A Pup? Thats is very interesting here in MExico we call them: “carretes”. I read all threads and nobody answered why its called PUP and not PoP (piece of pipe, i think I know why 
) . Now a spool is a shop welded system not a short piece of pipe, but Pup? Isnt that a small dog with big cute eyes and a wagling tail?
What Im doing is what B31.3 says:
M = the larger of 2.5(r2T )0.5 or tan (R1 − r2)
where:
r2 = mean radius of pipe using nominal wall T
T = miter pipe wall thickness (measured or minimum
per purchase specification)
Real problem is to convince old pipers (not that Im a “pup” but not that old either) and rule #3
NExt meeting with PEmex Im carring a gun (best convincing argument ever invented), BTW that might be a cool thread: “Worst ever client to deal with” Pemex is top of my list, they are government regulated and those burocrats have a lot of time on their hands to make my life a living hell.
Thanks for your input guys
Cheers!
Eliut