Seamless V Welded in relation to Pipe Diameter

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11 years 6 months ago - 11 years 6 months ago #8234 by Billy
Most S/S specs specify seamless pipe at small diameters and welded at larger diameters. Can anyone answer why this is so?

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11 years 6 months ago - 11 years 6 months ago #6648 by 11echo
Bottom line reason is fabrication cost. Seamless pipe is extruded, and the cost goes up exponentially as the size is increased. However weld pipe, in larger sizes, now becomes easier because it’s easier to get internal welding machine through the bore of the pipe.

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11 years 5 months ago - 11 years 5 months ago #6650 by Billy
That's all fine (and make sense) BUT....seamweld IS available in the smaller sizes AND is cheaper........so why specify seamless in the small bores if that's the only explanation?

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11 years 5 months ago - 11 years 5 months ago #6652 by Anton
As seamless pipe has no longitudinal welding it's considered a better option of pressure piping - no welds to fail and split under pressure.

Seam weld pipe manufacturers, however, will tell you that if a seam weld pipe is manufactured properly, it is as good as seamless - and cheaper.

- If you're the smartest person in the room ... you're in the wrong room.

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11 years 5 months ago - 11 years 5 months ago #6654 by 11echo
I’ve used ERW pipe a number of times, limited by company spec.s. To be honest I believe the real answer you are looking for is it’s because of the personnel prejudice of the engineer! My dealing with older engineers they “hate” butterfly valves, early ones were very poor design/quality and their use caused a lot of problems. So engineers of that time think all butterfly valves are problems waiting to happen and avoid there use even today. Same thing on welded seam pipe, I remember in one of my first classes the instructor said of spiral welded pipe, it’s not as strong and limited to atmospheric gravity type drains. Thirty years later and I’m seeing its use on D.O.T. pipeline! But you can’t blame the engineers totally, put yourself in their shoes …your engineering a crude oil system on a platform in the Gulf of Mexico, where a catastrophic failure would be a major “deal changer”, especially in today’s political climate …so you going to spec out a cheaper ERW pipe or go with SMLS?

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10 years 6 months ago - 10 years 6 months ago #6916 by katewinslet
Replied by katewinslet on topic Re: Seamless V Welded in relation to Pipe Diameter
Just curious, how did you resolve the problem?

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