Building on decades of experience in supplying pipe system solutions for oil, gas, energy, power, desalination, process plants, civil works, and other projects worldwide, Gerab has earned the trust of the world’s leading NOCs, IOCs, EPCs, and PMCs for their pipe system needs. We are recognized as a dependable welded and seamless pipe supplier, including fittings, and accessories. So what is the difference between seamless and welded pipes, and why should it matter which to choose, as long as they both conform to the highest international quality standards?

 Both seamless and welded pipes have advantages and disadvantages that tip the scales toward choosing one or the other. Let’s start with a brief explanation of each.

Welded and Seamless Steel Pipes Guide

Seamless Pipes

As the names imply, seamless pipes are pipes that are uniform in construction and do not have the welding seam or crease of welded pipes. Seamless pipes are constructed from a single cylindrical solid piece of steel called a billet. Different processes can be used to fabricate the billet into a seamless pipe. Most commonly, the billet is heated and stretched through an extrusion process while being pierced through the center with a mandrel. This is followed by rolling and stretching the pipe until it meets the desired length, diameter, and thickness requirements. The result is a uniform pipe that is homogeneous across its length.

Welded vs Seamless Steel Pipes Guide

Welded Pipes

Welded pipes, on the other hand, are made by cold-forming flat strips, sheets, or plates (called skelps) into a round shape by a roller or plate-bending machine. The pipe is then welded through a process called submerged arc welding (SAW), which leaves behind a weld bead that must then be polished to complete the seal. Alternatively, a high-frequency electrical current is passed between the edges, causing them to melt and fuse. This is called electric resistance welding (ERW). Generally, welded pipes are considered inherently weaker due to the weld seam, and require additional testing to ensure the integrity of the seam. However, they are easier to manufacture and thus are cheaper and more readily relied on for a wider range of applications.

The difference in the manufacturing process between seamless and welded pipes results in different properties between one type over the other. These can be summarized as follows:

Strength

As they do not have the welding seam and potential variation in material because of the type of filler material used, seamless pipes are considered stronger and are relied on by applications that require higher pressures and loads. However, with proper welding techniques and quality control, welded pipes can still be highly durable and suitable for many applications.

Length

Due to the more complex nature of manufacture, seamless pipes come in a shorter range of length than welded pipes. The latter can be fabricated into longer continuous fixed lengths.

Diameter

Seamless pipes can reach diameters of up to 24 inches (sometimes even more!), whereas welded pipes can be manufactured to the diameter needed.

Corrosion Resistance

Due to their uniform structure, seamless pipes are considered more corrosion-resistant. This uniformity contributes to their improved resistance against corrosion, as there are no vulnerable points like welds that can be susceptible to corrosion initiation or stress corrosion cracking.

When selecting welded pipes for corrosion-resistant applications, it’s essential to choose appropriate materials such as corrosion-resistant alloys or coatings. By selecting the right materials, weld joint integrity can be maintained, and the overall corrosion resistance of the pipe can be enhanced.

Fluid Dynamics

In the extrusion process, seamless pipes tend to have a smoother surface quality than welded pipes. The smoother interior of seamless pipes minimizes turbulence and friction, allowing for more efficient fluid flow. However, the impact of weld seams on fluid dynamics can vary depending on the welding technique and quality of the weld.

Cost

The production process in manufacturing seamless pipes is more complex than welded pipes. This makes seamless pipes more expensive and less readily available than welded pipes.

The welding process is generally less time-consuming and requires fewer equipment and resources, making it more cost-effective. The manufacturing process of welded pipes allows for efficient mass production, reducing production costs per unit. Seamless pipes, on the other hand, may have limitations in terms of production volume due to the complexity of the manufacturing process.

Conclusion

Despite being more expensive to produce, seamless pipes are generally preferred in applications where high temperatures and pressures or more corrosive environments are present. Welded pipes tend to be chosen in lower temperature and pressure applications, or where more versatility is needed to accommodate length and size variations.

It is worth noting that both seamless and welded pipes have been relied on for a very long time, and international quality and manufacturing standards have contributed to narrowing the advantage gaps between them. Seamless pipes tend to be relied on more in oil & gas and energy applications, while welded pipes are the preferred option across most municipal, civil, and industrial applications where service variables allow for lower pressures and temperature tolerances.

All pipes must conform to client-selected specifications and international standards. Pipe system solutions, however, are constructed and operate in dynamic environments. They need to be sourced from reliable steel pipe suppliers, tested according to stringent methods, and stored and handled appropriately. They need to be readily available to meet stringent construction workflow schedules and be supported by availability, logistics considerations, maintenance and repair capabilities, as well as complementary fittings and accessories.

A pipe system supplier can play an instrumental role in helping clients to choose the appropriate type of pipe, helping to reduce costs, improve reliability, and contribute to the overall success of a pipe system solution across its lifespan. 

It is critical that you consult with a subject matter expert to select the correct pipes for your projects. At Gerab, we have a dedicated team of technical experts who work closely with the customers and suppliers to ensure the technical specification requirements are understood and complied with. Our team scrutinizes customer specification requirements, conducts technical negotiations with customers, and makes technical agreements. At times they assist customers in optimizing the material selection. It also adds confidence to the customer in meeting the quality and compliance with the specification. Our team identifies the requirement with the suppliers and acts as a customer representative to ensure the supplier understands and fulfills the requirements.