Hello, I am a package engineer responsible for procuring a heating medium package (using hot oil). Unfortunately I am very confused about which standard I should be specifying for the heater. Some companies are offering packages built and stamped to ASME 1 while some are offering the package built to API 560. I know that ASME 1 is the power boiler standard used for the design/fabrication of water boilers so why are vendors building to ASME 1 over API 560 (this seems very common)? Does anyone know what the difference between an API 560 heater and an ASME 1 heater is?