5500 PSI 3-Pack CNG Storage Tubes –ASME Pressure Vessels

Is this ASME or DOT rated, and what does that allow me to do with it?

These are ASME-certified vessels with National Board numbers (#4380, #4095, #4206), which qualifies them for stationary installation at CNG fueling stations or industrial gas storage facilities. ASME vessels are designed for fixed-location service and cannot be transported filled over the road, which requires DOT certification. If you need mobile or vehicle-mounted storage, you'll need to source DOT-compliant cylinders instead.

What is the MAWP and capacity at service pressure?

The MAWP is 5,475 PSIG and each cylinder holds 85 CuFt water volume. At typical CNG station operating pressure (3,600 PSIG for fast-fill or 3,000 PSIG for time-fill), you'd store roughly 65-70% of the rated capacity depending on cascade configuration, but verify actual gas capacity calculations based on your specific fill protocol and target vehicle pressure.

What is the requalification or inspection status?

The listing does not provide current inspection or requalification records. For ASME CNG storage vessels, National Board requalification is typically required every 3-5 years depending on jurisdiction and original code of construction, so with a 1995 manufacture date you should request documentation of the most recent external visual inspection, UT thickness testing, and hydrostatic test results before purchase.

What should I inspect before putting it into service?

Have an authorized inspector perform UT thickness mapping on the seamless steel shell to verify remaining wall thickness meets code minimums, particularly in areas that may have seen internal corrosion from moisture carryover during CNG service. Inspect all threaded ports and flange faces for thread damage or erosion, check skid welds and mounting hardware for fatigue cracks, and verify the MDMT rating of -40°F is adequate for your installation climate—if you're in a colder region, the vessel may require insulation, heat tracing, or a fitness-for-service evaluation.