ANY VALVE TO BE USED IN A GAS TRANSMISSION SYSTEM PIPELINETHAT HAS SHELL COMPONENTS MADE OF DUCTILE IRON SHALL NOT BEOPERATED AT A PRESSURE ABOVE ______ OF THE PRESSURE RATING OF A COMPARABLE STEEL VALVE.

ANY VALVE TO BE USED IN A GAS TRANSMISSION SYSTEM PIPELINETHAT HAS SHELL COMPONENTS MADE OF DUCTILE IRON SHALL NOT BEOPERATED AT A PRESSURE ABOVE ______ OF THE PRESSURE RATING OF A COMPARABLE STEEL VALVE.