PUP Piece how long???

I have 2 Elbows and a pup piece inbetween. Whats the minimun length that it can be what governs it. In this case its 12" Sch20 C.S.
Evertone i asked seems to have a different answer.

The length of pups’ 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??

WWIU

Ollie,

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 joints shall be 2" or 6 times the wall thickness of the pipe, whichever is greater

Going back to whichwayisup's question. What does PUP stand for? If it is for a Make-Up Piece, why isnt it called a MUP?