A. A hobby or model boiler must be attended by a person reasonably competent to operate such boiler when in operation. For the purposes of this section, a hobby or model boiler may be considered as not being in operation when all of the following conditions exist:
1. The water level is at least one-third of the water gauge glass;
2. The fire is banked and the draft doors closed or the fire is extinguished; and
3. The boiler pressure is at least twenty pounds per square inch below the lowest safety valve set pressure.
B. All welding performed on hobby or model boilers shall be done by an “R” stamp holder in accordance with the inspection code of the National Board of Boiler and Pressure Vessel Inspectors.