"Skip Gundlach" writes:

I went to check it out and found that the conduit is
actually Schedule 40 grey pipe.

As far as the pipe size is concerned, correct.

Fittings are a different matter.

So, my question is, would this work for the Schedule 40 pipe installations
in sanitary service,

Negative.

Sch 40 pipe (white PVC), ABS (Black) and sch 80 pipe (gray PVC), are rated
for sanitation service, but who in their right mind would put it on a boat?

White PVC has no UV inhibitors and if left in the sun, will probably
fracture in less than 1 year in a place like SoCal or Fla.

Conduit and Sch 80 pipe both have UV inhibitors.

HTH

Lew