Boiler Approvals, Stamps, and Local Jurisdiction Review – Application Engineering

Approval/Mark	Application
ASME S	Power boilers and economizers built to Section I
ASME H	Heating boilers
ASME U	Other pressure vessels such as blowdown separators
National Board	Authorized inspection, witnessed hydrostatic test, registration number
CRN	Required Canadian registration; installation province must be known before manufacture
CSA B51 / TSSA	Canadian factory pressure equipment and inspection requirements
UL / c-UL-us	Packaged boiler certification for U.S. and Canadian markets
FM	Project/installer application and insurer review; packaged design is not simply “FM approved” as a universal product statement

Always perform an AHJ review