Tianjin United Steel Pipe Co., Ltd

Difference between Seamless and Welded Steel Pipes and Tubes

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Courtesy of Tianjin United Steel Pipe Co., Ltd

Pipes are usually produced by two distinct methods which are a welded pipe or a seamless pipe. In both methods, raw material is first cast into ingots. It is then made into a pipe by stretching the steel out into a seamless tube or forcing the edges together and sealing them with a weld.

The following are the main differences between seamless and welded pipes.

·         Seamless pipes don’t have a weld seam. Traditionally, the seam of welded pipes has been viewed as a weak spot, vulnerable to failure and corrosion. However, improvements in the manufacturing process for welded pipes have increased the strength and performance of the weld seam. Still seamless pipes prevent any possibility of a weak seam. In general, welded steel pipes can withhold 20% less working pressure than seamless.

·         Seamless pipes has higher working pressures compared to welded pipes of the same material and size due to having no welded seam.

·         Seamless pipes offers superior corrosion resistance because it has little potential for impurities, defects and differences in malleability that may be associated with the welded area in welded pipe.

·         Seamless pipes do not require testing for weld integrity. This is a must for welded pipes.

·         The cost of welded pipes is cheaper than seamless pipes and is readily available in long continuous lengths.

·         Seamless pipes can be substituted for welded pipe but welded pipes may not always be able to be substituted for seamless pipe due to the weld seam.

·         The wall thickness of welded pipes is generally more consistent than that of seamless pipes. It is easier to get a uniform thick flat strip and produce a welded pipe than drawing a uniformly thick seamless pipe through extrusion. Also welded pipes surface finish quality is much better than seamless pipes.

·         Longer procurement lead time is required for seamless pipes as compared to welded pipes.