Tank Trailer Testing 101: DOT, EPA Method 27, and Staying Compliant

Why Tank Trailers Face Extra Scrutiny

Cargo tank trailers carry some of the highest regulatory burden of any equipment on the road, and for good reason — a failure in transit can mean a spill, a hazmat incident, or worse. That's why DOT and EPA both require periodic testing on top of the standard annual inspection.

What Gets Tested

• DOT pressure test — verifies the tank and its fittings hold required pressure without leaking.
• DOT thickness test — measures shell and head thickness to catch corrosion or wear before it becomes a structural issue.
• EPA Method 27 — a vapor-tightness test required for tankers hauling volatile organic compounds, confirming vapor recovery systems aren't leaking.

Test intervals depend on the commodity hauled and the tank specification, ranging from annually to every five years, so it's worth confirming your schedule rather than assuming.

What Happens If You Miss a Test Window

A tanker that's out of test can't legally haul product, full stop. That means a trailer sitting idle instead of generating revenue, and depending on your customer contracts, potential compliance issues on their end too.

We track test due dates for the tankers we service and can schedule testing before you're caught off guard. If you're not sure when your fleet's tanks were last certified, send us your unit numbers and we'll help you sort out the schedule.