The Basics In Manufacturing Seamless Steel Pipe

by | Jul 9, 2015 | Construction & Maintenance

There are two different methods used in the manufacturing of steel pipe. The most common and the oldest is the welded pipe method. The other option available today is the seamless steel pipe.

To understanding the difference in the two, which is more than just a weld or produced without a weld, it is important to take a look at the processing of the alloy and how the two manufacturing processes differ.

Welded Pipe

All pipe in any form starts as a block of metal which is a mixture of iron ore and coke. It has been formed into an ingot, which may also be called a billet, and these will weigh tons.

This large ingot or billet is then placed in a furnace where it is heated again, just to the point of being plastic-like but not liquid. At this point, for a welded pipe, the now soft steel is rolled to a specified thickness with flat rollers. The result is a uniformly thick flat sheet of steel.

This sheet is then cut, all using precision cutting equipment and then rolled again through grooved rollers to create the perfectly round shape. It then goes along a conveyor system and passes under welding electrodes and another roller to ensure the weld is tight.

Seamless Steel Pipe

There are two different options in making seamless steel pipe. The most common is the rotary piercing and rolling method. In this method, the steel is heated and rolled around a central piercer point, resulting in a hollow tube in the middle where the piercer is located.

This hollow piece is then rolled through a series of mills that stretch the billet, creating the specific size of seamless steel pipe required. Initially, there is a plug in place but once the interior shape is formed the rolling is completed without the plug.

Another option is the extrusion process, where the steel is heated and forced through a die under very high pressure. The pipe is produced continually, and can be manufactured to industry standards and tolerances or those specified by the customer.

There are many steps involved in creating both welded and seamless steel pipe. The most important factor is to work with an industry leading supplier to ensure you are getting top quality pipe manufactured with any special requirements you may need.

Kelly Pipe provides a top selection of welded and seamless steel pipe for all industries and applications. To see more go to

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