Cargo Tank Inspection and Product Change
You are at a bulk terminal in Philadelphia assigned to load a DOT 407 cargo tank with 4,800 gallons of UN1830 Sulfuric acid, 93%, Class 8, PG II. The cargo tank specification plate shows the last external visual inspection and leak test was 14 months ago, and the last internal visual inspection and pressure test was 4 years 10 months ago. The tank is placarded CORROSIVE and marked UN1789, Hydrochloric acid, from its previous load of 33% hydrochloric acid. The terminal wash rack is booked for 6 hours. The dispatcher says, “The tank passed its 5-year test, so just change the placard and load; acid is acid.” You also see the tank's bottom outlet valve is weeping a small amount of liquid.
1. Is the cargo tank legal to load as presented? Identify all deficiencies.
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No. The external visual inspection and leak test are required annually, and the record shows 14 months since the last one, so the tank is out of compliance on the annual inspection. The internal visual inspection and pressure test at 4 years 10 months are still within the 5-year interval, so that item alone would not bar loading. However, the bottom outlet valve is leaking, and a leaking cargo tank cannot be loaded until the valve is repaired and the tank is leak-tight. The tank is also still marked UN1789 for hydrochloric acid, but the new lading is UN1830 sulfuric acid. Changing only the placard is not enough; the UN number markings must be changed, and the tank must be cleaned and purged before the product change. The dispatcher’s statement that “acid is acid” is wrong because compatibility, cleaning, and marking all matter.
2. What must be done before loading the sulfuric acid?
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The leaking bottom outlet valve must be repaired and the tank leak-tested. The overdue annual external visual inspection and leak test must be completed by a qualified person. The tank must then be cleaned and purged to remove the hydrochloric acid residue, and the operator must verify that the tank lining, gaskets, and fittings are compatible with 93% sulfuric acid. The UN number marking must be changed from UN1789 to UN1830, and the CORROSIVE placard must be displayed correctly. The shipping paper and tank markings must match the new lading. Only after those steps should the tank be loaded. The six-hour wash-rack delay is an operational inconvenience, not a reason to load a dirty, leaking, or out-of-inspection tank.
3. If the pressure test date were 5 years 1 month ago instead of 4 years 10 months ago, how would your answer change?
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It would add another independent reason the tank cannot be loaded. A pressure test older than five years means the required periodic pressure test is overdue, so the tank must be removed from hazardous material service until the test is completed and passed. The annual external visual inspection and leak test would also still be overdue, and the leaking valve would still have to be repaired. In that situation the driver should refuse the load outright until the tank has current annual inspection, current pressure test, a repaired valve, and correct cleaning and markings. Loading would violate both the inspection interval and the leak-tightness requirement.