ERW vs EFW piping 2

[Rodddxl]

A client specified Sch 40, CS, ERW, ASTM A53-B, type E piping for a low pressure steam piping system we are going to fabricate. They provided the material requisition for what they are purchasing and the material description is EFW piping. I believe EFW piping is ASTM A671. Ignoring the fact they don't appear to be following their own specification, is there a reason they would go with EFW piping? A53-B is very common in this application and readily available. My concern is if the properties of EFW are significantly different than ERW. If it is stronger, is there something in the process conditions we are unaware of? If it is weaker, are they trying to cut corners?

 

[pennpiper]

Your comment = "My concern is if the properties of EFW are significantly different than ERW."

I don't think the ERW/EFW has anything to do with the properties of the metal plate for the pipe. ERW and EFW refers to the manner/method/type of welding (the plate). R=Resistance and F=Fusion thus you would have Electric Resistance Welded Pipe or Electric Fusion Welded Pipe. Both would be made from the same plate.

Sometimes its possible to do all the right things and still get bad results

 

[Rodddxl]

The weld method is specifically what I was curious about. I should have been more specific. I would assume both fusion and resistance welds would be comparable in strength.

 

[bimr]

Steam and condensate piping is often made schedule 80 just to have additional corrosion life (especially the condensate piping where the water chemistry is not well controlled). See ASME B31 Code for Pressure Piping, B31.1, Power Piping.

http://www.api.org/oil-and-natural-...natural-gas/ppts/other-files/decadefinal.ashx

"Some safety codes and regulatory agencies also assign a longitudinal joint factor to account for weld efficiency. The more common are 0.85 for ER W pipe and 0.60 for CW pipe. Seamless pipe enjoys a joint factor of 1.00. This means that some designers consider ER W pipe as 85 percent as efficient as seamless pipe and CW pipe only 60 percent as efficient for the same application. Therefore, for a given application, ER W pipe would require a heavier wall than seamless pipe, and CW pipe, in turn, would require a heavier wall than ER W pipe."

http://usstubular.com/resources/lib...eel-tubular-products-standard-and-line-pipe/.

Here is a specification for steel pipe:

http://www.indps.com/pdfs/Specification_for_Steel_Pipe.pdf

There is a never-ending debate whether seamless is better than welded. The arguments typically center on structural integrity and corrosion resistance of the weld, severity of the intended service, NDT and inspection requirements and delivery time. In reality, both production methods can provide the necessary quality and service life, corrosion resistance and reliability. Generally welded tubes are less expensive, have narrower tolerances, thinner nominal wall thickness, better concentricity (outer/inner diameter OD/ID), higher internal surface quality and are often chosen since they can be produced in longer lengths with larger diameters. Seamless tubes are needed where heavy wall thickness is combined with small diameters making forming of plate or strip complicated and where the standard specifically specifies seamless.

 

[LittleInch]

I don't believe there is any significant difference between the two. You needed to look at you're design code to see what joint factor applies.

What creates the heat for the fusion varies, some are laser, some electrodes. Three seems to be no consistent description of efw.

See these previous posts

http://www.eng-tips.com/viewthread.cfm?qid=105810

http://www.eng-tips.com/viewthread.cfm?qid=153703

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KevinNZ]

The type of pipe seam weld only effects the "E" value used for hoop stress calculation and therefore the min pipe thickness.