Large diameter elbow generally refers to more than DN600 caliber, large caliber, including large-diameter straight seam elbow elbow, elbow welded large diameter seamless elbow. Most used on the market is welded elbow, straight seam and seamless in terms of large-caliber technical equipment in addition to the raw materials, then there are expensive. Large diameter elbow angle can be divided according to a large-caliber elbow 45 degrees, 90 degrees and 180 degrees of large diameter elbow and other large-caliber elbow bend at different angles. According to the material can be divided into large diameter carbon steel elbow, elbow large diameter stainless steel, alloy steel large diameter elbow. According to the radius of curvature can be divided into long and short radius bend radius of large diameter large diameter elbow. Large diameter elbow main criteria GB, electricity standard, Sinopec standard, marine standard, Japanese standard, American standard and so on. Large diameter elbow with a smooth wall, heat medium flow resistance is small, acid, long life, easy installation. Seamless elbow pipe fittings for a turn at. All fittings in piping systems and more in use, the largest proportion, about 80%. Typically, the thickness of the goods of different materials to select a different bend forming process. For now. Manufacturers commonly seamless elbow push hot forming process, stamping, extrusion, etc. raw rolled seamless pipe elbow is round tube, tube embryos to go through cutting the growth of the cutting machine is about one meter blank, and sent to the furnace heating the conveyor belt. The billet is fed in the heating furnace, a temperature of about 1200 degrees Celsius. Furnace temperature control is a key issue. After the round tube came out to go through the pressure punching machine wear empty. Generally more common punch is tapered roller punching machine, punching machine such high production efficiency, product quality, perforated expanding capacity, can be worn a variety of pipe fittings. After perforation, round tube has been three-roll rolling, rolling or extrusion. To take off the tube after extrusion sizing. Sizing machine rotating at high speed into the embryo through a tapered drill steel perforated to form the tube.