High Pressure Tube Trailer - Type 1, 2400 psi, water volume 699 cu ft. Retested 12/2023 - Nitrogen, CNG, Hydrogen ...

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

The high-pressure inspection was completed in December 2023 and the annual DOT inspection on 03/27/2024. DOT-SP 14584 tubes typically require hydrostatic retest every 5 years and annual visual inspections; you'll need to verify the specific retest interval with the seller and confirm it against the special permit requirements.

What is the actual gas capacity at service pressure?

The water volume is 699.3 cubic feet at a marked service pressure of 2400 psi, but note that Tube 5 (SN 4709-44) has been rejected and removed from service, reducing the effective capacity. The listing does not specify the remaining in-service water volume or the actual gas capacity at pressure; you'll need to request tube-by-tube volumes and calculate gas capacity based on the compressibility factor for your intended service gas.

What gas service has it been in, and what can it be converted to?

The trailer has been in Nitrogen service under DOT-SP 14584 and is currently configured for Nitrogen. According to the listing, it can be adapted for CNG, Hydrogen, or other high-pressure gases with small adjustments, though you should verify special permit coverage and any material compatibility requirements for your intended gas—particularly for hydrogen service, which may require additional tube inspections for embrittlement.

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

Review the individual tube history files for each cylinder, particularly the hydrostatic test reports, neck thread inspection records, and any ultrasonic or eddy current testing data. Inspect the piping manifold for corrosion or damage, verify all valves operate smoothly without leaks, check the undercarriage and axles for wear, and examine the support cradles and tie-down hardware. Since one tube has already been rejected on this unit, determine why it failed and whether the remaining tubes show similar degradation patterns.