UN-DOT-3AX-2538 — 109,000 PSIG High-Pressure Tube Trailer

What is the requalification status, and when is the next test due?

The listing does not state the last hydro test date or next due date. DOT-3AX cylinders typically require requalification every 3 or 5 years depending on service and original authorization; you'll need to verify the stamped test dates on the tubes and confirm compliance status with the seller before purchase.

What is the actual gas capacity at service pressure?

The listing states 660 gallon water capacity, but does not provide the gas capacity in SCF at the 109,000 PSIG service pressure. Request the calculated standard cubic feet capacity from the seller, as this depends on tube bundle configuration and compressibility factors at this extreme pressure.

What should I inspect on a used tube trailer before buying?

Verify all DOT markings and test dates are legible on each tube, inspect valves and manifolds for leaks or damage, check the ISO frame for cracks or corrosion especially at mounting points, and confirm landing gear and road equipment function. Request current or recent ultrasonic thickness test results if available, as wall thinning from internal corrosion can affect remaining service life even if hydro is current.