Regulatory Inspection Requirements Under 49 CFR Part 180
Cargo tank motor vehicles (CTMVs) are subject to a comprehensive inspection and testing program under 49 CFR Part 180 that goes far beyond the standard CMV annual inspection. The Part 180 program requires a combination of visual inspections, pressure tests, and lining inspections at intervals specified by tank specification type and the nature of the commodity transported. Most cargo tanks must receive an annual requalification inspection conducted by a registered inspector using PHMSA-approved procedures.
The annual inspection includes a visual examination of the entire external surface for dents, gouges, corrosion, weld defects, and any damage that could compromise structural integrity. The inspector checks all pressure/vacuum relief valves by manually lifting the valve stem to verify the spring is not corroded and the valve seats properly. Thermometer wells, gauging devices, and manhole covers are inspected for condition and leak-free closure. The inspector also verifies that the specification plate — stamped with the tank type, test pressure, capacity, and last inspection date — is securely attached and legible.
Pressure testing (also called leak testing) is required at intervals specified for each tank type. An MC-306 petroleum tanker typically requires pressure testing every five years. During this test, the tank is pressurized with air or inert gas to its maximum allowable working pressure (MAWP) and held for a set period while an inspector checks every weld, seam, fitting, and valve connection for leaks using soap solution or electronic leak detection equipment. Any leaking component must be repaired and the test repeated before the tank is returned to service.
Before each trip, the driver is responsible for a pre-trip visual inspection of the cargo tank, which is a subset of the regulatory inspection. The driver checks that dome covers are properly latched and sealed, that discharge valves are closed, that vapor vent covers are secure, and that there are no visible signs of leaks (staining, residue, odors) on the tank exterior. This inspection is required by both 49 CFR Part 392 and Part 180 and must be documented in the driver's pre-trip inspection record.