[whichwayisup]

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