ASME B31.3 Impact test requirement

[Corgas]

Reviewing some PI & D for a new project came across a piping spool. Piping spec calls for :
Mat: A-106 Gr B.
Design Condi:-20°F - 750°F
No mention of impact test requirements, even though, it mentions "according to ASME B31.3".

This particular piping spec allows following :

Pipe Size Schedule
4” Sch. 160 or greater
6” Sch. 120 or greater
8” Sch. 100 or greater
10” Sch. 80 or greater
12” thru 16” Sch. 60 or greater
18” and up Sch. 40 or greater
As you can see, everything above 6" (sch 120) is thicker than 0.5", so according to ASME B31.3 (2008) they need to be impact tested.

Can anyone confirm my appreciation?

How can I take temp reduction(s) due to stress?

Thanks,

Corgas

 

[stanweld]

Why do you need the -20 MDMT?

 

[Corgas]

stanweld :

MDMT has been speced out in piping spec as -20 °F.Whoever wrote piping spec selected those ranges.

Design was done by local consulting eng firm and they adopted this spec.

Point is, thickest pipe we have found it is only good to +9 °F (according to ASME B31.3)