Set up in 1995, Tonglu Valves Manufactring Co.,Ltd. is one of the leading China weld neck flange manufacturer and supplier in Yongjia County of Zhejiang Province. We manufacture all products strictly conforming to the API, JIS, ANSI, BS, GB, NF and DIN standards. Our oem weld neck flanges are available to users on request and are used for municipal works, petroleum, chemical industry, power station, metallurgy, national defense, and scientific research fields.

Weld neck Flanges are drilled (machined) with the wall thickness of the flange having the same dimensions of the matching pipe. The lighter the pipe is, the larger the bore, conversely, the heavier the pipe, the small the bore. They are normally used for high-pressure, cold or hot temperature. Flanges 1/2" to 24" and up to 450 lbs to BS10 Table D & Table E, BS Table F & Table H, BS Table J & Table K. We can also manufacture in different shapes and sizes depending upon your purpose. Flanges are confined to special applications. Their chief merit lies in the fact that they can be assembled without welding this explains their use in extremely high pressure services, particularly at or near atmospheric temperature, where alloy steel is essential for strength and where the necessary post weld heat treatment is impractical. flanges are unsuited for conditions involving temperature or bending stresses of any magnitude, particularly under cyclic conditions.

Welding neck flanges are distinguished from other types by their long tapered hub and gentle transition of thickness in the region of the butt weld joining them to the pipe. The long tapered hub provides an important reinforcement of the flange proper from the standpoint of strength and resistance to dishing. The smooth transition from flange thickness to pipe wall thickness effected by the taper is extremely beneficial under conditions of repeated bending, caused by line expansion or other variable forces and produces an endurance strength of welding neck flanged assemblies equivalent to that of a butt welded joint between pipes, which, in practice, is the same as that of unwelded pipe. Thus this type of flange is preferred for every severe service condition, whether this results from high pressure or from sub-zero or elevated temperature, and whether loading conditions are substantially constant or fluctuate between wide limits.

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