The length of pupsâ€™ rule of thumb was 1.5dia or min 6" (152 frog dimensions) the length is based on fabrication .Anything less then 6" of 4" pipe is hard to do field end preps and field welds.
Did you skip the piping course?
I agree with ollie on the 6" / 1 1/2 D rule for pups ...
Having said that, I've seen make-up spools that were pretty short. 2" / 50 mm pipe between weld necks.
I'm no welding expert, but I think the trick used was to make the first weld to a longer piece of pipe, then cut the pipe to length, then weld the second flange on. That way you get a "normal" heat pattern in both welds as there's more material to carry the heat away.
One other question though, can anyone tell me where the name PUP piece originated from?
Is it an abbreviation, an achronynm or a made up word??
I asked the question because
13 years 1 month ago #3720
I asked the question because I have always believed it to be 50mm. ie. the min the shop could fabricate. I am being told otherwise and i disagree. i just wanted other views on it to make my case. There are no field welds on the job so thats not an issue.
Minimum spacing between circumferential welds
13 years 1 month ago #3721
Minimum spacing between circumferential welds joints shall be 2" or 6 times the wall thickness of the pipe, whichever is greater