It is a very complicated process to select welded pipes, welded drawn pipes, and seamless pipes according to the application site.
The seamless pipe can provide higher corrosion resistance, because it can achieve a 100% seamless state, without any longitudinal or orbital welds.
Longitudinal welds are one of the potential sources of defects, which must not appear in key applications. In the production of welded pipes, a flat steel strip should be rolled and connected to the longitudinal seam. The process can be performed by laser centering or argon arc welding. Since the welded area is not consistent with the steel strip in size, it will cause a stress concentration area, especially for pipe fittings that bear higher internal pressure.
In addition, the gaps existing on both sides of the weld will be likely to be corroded, and during the heat treatment, as the residue is captured, metallurgical contamination may cause corrosion. Such gaps can cause cracks, and the expansion of the latter can cause the welded pipe to rupture.
Some manufacturers have adopted different methods in an attempt to minimize dimensional changes and make the welds joined together, including seam welding, heat sink welding, float welding and plug welding.
Re-drawing the welded pipe through the die and plug, followed by annealing treatment will help maintain a uniform weld.
In order to keep the weld completely uniform, this type of operation needs to be repeated several times, thereby increasing the total cost.
In contrast, the weld under the seamless pipe is zero.
As a seamless pipe manufacturer, Huzhou Nanxun Yintuo Special Material Technology Co., Ltd. is committed to producing super austenitic stainless steel seamless pipe and tube. If you are interested in our products, you are welcome to contact us.