2001 ASME CNG Storage 2-pack –5,500 PSI, 20" x 10', CNG Volume 11,052 SCF

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

These vessels are ASME Section VIII, Appendix 22 certified with National Board registration (NB #6512 and NB #6513), which qualifies them for stationary installation at fixed facilities such as CNG fueling stations, industrial gas storage skids, and fleet depots. ASME vessels cannot be transported over the road when charged with gas—that requires DOT certification—but they are the standard for permanent, high-pressure bulk storage installations where capacity and working pressure exceed what DOT cylinders typically offer.

What is the MAWP and capacity at service pressure?

The Maximum Allowable Working Pressure (MAWP) is 5,500 PSI, and the combined CNG storage capacity for the 2-pack is 11,052 SCF at service pressure. Each vessel measures 20 inches in diameter by 10 feet in length and weighs approximately 1,230 lbs.

What is the requalification or inspection status?

The listing does not state whether these vessels have current hydrostatic requalification or when the last inspection was performed. ASME pressure vessels in CNG service are typically subject to periodic internal and external inspections per CGA, NFPA, and applicable state or local codes—intervals commonly range from 3 to 10 years depending on jurisdiction and risk assessment. You should request documentation of the most recent hydrostatic test, internal inspection report, and any ultrasonic thickness measurements from the seller.

What should I inspect before putting it into service?

Conduct a thorough external inspection for corrosion, dents, gouges, arc strikes, and any damage to nozzles, valve connections, and saddle/support points, as these can indicate stress concentration or material loss. Internally, check for corrosion, pitting, or deposits—CNG service typically keeps vessels dry, but contamination or moisture ingress during storage can cause localized damage. Verify the ASME data plate and National Board stamp are legible and match the documentation, confirm all pressure relief devices are in-date and properly sized, and arrange for hydrostatic retesting and ultrasonic thickness mapping if records are incomplete or outdated.