6.1 Inspecting Tank Vehicles: Leaks, Valves, Covers, Vents & Emergency Equipment
Key Takeaways
- The AAMVA manual says the most important item to check on all tank vehicles is leaks.
- Carrying liquids or gases in a leaking tank is a crime: you will be cited, stopped from driving further, and may be liable for cleanup.
- Check the shell for dents or leaks; intake, discharge, and cut-off valves; pipes, connections, and hoses; and manhole covers with gaskets and clear vents.
- Never drive a tank vehicle with open valves or manhole covers.
- A power unit hauling placarded hazmat needs a fire extinguisher rated 10 B:C or more, plus three reflective triangles or permitted alternatives.
The AAMVA manual opens the tank vehicle section with inspection: before loading, unloading, or driving a tanker, inspect the vehicle, so it is safe to carry the liquid or gas and safe to drive. Tank vehicles come in many types and sizes, so the manual also says to check the vehicle's operator manual to learn how to inspect your specific tank.
The Manual's Tank Checklist (8.1)
Leaks: the most important item
On all tank vehicles, the most important item to check for is leaks. Check under and around the vehicle for signs of any leaking. Don't carry liquids or gases in a leaking tank. To do so is a crime. You will be cited and prevented from driving further. You may also be liable for the clean-up of any spill.
In general, check:
| Item | What to look for |
|---|---|
| Tank body or shell | Dents or leaks |
| Intake, discharge, and cut-off valves | Valves in the correct position before loading, unloading, or moving |
| Pipes, connections, and hoses | Leaks, especially around joints |
| Manhole covers and vents | Covers have gaskets and close correctly; vents are clear so they work correctly |
Special purpose equipment (8.1.2)
If the vehicle has any of these, make sure it works:
- Vapor recovery kits
- Grounding and bonding cables
- Emergency shut-off systems
- Built-in fire extinguisher
Never drive a tank vehicle with open valves or manhole covers.
Emergency equipment (8.1.3)
Check the emergency equipment required for your vehicle. Find out what you are required to carry, and make sure you have it and it works.
Where Tank Checks Fit the Seven-Step Inspection
The general inspection method in the manual has seven steps. Tank items belong in several of them:
| Step | Name | Tank-specific additions |
|---|---|---|
| 1 | Vehicle overview | Look under and around for fresh product leaks and puddles; review the last inspection report |
| 2 | Check engine compartment | Standard checks |
| 3 | Start engine and inspect inside the cab | Emergency equipment present; in-cab controls for air-operated valves if equipped |
| 4 | Turn off engine and check lights | Standard checks |
| 5 | Do walkaround inspection | Shell, valves, piping, hoses, outlets and caps, manholes and vents (where accessible), remote shut-off, bonding cable, test markings |
| 6 | Check signal lights | Standard checks |
| 7 | Start the engine and check (brakes) | Standard checks |
Federal rules also require the driver to be satisfied that the vehicle is in good operating condition and that required emergency equipment is in place before driving (49 CFR 392.7 and 396.13).
Detailed Hardware Checks
Shell and structure
- Dents, cuts, gouges, and corrosion, especially at welds and where the tank attaches to the frame or running gear. Registered inspectors judge dents against limits in 49 CFR 180.411: for dents at welds, the maximum allowed depth is 1/2 inch, and any tank showing damage that might make it unsafe must be tested and inspected before further use (180.407(b)).
- Wet spots, stains, or residue trailing from seams, fittings, or insulation jackets. Insulated tanks hide the inner shell, so look for product at jacket seams and drain points.
Manhole covers
- The gasket is present, seated, and not cut, cracked, hardened, or swollen.
- The cover closes correctly and all fasteners are tight. Federal design rules require fastenings that keep covers from opening due to vibration or a rollover.
- The safety device works. Each manhole, fill, and washout cover must have a device that prevents the cover from opening fully when internal pressure is present (49 CFR 178.345-5). Never wire it open or bypass it.
- Work on top of a tank only where you can do it safely, using the ladder, walkway, and fall protection provided.
Vents and relief devices
- Vents are clear, with no product buildup, debris, ice, or covers left on them.
- Pressure and vacuum relief devices are not damaged, painted over, or blocked. A blocked vacuum vent can let the tank collapse during unloading (Section 3.3).
Valves, piping, and outlets
- Internal valves closed and the operating linkage or air controls in good condition.
- External valves closed with handles secure.
- Caps or plugs on every outlet, with gaskets, fastened tight. Piping beyond a stop valve must end in another valve or leak-tight closure.
- Shear sections not bent, cracked, welded over, or reinforced.
- No drips from valve stems, packing, or couplings.
Emergency shut-off system
- Locate each remote closure control and confirm it is not damaged or obstructed.
- Where your carrier's procedure calls for it, operate the control and confirm the valves close.
- Make sure the thermal closure elements (fusible links or similar) are present and not painted over or bypassed.
Bonding and grounding
- Cable present, not frayed, with a clean clamp and a good connection point.
Test and inspection markings
- Retest markings are legible and not past due for the tank's service (Section 6.2). External visual inspections include checking that all required markings are legible.
Emergency Equipment Rules (49 CFR 393.95)
| Equipment | Requirement |
|---|---|
| Fire extinguisher, power unit hauling placarded hazardous materials | UL rating of 10 B:C or more |
| Fire extinguisher, power unit not hauling hazmat | 5 B:C or more, or two extinguishers of 4 B:C each |
| Extinguisher condition | Securely mounted, readily accessible, filled, with a way to see that it is charged |
| Warning devices | Three bidirectional emergency reflective triangles, or at least six fusees |
For cargo tanks used for flammable liquids or flammable gases, loaded or empty, flame-producing warning devices may not be used (49 CFR 392.25), so carry the triangles.
Inspecting During the Trip and After
The general inspection rules still apply. During a trip, watch gauges, use your senses, and check critical items when you stop. For a tank, also look again for leaks at every stop, especially after loading, unloading, or a hard bump. Report defects on your post-trip inspection report so the carrier can repair them.
Common Test Traps
- "What is the most important item to check on a tank vehicle?" Leaks.
- "Can you drive with a small leak to the next stop?" No. Carrying liquids in a leaking tank is a crime.
- "Is it OK to drive with a manhole cover open on an empty tank?" No. Never drive with open valves or manhole covers.
- "What special purpose equipment should you check?" Vapor recovery kits, grounding and bonding cables, emergency shut-off systems, and built-in fire extinguishers.
According to the AAMVA manual, what is the most important item to check for on all tank vehicles?
Which of these does the AAMVA manual list as special purpose equipment to check on a tank vehicle, if equipped?
A power unit is hauling a placarded load of a flammable liquid in a cargo tank. What fire extinguisher does 49 CFR 393.95 require?