Seamless vs precision welded tube: when to choose each

Seamless tube in high-demand applications

In sectors such as oil and gas, power generation or heavy boiler-making, the seamless steel tube is the reference. Made from a pierced solid bar, it has no longitudinal seam and withstands very high pressures and thick walls with homogeneous behaviour. For large diameters and extreme conditions, it is the logical choice.

The nuance: "seamless" doesn't always mean better

The idea that seamless tube is superior in every case comes from large-diameter applications. In small precision diameters that advantage disappears: modern induction welding, followed by calibration and cold drawing, produces a tube with homogeneous strength, tighter tolerances and a better inner finish than many seamless tubes of the same size, and at a lower cost.

Precision welded tube for fluid lines and small diameters

When the application works in the 3 to 25 mm range —fluid lines, small-diameter hydraulic components, axles, rollers or structures— precision welded tube offers decisive advantages: an exact diameter to the tenth of a millimetre, a reduced inner bead (≤ 0.15 mm) or removed, and a smooth mirror-like bore for optimal flow and sealing. All with the option of a surface ready for direct chrome or zinc plating.

How to choose for your application

The practical rule is simple: if you need large diameters, very thick walls or extreme pressures, seamless is your option. If you work with small diameters demanding tolerance, finish and tight cost, precision welded performs just as well or better. When in doubt, the deciding criterion is the combination of diameter, tolerance and working pressure.

Supply and Delmàs welded precision

Delmàs manufactures precision welded and calibrated steel tube since 1956, specialising in small diameters from 3 to 25 mm. Explore our PREMIUM, OPTIM and PRECISE ranges or talk to our technical team to find the optimal solution.

Frequently asked questions

Can a welded tube replace a seamless one?

In small diameters and moderate pressures, yes: precision welded tube offers equivalent performance with better tolerance and finish. For large diameters or extreme pressures, seamless remains the reference.

What inner finish does precision welded tube offer?

From a controlled inner bead (≤ 0.15 mm) to its complete removal, with smooth mirror-like bores ideal for fluid lines and hydraulic applications.

Do you work with custom sizes and cuts?

Yes. We manufacture exact diameters to the tenth of a millimetre and supply in bars, coils or cut to the size your project requires.