DOT compliance
Tank testing that holds up at terminal and DOT.
Annual external visual, periodic internal inspection, pressure testing, and lining inspection performed per 49 CFR 180.407. Documentation that survives the audit.
Tank trailers transporting petroleum products are required to pass a series of inspections and tests on a schedule defined by 49 CFR 180.407. Miss a test, and the unit is out of service. Pass with sloppy documentation, and the next terminal audit becomes a problem. Post Onsite performs the full slate of required tank testing — visual inspection, internal inspection, pressure testing, lining inspection — on a schedule that keeps your tanks compliant and your terminals happy.
Tank testing we perform
Annual external visual inspection (V)
Required annually per 49 CFR 180.407(d). External condition of the tank, piping, valves, fittings, manhole assemblies, vapor recovery. Documented with photos.
Internal inspection (I)
Required at 1-year and 5-year intervals depending on tank type and contents. Internal condition of shell, baffles, manhole, valve mounting plates. Documented per code.
Pressure test (P) — 5-year
Hydrostatic or pneumatic pressure test per 49 CFR 180.407(g). Required at 5-year intervals for most petroleum tanks. Performed in our test bay with calibrated equipment.
Lining inspection (L)
Required for lined tanks, typically annually. Visual and spark test of interior lining. Documentation of lining condition. Re-lining performed when needed.
Thickness testing (T)
Ultrasonic thickness testing of tank shell when external or internal inspection raises concerns. Spot or full-grid mapping. Documentation of measurements.
Vapor recovery testing
Required for tanks loading vapor-controlled products at terminals. Pressure and vacuum testing of vapor recovery system. Certification provided.
Schedule the work or request an assessment.
Mon–Fri 7am–6pm. Emergency response 24/7.
What good looks like
When you bring a tank to Post Onsite, here's what you should expect.
- Reminder calls before your test due dates
- Same-week appointment availability for fleet customers
- Full inspection performed against the specific 49 CFR requirements
- Defects identified with photos and quoted for repair
- Required corrections performed during the same visit when possible
- Documentation completed and provided before unit leaves
- Records compatible with terminal compliance audits
Why operators trust Post Onsite for testing
Tank testing isn't a checkbox exercise. We've seen what happens when sloppy testing finds nothing wrong, the tank goes back to work, and a real defect causes a real incident six months later. Our testing process is built to actually find what's there.
We also understand the documentation reality. Terminal compliance auditors and DOT inspectors don't care about your verbal explanation. They want paperwork. Our testing documentation is complete, clear, and structured for the audits our customers face.
Common questions
How do I know which tests my trailer is due for?
Bring us the trailer or send us the unit number and previous documentation. We'll review the inspection history and tell you exactly what's due, what's coming up, and when. Fleet customers get reminder calls before due dates so nothing slips.
What if my tank fails a test?
We document the failure, walk you through what's needed to bring it back into compliance, and quote the corrections. Most failures involve corrosion, weld defects, or lining issues — all things we're equipped to repair. We complete the corrections, retest, and get the unit back on the road.
How long does a full tank test take?
Annual external visual: 1-2 hours. Internal inspection: half-day to full day depending on tank size. Pressure test: full day including setup, test, and teardown. We schedule tests so the trailer is at our shop for the minimum required time.
Do you handle the National Board paperwork?
Yes for the R-stamp side of any repairs we perform during testing. For the DOT compliance inspection paperwork itself, we provide the inspector's report and inspection sticker per 49 CFR requirements.
Related services
R-Stamp Welding
Pressure vessel repair on petroleum transport tanks performed by R-Stamp certified welders. Done to ASME and National Board standards. Documented for terminal compliance and DOT inspection.
Learn more →Compliance Inspections
Annual DOT inspections, follow-up corrections, terminal-ready documentation. We get your tanks through inspection and back to the loading rack.
Learn more →Tank Remounts
Full tank remounts — removing your existing petroleum tank from an aging chassis, inspecting it, and mounting it on a new trailer. R-stamp certified, documented, defensible.
Learn more →Get the work scheduled.
Same-week appointments most weeks for fleet customers. Emergency response 24/7. Call or request an assessment and we'll get you scheduled.