46 CFR §52.25-15

1. (a)Fired thermal fluid heaters must be designed, constructed, inspected, tested, and stamped in accordance with the applicable provisions in this part.
2. (b)Each fired thermal fluid heater must be fitted with a control which prevents the heat transfer fluid from being heated above its flash point.
3. (c)The heat transfer fluid must be chemically compatible with any cargo carried in the cargo tanks serviced by the heat transfer system.
4. (d)Each fired thermal fluid heater must be tested and inspected in accordance with the requirements of subpart 61.30 of this subchapter.