we have cs, 10", preinsulated, underground piping. It is a hot water drainage pipe.
Is it required holiday testing before backfilling. For drainage piping is this holiday testing mandatory
It is a good practice to perform holiday testing before backfilling a preinsulated underground piping. If this test will be mandatory or not should be checked on your quality inspection plan, to see if it was requested or not.
You should be able to find that information in the Engineering specification used to order and install the pipe.
A good rule of thumb is, If the coating was specified, the testing is required.
It would seem a waste of money to pay for a coating that doesn't perform as specified. Or wasn't provided as requested.