51. Platform characteristics: Upright crucible furnaces with crown plates elevated more than 300 mm above the surrounding floor shall be equipped with platforms, except when the crucibles are transported by mechanical means exclusively. These platforms shall be:(a) constructed of metal and have a non-slip surface;
(b) of sufficient width for the safe operation of the furnace;
(c) extending along the front and sides of the furnace flush with the crown plate;
(d) provided with guardrails; and
(e) clear of any obstructions and dry.