A106 and A53 the most commonly used carbon steel pipe types in industry today, and they’re very similar. But while the differences between A106 and A53 are few, they matter a great deal in terms of when and where each is specified.

To ensure you purchase the correct pipe, two things are a must: A basic understanding of seamless and welded seam pipe, and providing detailed specs. If you read the ASTM and ASME standards for A106 and A53 pipe, you’d quickly observe how similar they are in terms of chemical makeup and manufacture. The most important difference is that pipe meeting the A106 standard must be seamless while pipe meeting A53 can either be seamless or welded.

Welded seam pipe is made by curling a steel plate into a cylinder and then joining the edges via a weld. Seamless pipe is made by piercing cylindrical bars of steel through the middle while it’s hot, creating the same shape but without a seam.

The reason for the difference lies in the suitable applications for each type. A53 pipe is best suited for transport of air, water, steam and oil in low- and medium pressure applications across the industrial spectrum. It’s also commonly used as structural steel.

A106 pipe is formulated specifically for high-temperature and high-pressure service, usually in power generation applications. High-pressure, high-heat service environments put added stress on pipe, so seamless pipe types are preferred in those settings since they’re at less risk of failure under stress than their welded counterparts.