributed, used to connect with the mating flange through bolts and nuts. The number, size, and distribution position are in accordance with the standard to ensure the reliability and interchangeability of the connection.

Material Selection

Carbon Steel: Such as WCB, etc., has good strength and economy, suitable for pipeline systems in general industrial environments.

Stainless Steel: For example, 304, 316L, etc., has excellent corrosion resistance and oxidation resistance, often used in chemical, food, pharmaceutical and other industries with high corrosion resistance requirements.

Alloy Steel: Can meet the use requirements of high temperature and high pressure special working conditions, widely used in power, petrochemical and other fields.

Specifications and Dimensions

Size Range: The nominal diameter is usually DN10 - DN2000 and other specifications, which can meet the different needs of small-diameter to large-scale industrial pipelines.

Pressure Level: Includes PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN320, PN420, etc. Different pressure levels correspond to different application scenarios and pipeline system requirements.

Manufacturing Standards

Relevant national standards include GB/T9115.1 - 2000, GB/T9115.2 - 2000, GB/T9115.3 - 2000, GB/T9115.4 - 2000, etc., which specify the design, dimensions, material selection, manufacturing process, inspection methods, and marking requirements of national standard welded flanges to ensure product quality and interchangeability.

Product Features

High Connection Strength: The welding connection method makes the flange and pipe connection firm, capable of withstanding high pressure and tensile force.

Good Sealing Performance: With appropriate sealing gaskets, good sealing effect can be achieved, reducing the possibility of media leakage.

Strong Anti-deformation Ability: It has corresponding rigidity and elasticity requirements, and has reasonable welded thinning transition, not easy to deform, and can adapt to different working environments.

Beautiful Appearance: The surface is smooth and flat, after mechanical processing and treatment, the appearance quality is good.

Application Fields

Wind Power Industry	Shipbuilding	Mechanical Manufacturing
Nuclear Power Industry	Oilfield Industry	Chemical Industry