All defined boilers and unfired pressure vessels are regulated unless specifically exempted at 680 IAC 2-1-2(f).
Note: The parameters that determine how an object is defined or is regulated pertain to its specific location, size, pressure, use and ownership. A licensed inspector should be consulted with specific information to make this determination.
Boilers and pressure vessels at 680 IAC 2-1-5 are exempt from the requirements for inspection and certification; however they are not exempt from the requirement for ASME standard construction. http://www.in.gov/legislative/iac/iac_title?iact=680&iaca=2