What is necessary for the underground duct system before it is coated or placed in the ground?

Prior to coating or burying an underground duct system, testing is essential to ensure that the system is free from leaks and is functioning properly. This step is crucial because it confirms the integrity of the ducts under operational pressures and verifies that any systems installed meet safety and performance standards. Testing can involve various methods, including pressure testing, to identify any deficiencies that need to be addressed before the system is concealed.

Painting, inspecting, and cleaning, while they may all have their own importance in maintenance and installation practices, do not serve the same critical function as testing. Painting may provide corrosion resistance, inspection is typically done at various stages but is not specifically mandated before burial, and cleaning aids in the operation but is not a prerequisite condition for installation. Thus, testing directly contributes to the reliability and safety of the duct system once it is underground.