All:

My question is: a 1" sheet steel has rolled up to form a 50" OD pipe, after rolling, both of the edges of the sheet are straight at some extent, the welder claped the edge together, then weld it, since the pipe is not exactly round, after he done the welds, he placed the weld pipe in another roller and make it round.

I am concerned that rolling the second time would introduce stress at the welds and affect the service life, but I could not fine any information in API 5L to determine how serious it can affect the service life and should I accept that pipe.
any help on this issue is appriciated.

Tracey

Think about it:  putting a weld in the pipe has already introduced residual stress.  Cold expansion is considered beneficial in reducing the residual stress.  Cold sizing may also be beneficial provided that it is within the limits of subclause 8.9.  If the purchase specification has not prohibited cold sizing, and it is within the stipulated limits, you have no option but to accept the pipe.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04
 

Quite common to reroll after seaming.  Your other alternative is to accept egg-shaped and heart-shaped pipe spools.