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
"Holiday testing" (or spark testing) is typically required by the owner as part of a contract requirement. Hoilday testing is only necessary to verify the integrity of a protective coating. No coating, no holiday testing required..
Could this "hot water drainage" pipe be part of a condensate return system running back to a boiler plant ?
You ask "For drainage piping is this holiday testing mandatory"
If it is a coated pipe and testing is required by the contract, then yes...