Product Introduction

National standard butt welding flange is a butt welding flange that complies with Chinese national standards (GB series). It is a pressure bearing pipe fitting used to connect pipelines, valves, and equipment in pipeline systems. Its core feature is that it is connected to the pipeline as a whole through welding, with high sealing performance and pressure resistance level.

Core Features

The structural characteristics of the national standard welded flange generally have a long neck (also known as a "high neck"), one end of which is connected to the flange body, and the other end is matched with the outer diameter of the pipeline. It is connected by groove welding, and the weld quality is easy to detect, which can withstand higher pressure and temperature. Compared to flat welding flanges, its neck can enhance the rigidity of the flange and reduce deformation caused by stress concentration after welding.

Execution standard

The commonly used national welding flange standards in China include:

GB/T 9115: Core standard for steel butt welded flanges, covering flange specifications of different pressure levels (such as PN10, PN16, PN25, PN40, etc.) and nominal diameters (DN10~DN2000).

It will also be accompanied by standards such as GB/T 9124 (Technical Conditions for Flanges), which specify requirements for materials, dimensional tolerances, sealing surface forms, etc.

Various types

The sealing surface form varies depending on the usage scenario, and there are multiple types of sealing surfaces for national standard welded flanges:

RF: The most commonly used, suitable for medium and low pressure, non corrosive or weakly corrosive media.

Concave convex surface (MFM), tenon groove surface (TG): better sealing performance, suitable for flammable, explosive, toxic media or high-pressure working conditions.

Full Flat (FF): Generally used in situations where low pressure and low leakage are required.

Due to its excellent pressure resistance, temperature resistance, and sealing performance, it is commonly used in pipeline systems for high temperature and high pressure, flammable and explosive, toxic and harmful media, such as petrochemical, power, metallurgical, natural gas transportation and other industries.