Google is a wonderful thing, but the market seems to be garden hoses and fire hoses. The biggest I found was 2-1/2 inch. The highest pressure was 300 psig.
If you were to find one big enough and strong enough for your application, I don't see how you would keep a pig from starting down the wrong leg and then tumbling (which tends to fold a foam pig so the sweep effeciency goes way down).
This just sounds like a bad idea.
David