Pressure class piping

[Salzilla]

Designing a pressure piping system to operate at maximum 16 psi.
Need to use 8" pipe, but sch. 40 is way too thick and heavy. Would like to use sch. 20s pipe.[1/4" wall].
only up to 16 psi steam [300F].
Any documentation that will permit use of sch. 20S pipe instead of 40? ie, any restrictions to use of sch. 20?
Rgds,

Sal

 

[owlscreech]

As far as B31.1 is concerned, there is no explicit restriction on the use of Sched 20 (I don't believe there is a 20S). The pipe wall must not only meet the minimum thickness requirements for pressure but also the thermal expansion, weight (dead, full of fluid), other sustained loads (i.e., valves & fittings), and occasional loads (e.g. seismic)that the pipe "sees" between supports/anchors. So 16 psig pressure load isn't much, but the other loads may be key players.