Inspection, Testing and Maintenance
Inspection stages
Mechanical inspection is staged: rough-in before concealment, final after completion. At rough-in, verify support, clearances, duct sealing, vent slope, combustion-air openings, and access. At final, verify appliance listing, labeling, controls, clearances, termination, and operational tests. Concealed work that was not inspected may need to be exposed; the permit holder bears that cost.
Tests the inspector witnesses or verifies
- Gas piping: pressure test with air or inert gas, gauge visible, no drop during the specified period; joints must be accessible or tested before concealment.
- Duct systems: leakage testing where required by the code or the design; sealant and closure systems must be listed for the application.
- Refrigeration: evacuation and leak testing per the installation instructions and code; refrigerant charge and ventilation for machinery rooms.
- Fire and smoke dampers: access, correct installation, and operational verification where required.
Worked example
A contractor pressure-tests new gas piping at 10 psi and leaves the gauge at 9.5 psi after 15 minutes. The contractor says the drop is temperature effect. Reasoning: a falling gauge indicates a leak or an unsealed test boundary until proven otherwise. The inspector should not accept the test. The proper response is to locate and repair the leak, then repeat the full test with the gauge in view. Temperature correction is not a substitute for a tight system.
Maintenance and records
The code requires mechanical systems to be maintained in safe working condition. Maintenance records matter for commercial cooking ventilation, boilers, and refrigeration machinery rooms. The inspector final approval is not a warranty; it confirms code compliance at the time of inspection.
Traps
Accepting a test with the gauge out of sight. Confusing a working-pressure test with a leak-detection test. Signing off final without operational verification. Missing that a concealed joint was never tested.