“Indirect heat exchanger” means combustion equipment in which the flame and/or products of combustion are separated from any contact with the principal material in the process by metallic or refractory walls which includes, but is not limited to, the following:

1. (a) Steam boilers;
2. (b) Vaporizers;
3. (c) Melting pots;
4. (d) Heat exchangers;
5. (e) Column reboilers;
6. (f) Fractioning column feed preheaters;
7. (g) Reactor feed preheaters; and

8. (h) Fuel-fired reactors such as:

   1. (1) Steam hydrocarbon reformer heaters; and
   2. (2) Pyrolisis heaters.

Source. (See Revision Note at chapter heading for Env-A 3200) #11001, eff 1-1-16