Home Knowledge Installations & materials The difference between seamless pipe and seamed pipe

The difference between seamless pipe and seamed pipe

Seamless steel tubes are formed at one time during rolling. Welded steel pipes need to be welded after rolling, generally with spiral welding and straight welding. The performance seamless tube is better, and of course the price is higher.

Steel pipe is a kind of hollow long steel, which is used as a pipeline for conveying fluids, such as petroleum, natural gas, water, gas, steam, etc. In addition, when the bending and torsional strength are the same, the weight is light, so it is also widely used. Used in the manufacture of mechanical parts and engineering structures. Also used to produce a variety of conventional weapons, barrels, shells and so on.

Types of steel pipes

Steel pipes are classified into two types; Seamless steel pipes and welded steel pipes according to their manufacturing methods. The seamless steel pipe is made of high-quality carbon steel or alloy steel and has hot rolling and cold rolling (extraction).

The welded steel pipe is formed by welding a steel plate rolled into a tubular shape by a seam or a spiral seam. In terms of the manufacturing method, it is further divided into a welded steel pipe for low-pressure fluid transportation, a spiral-welded electric steel pipe, a direct-wound welded steel pipe, an electric welded pipe, and the like. Seamless steel tubes can be used in a variety of liquids, gas pipelines, and the like. Welded pipes can be used for water pipes, gas pipes, heating pipes, etc.

Processing form

Slotted steel pipes and seamless steel pipes are divided according to the processing form. The seamed steel pipes are generally welded. The seamless steel pipes are cold drawn and hot-rolled. The carbon steel pipes are in terms of materials, and the galvanized pipes are welded pipes. After the surface is galvanized again.

Welded steel pipes, such as tap water pipes, are usually welded by bending the flat material, and a weld seam can be found on the above; the coarser diameter is generally a spiral weld.The seamless steel pipe is generally formed by laminating molten steel in a molten state through a ring slit and then being subjected to a stretching process, so that there is no weld. In terms of performance, especially the pressure bearing capacity is greatly improved compared with ordinary steel pipes, so it is often used on high-voltage equipment.

The weld joint of welded steel pipe is the weak link, and the weld quality is also the main factor affecting its overall performance. People who have lived in the north generally have experienced the experience of freezing water pipes or heating pipes in the winter. The places where the explosions are usually welded. Generally speaking: the carrier requires high requirements such as pressure, environment, maintenance, corrosion, and temperature. Use seamless steel pipe; for seams with low pressure and temperature requirements. Such as living water pipes, gas pipes.


  1. I really like that you touched on how the seamed steel pipes are generally welded together. My brother is trying to start a new business this year that will need to use a lot of these steel pipes. I’ll share this article with him so that he can understand what pipes he should be using more.

  2. It is really interesting how these two different styles of pipes are both formed from steel. Since welded pipes have a weak spot, it makes sense that you wouldn’t want to use them under high-pressure situations. Since I need to replace the plumbing in my home, I think I will choose the seamless option in that case.


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