ISO for ASTM and Viceversa

[nickypaliwal]

Can we use ISO spec material for piping and ASTM spec material for pipeline ?

Also advise if we can use a flange with higher class rating in a piping with lower class rating ?
If yes, Where and If no, why not ?

 

[metengr]

What is the code of construction or client design specification allow?

 

[nickypaliwal]

In general, Can we use a higher class fitting in a lower class piping or pipeline?

Also can we use piping or pipenline fittings/flanges in place or each other ?