Understanding ASME Requirements

 June 1, 2018      Bradford White


What is ASME?

ASME stands for the American Society of Mechanical Engineers. Its purpose in the plumbing industry is to regulate the design and construction standards for commercial boilers and pressure vessels (water heaters and storage tanks).

Where is ASME required?

ASME certification is commonly required for job specifications in hospitals, schools, factories, and manufacturing plants. Please be aware that ASME requirements vary by state.


  • Vessels must be constructed of steel meeting ASME specifications built by an ASME certified welder.
  • Vessels must undergo a temperature and pressure test overseen by an ASME-certified inspector for a specified period of time.
  • Products must be built to ASME code at the factory, they cannot be “converted” in the field.
  • Products ship with a copy of the manufacturer’s ASME data report


Typically required on products with 1 or more of the following (varies by state):

  • Heat input of 200,000 BTU/Hr. (58kw) or higher
  • Water temperature of 210°F or above
  • Tank capacity of 120 gallons or more

This is one example of a seal or stamp that will appear on ASME approved products or their documentation. There are other versions depending on the type of ASME certification required.