1. Appearance difference

2. Molding Process difference

3. Performance and Usage

In general, welded steel pipes can withhold 20 percent less working pressure than seamless ones. This reliability is the prime factor why people go for seamless steel pipe. As a matter of fact, all the industrial pipelines are done with seamless pipes only because the pipes undergo extreme thermal, chemical and mechanical workloads. Welded pipes are more preferred in aerospace, automobile and electronics industries where the budget is comparatively low, and so is the work pressure put on the pipes.

4. Available Sizes difference
For most of seamless steel pipe manufacturers in China, they produce original seamless pipe sizes maximum OD in 20 inch, 508 mm. Where usually is smaller than 16 inch, 406.4 mm, because of the equipment limits. And if client would like to purchase the seamless steel pipe more than above sizes, then hot expanding machining shall be used. But usually this kind hot expanded seamless steel pipe quality could not compare with the original seamless steel pipe.

On the contrary, welded steel pipe don't have these limitations, sizes available from 1-1/2 inch 48.3mm to 100 inch 2540 mm.

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