Why are Seamless Pipes more Expensive than Welded Pipes?

What is a seamless pipe?

Seamless pipe (SMLS) is a long strip of steel with a hollow section and no seams around it. The main feature is seamless welding. It is made by hot rolling, cold rolling or cold drawing, and has very high reliability and durability. Its advantages are high temperature resistance, good toughness, long pipe and few interfaces, and it is generally used as a fluid pipeline for special environments such as high pressure resistance and high temperature resistance. The disadvantages are high price, easy corrosion and short service life.

What is a welded pipe?

Welded pipe refers to a steel pipe with seams on the surface that is welded after bending and deforming a steel strip or steel plate into a circle, square, etc. The main feature is that there are seams. The blank used is steel plate or strip steel. It has strong corrosion resistance, high temperature resistance, long service life and low cost, and is usually used as a low-pressure fluid delivery pipeline. The disadvantage is that thicker iron plates cannot be welded and continuous welding is not possible, and the welding strength is low. It is difficult to weld workpieces with sealing and pressure requirements.

Because of its thin material and simple production process, its price is relatively low, and it is suitable for some occasions that do not require so much material. Welded pipes can be divided into straight seam (LSAW/ERW Welded Pipe) welded pipes and spiral welded pipes (SSAW) according to the shape of the weld seam.

Seamless Pipe vs. Welded Pipe Price

Generally speaking, the price of seamless steel pipes is higher than that of welded pipes. The main reasons why the price of seamless pipes is higher than that of welded pipes are as follows:

1. Production Process

Due to the relatively high production process requirements and many processes for manufacturing seamless steel pipes, the process cost increases.

The raw material of seamless steel pipe is round steel. Good round steel grades, especially tube blank steel, have less impurities and good forging effects, so the yield will naturally be higher. Seamless steel pipes are formed in one step during the rolling process. The processing of seamless steel pipes has been changed from solid round steel to hollow round bars. During the piercing process, cutting and high temperatures are required. During the pickling process, wastewater and slag need to be treated. In the annealing process, natural gas, etc. are used, and each process requires post-processing, which also consumes a lot of money.

Welded pipe is a steel pipe made of steel plate or strip welded by curling. Generally, spiral welding and direct welding are used. The production process is simple, the production efficiency is high, there are many varieties and specifications, the equipment investment is small, and the price is cheap. Seamless steel pipes have good pressure resistance, and welded pipes are generally around 10 MPa. Seamless pipes have better performance, but of course the price is higher. Seamless steel pipes of different materials can be used in many fields and have a wide range of applications.

2. Quality requirements

Seamless steel pipes have higher quality requirements. They need to ensure that there are no internal defects, a smooth appearance, and no burrs. Therefore, the requirements for raw materials and precision processing are higher, and the cost is correspondingly higher.

Although the price of welded pipe is relatively lower, due to the existence of its weld seam, cracks and brittle cracks are prone to appear at its interface, which affects its service life and safety.

3. Service life

The material of the seamless steel pipe is more uniform and compact, and its compressive and tensile strength indicators are higher than those of the welded pipe, so its service life is longer and more stable.

4. Market demand

Market demand and application scenarios of seamless pipes and welded pipes:

Finally, the market demand for seamless steel pipes is relatively small, and they are mainly used in fields that require high material quality, such as aviation and chemical industry. The market demand for welded pipes is large, and they are mainly used in construction, energy, transportation and other related fields. Therefore, for general occasions, the price of welded pipes is more affordable, while for some special fields, seamless steel pipes have become an indispensable and important material.

Conclusion: 

This article analyzes the price difference between seamless steel pipes and welded steel pipes from three aspects: production process, quality requirements, service life and market demand, hoping to provide some inspiration to readers. When purchasing steel pipes, you need to choose based on specific circumstances. Not only should you consider price factors, but also many aspects such as applicability, quality, and usage.

Go here to learn more about "How to Choose Seamless Pipe or Welded Pipe in Construction?"