Seamless vs. Welded steel tubing

Seamless tubing is manufactured from a solid billet that has been extruded into a seamless pipe, known as a hollow or mother tube. That pipe is then reduced to smaller sizes using pilgering and/or cold drawing.

Welded tubing is manufactured using flat strip that is roll formed into a circular cross section and then longitudinally welded using TIG welding or Laser Welding processes. The welded tubing can also be drawn after welding, just like seamless tubing, which results in an even finer weld seam, tighter tolerances, and better surface finish.

Comparison

• PRICE: Welded tubing is typically much cheaper than seamless tubing. 
• LEAD TIME: For standard sizes, welded and seamless tubing have similar lead times and are often available in stock.
• THIN WALLS: Welded tubing is typically easier to produce in thinner wall sizes than seamless. 
• HEAVY WALLS: Heavy walls are generally more easily achieved with seamless tubing. 
• CUSTOM SIZES: For non-standard, custom sizes, seamless tubing is typically more economical and has a quicker delivery.
• CORROSION RESISTANCE: Seamless tubing is generally considered to be the most consistent material with the least impurities, which results in a higher corrosion resistance. Welded tubing can have impurities near the weld seam that causes it to be more susceptible to corrosion. 
• PRESSURE RATING: There is some debate over this as some would consider seamless and welded tubing to have the same pressure rating, while others argue that the welded tubing should be rated at 80% of the capacity of seamless. 

Conclusion

Despite what some would argue, there is not always a clear cut answer to which tube is always better. The application, the purchaser’s specifications, and the manufacturer’s capabilities should all be taken into account when making a decision.