Thermal Oil Heaters in Australia and New Zealand 1

[anoneeinche]

Hello All

My company supplies equipment that uses thermal oil heating systems, typically using something like Duratherm HF, Therminol 55/66, etc. While we do not design thermal fluid heating systems, we sometimes supply them, and will work with a sub-contracted vendor who specializes in thermal fluid heating systems. The units supplied in the past by my company have been designed using US engineering standards.

We are currently investigating thermal oil heating systems for applications in Australia and New Zealand, but there is a concern over the thermal fluid flash points. In the US, it is acceptable to operate thermal fluid heating systems above the heat transfer fluid's flash point, provided the necessary design changes to the equipment are made (ASME code expansion tank, etc)

I've been told that thermal oil heaters cannot operate above the fluid flash point in Australia. Is this true? Are there any other major design implications that apply in Australia? For the current application, relatively high thermal fluid temperature is required, and it is only a few degrees less than the flash point.

Thank you!

 

[georgeverghese]

The main safety implication with hot oil operating above flash point is with minor unavoidable leaks from flanges and instrument connections - see electrical hazardous area classification requirements in AU / NZ for cases when systems operate in HAC Zone 2 environments. So you can operate at above flash point if you comply with AU/ NZ HAC requirements, the main one being a Zone 2 motor for the hot oil pump.
Good engineering practice would be to also use Class 300lb flanges for hot oil throughout as a minimum, preferably RTJ. And stay well clear of mag drive pumps; use API Plan 51 or 52 for hot oil pump shaft seals. This website is riddled with negative Operations feedback on all sorts of operating problems with mag drive pumps. Vaguely recall there is some credit you get for Plan 51/ 52 shaft seals on the requirement for Zone 2 hot oil pump motor - check.