(a) For internal inspection, manhole and handhold plates, and washout plugs shall be removed as required by the marine inspector and the furnace and combustion chambers shall be thoroughly cooled and cleaned. Portable obstructions shall be removed as necessary for proper access.

(b) In preparing the boilers for the hydrostatic test, they shall be filled with water at not less than 70 °F. and not more than 160 °F. for watertube boilers, and not more than 100 °F. for firetube boilers. The safety valves shall be secured by means of gags or clamps.