HI LO on welding of pipelines

Date 02-10-2018 10:54

Hello,

If HI-LO is almost impossible to remove during fit up of pipes, where is the best location to put the internal misalignment, is ti bottom or on top of the pipe? Considering there is a requirement of internal coating.

Thanks

By Steelslinger (**)

Date 02-12-2018 12:50

What do the contract specs state? What code? What type of service is the pipe?

By jarsanb (***)

Date 02-12-2018 18:29

https://primis.phmsa.dot.gov/rd/mtgs/071812/kenlee.pdf
http://napca.com/webfiles/NAPCA%202010%20Workshop-Kenneth%20Lee%20Presentation.pdf

Also see:
API 1104 7.2
ASME B31.8 fig. I-5

By TimGary (****)

Date 02-12-2018 20:01

Great question!

First response would but what has already been asked, code, spec, service, etc.
If these docs don't have what you would need, I would, whenever possible, not be so worried about top or bottom, but arranging the fit so that the hi-lo step steps down with the direction of product flow. This would help minimize, but not eliminate the flow turbulence that eats away the pipe wall from the inside.

Tim