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    Butt Weld Pipe Fittings Selection: Seamless or Semi-Seamless(Welded)

    Introduction of manufacturers of butt weld pipe fittings

    Mengcun county, Hebei province, China, "the hometown of elbow and pipe fittings", where our own manufacturing center is located, has more than 1000 factories of butt weld pipe fittings. It is reported that almost 68.6% of world's carbon steel butt weld pipe fittings are fabricated here in China. Various elbows, tees, reducers, crosses and end caps are manufactured and delivered to Middle East, South & North America, Southeast Asia, Europe and Africa every day meeting a comprehensive range of international standards such as ASME B16.9, EN10253, JIS B2312, JIS B2313, JIS B2220, JIS B2202, JIS G3459, JIS B2309 and GOST, etc. Hebei Metals Industrial Limited has the production capability of pipe fittings sized from 1/2" to 96" with the wall thickness from 1.2mm to 207mm.

    Seamless or Semi-Seamless(Welded) butt weld pipe fittings

    During the procurement of pipe fittings, many foreign customers may be confused by the description of "seamless" and "semi-seamless". "Seamless" refers to pipe fittings made from seamless steel pipes while "Semi-Seamless" refer to those made from welded steel pipes with weld seam removed. The semi-seamless looks like real seamless especially after sand blasting surface treatment but it is actually welded. The two photos below shows slight difference between seamless and semi-seamless elbows: there is a slightly shallow dent-strip on the side-arc surface of the elbow. Because the weld seam area has quite different physical & mechanical properties from its adjacent carbon steel area, when the welded pipe segment is pushed through the mid-frequency induction machine to form a elbow, the two areas are deformed quite differently and it can't form a uniform and smooth cambered surface. When it comes to pipe tee or pipe reducer, technically most factories will machine out the internal surface of the finished fittings. In that case, even experienced engineers can't distinguish semi-seamless from real seamless visually. 
    Real Seamless Butt Weld Elbow
    Semi-Seamless(Welded) Butt Weld Elbow

    Advantages & disadvantages of "Seamless" compared with "Semi-Seamless(Welded)"

    Semi-Seamless(Welded), since it is made from welded pipes, has a much lower price. And because weld pipes are made of steel plates, usually semi-seamless pipe fittings have an uniform wall thickness except for the weld seam area. We always suggest real seamless for all pipe fittings equal to or smaller than 24". The advantages of real seamless are apparent,
    1) Real seamless has more excellent mechanical properties hence can withstand much higher pressure.
    2) No need of X-Ray inspection on the weld seam.
    3) Long lifespan and safety assurance.

     

    Views: 10582  Author:METALS INDUSTRIAL  Date:2015/02/17