AO Smith Mil-Spec Cryogenic Storage — 181 Gallon High-Pressure Vessel

What is the MAWP and capacity at service pressure?

The vessel is rated for 5000 PSIG with a capacity of 181 gallons. The listing does not specify whether 5000 PSIG is the MAWP or a working pressure, nor does it provide capacity figures at different fill pressures or temperatures for cryogenic service. Request the original design documentation or hydrostatic test records to confirm the MAWP and usable capacity for your intended service conditions.

What is the requalification or inspection status?

The listing does not provide any information about hydrostatic testing, requalification dates, or current inspection status. High-pressure vessels typically require periodic hydrostatic testing—intervals vary by jurisdiction and service type, commonly every 3 to 10 years for stationary ASME vessels. You should request all test records and determine what requalification work will be required before the vessel can be placed into service under your applicable code.

What should I inspect before putting it into service?

At a minimum, verify the integrity of all welds, the condition of the inner vessel if it's a vacuum-insulated design, and the functionality of all pressure relief devices and valve connections. Given the 1943 manufacture date, have a qualified inspector assess the vessel for any metallurgical degradation, previous repairs, corrosion (particularly in cryogenic service zones), and compliance with your current operating code. The 33'4" length suggests this is a horizontal configuration; check saddle supports and any areas where moisture could have accumulated over eight decades of service.