Similarities and Differences Between 420 lb. ASME and DOT Tanks

Manchester’s 420 pound ASME tanks and 420 pound DOT tanks are similar in the following ways.

• Capacity
• Can be transported with 80% of the total container volume
• Powder coating system – improves the durability
• Vacuum pre-purged
• High density polyethylene (plastic) or steel lids
• Lifting lugs

However, the ASME tanks are usually the preferred choice due to their key differences from the DOT tanks. ASME tanks are tanks that meet the standards set by the American Society of Engineers. That’s where they get their designation of ASME.

420 lb. ASME Tanks

• No retesting period
• Heavier than DOT tanks of the same size
• Thicker steel provides longer life
• Data plate markings
  • Intended service (AG or UG)
  • Water capacity
  • Design working pressure
  • “This Container Shall Not Contain a Product Having a Vapor Pressure in Excess of __ Psig at 100 degrees F.”
  • Outside surface area
  • Year of Manufacture
  • Serial Number
  • ASME Code
  • Stationary ASME tanks are different than mobile ASME tanks in that they are not designed to be moved when they are legally full of gas.
  • Location
    • Must set at least 10 feet from external source of ignition, intake to direct vented gas appliance, or intake to a mechanical ventilation system
    • No minimum distance between two tanks
    • 5 foot minimum distance to openings below the top of the tank

DOT tanks are governed by a different set of standards. The Department of Transportation sets the standards for the transportation of hazardous chemicals and so the tanks that transport them have to be under strict regulation.

420 lb. DOT Tanks

• DOT retest periods are 12 years after manufacturing, then each 5 year period thereafter if done visually
• Portable tanks normally used for Temporary Service at construction sites or for emergency services at a customer’s site
• Inscribed on the collar of tank
  • Design code
  • Water capacity
  • Retest date
  • Tare weight
  • Dip tube length
  • Location
    • 10 foot minimum from external source of ignition, direct vent, or mechanical ventilation system
    • 3 foot minimum distance to openings below the top of the tank

Steven Novak

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