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When is ERW pipe acceptable instead of seamless?
Short answer
ERW pipe is acceptable for most carbon steel water, gas, air, structural and line-pipe duties, where its lower cost and tighter wall tolerance are real advantages. Seamless pipe is preferred for high-temperature process piping such as A106, sour and cyclic service, and wherever the specification or code requires it.
ERW vs Seamless Pipe at a glance
| ERW | Seamless Pipe | |
|---|---|---|
| Process | HF resistance welding | Piercing and rolling |
| Materials | Mostly carbon steel | Carbon, alloy, stainless, nickel |
| Typical specs | API 5L ERW/HFW, A53 Type E, IS 1239, IS 3589 | A106, A335, A312 SMLS |
| Wall thickness range | Thin to medium | Thin to very heavy |
| Cost | Lower | Higher |
Which should you choose?
There's no universal "winner": the right choice depends on service conditions, codes and cost. Share your conditions with us for a recommendation.
How ERW is made
Strip is formed into a tube and its edges are heated by high-frequency current and forged together without filler. The weld zone is then normalised or heat treated and tested ultrasonically.
Indian standards
In India, IS 1239 and IS 3589 ERW pipes are widely used for water and utility lines, while process piping usually stays seamless. See carbon steel.
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Frequently asked questions
Is ERW pipe suitable for oil and gas pipelines?
Yes, API 5L ERW pipe is widely used in pipelines, including PSL 2, with weld-seam testing.
Can stainless pipe be ERW?
Stainless welded pipe is usually made by TIG or laser welding to A312 WLD or A358, rather than carbon-steel ERW.
What is the main difference between ERW and Seamless Pipe?
ERW pipe is formed from strip and high-frequency welded without filler. It's economical for carbon steel water, gas, structural and line pipe. Seamless pipe is preferred for high-temperature process piping (A106) and demanding pressure service.
When should I choose ERW?
Pipelines, water, structural and utility lines.
When should I choose Seamless?
High-temperature process and critical pressure service.