Pup Spool maximum length
Pup Spool maximum length
(OP)
Hi,
I am trying to find out if there is a regulation in regards to the maximum length of a pup spool. I have tried looking through ASME B31.3 and found nothing. Is there an "official" name for a pup?
Thank you.
I am trying to find out if there is a regulation in regards to the maximum length of a pup spool. I have tried looking through ASME B31.3 and found nothing. Is there an "official" name for a pup?
Thank you.





RE: Pup Spool maximum length
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pup Spool maximum length
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http://www.eng-tips.com/viewthread.cfm?qid=242240
http://www.eng-tips.com/viewthread.cfm?qid=238880
There is lots more if you use "Search" at the top of the screen.
prognosis: Lead or Lag
RE: Pup Spool maximum length
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pup Spool maximum length
You appear to be taking a very rigid position on the minimum distance between two Circumferential (Butt) Welds.
One diameter may be what you or your Company prefers to use but there is nothing in the ASME Code or API Standard to support that.
The 1D Rule starts to lose it's validity when you get much over 2"(DN50). It really gets ridiculous when you get to 24"(DN600) or above.
Some people (me included) prefer to use something that is more logical and practical. This is based on the wall thickness of the material (pipe) and has nothing to do with the Diameter of the pipe.
Most of the time I set 5t (five times the wall thickness of the pipe) as the working minimum distance between welds. With approval I have sometimes allowed 3t as a bare minimum. The 3t situation may result in an overlap of the Heat affected Zone and require PWHT. If the Piping is going to require PWHT anyway then there is no added charge.
prognosis: Lead or Lag
RE: Pup Spool maximum length
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pup Spool maximum length
With regards to minimum length, as mentioned above any general rules of thumb will only apply over a certain range of ODs. Another rule of thumb I have heard is 2xWT toe-to-toe. The main requirement is to ensure that there is no interaction between the HAZ's.