There are many kinds of elbows, as a leading manufacturer and exporter, Great Steel Pipe provides three kinds of steel pipe elbow for customer to choose, including carbon steel, stainless steel, and alloy steel. Among them, carbon steel elbow also includes seamless elbow and welded elbow. Next, Prime Steel Pipe will share the manufacturing process of seamless elbow and welded elbow for all of you. If you need to purchase elbow, Great Steel Pipe must be your best choice.
Manufacturing Process of Seamless Elbow
The manufacturing process of seamless elbow usually contains heating bending and clod bending. One of the most common methods is using hot mandrel bending from straight steel pipes. Applying hot mandrel bending can manufacture a wide size range seamless elbows. After heating the steel pipe at a elevated temperature, the pipe is pushed, expanded, bended by the inner tools of mandrel step by step.
When compared to other bending method type the advantages of hot bending elbows include smaller thickness deviation and stronger bending radius. Meanwhile, using bending instead of prefabricated bends substantially reduces the number of welds needed. This reduces the amount of work required and increases the quality and usability of pipes.
Cold bending is a quick and inexpensive bending method. It is a competitive option for making pipelines and machine parts. Cold bending is the process to bent the straight steel pipe at normal temperatures in a bending machine. Cold bending is suitable for pipes with an outer diameter of 17.0 to 219.1 mm, and wall thickness 2.0 to 28.0 mm. The recommended bending radius is 2.5 x Do. Normally at a bending radius of 40D. By using cold bending, we can get small radius elbows, but we need to pack the internals with sand to prevent wrinkling.
Manufacturing Process of Welded Elbow
Welded elbows are made from the steel plates, so there is a weld seam on it. Use a mould and press the steel plate to the shape of the elbow, then weld the seam to be a finish steel elbow. It is the old production method of the elbows. Recent years the small sizes elbows are almost manufactured from the steel pipes now. For the big size elbows, for example, it is very difficult to produce elbows over 36'' OD from the steel pipes . So it is commonly made from the steel plates, pressing the plate to the shape of half elbow, and welding the two halves together. Since the elbows are welded in its body , the inspection of the welding joint is necessary . Commonly we use the X-Ray inspection as the NDT.