Large diameter and relatively high pressure relief valve

A relief valve for connection with a large diameter conductor containing fluid under greater than atmospheric pressure, comprising:

• a valve body having axially spaced longitudinally aligned openings,
• one said aligned opening forming an outlet port of smaller diameter than the other said aligned opening,
• said body having a lateral opening forming the inlet port of a fluid passageway through the body;
• sleeve means projecting axially inward from each said aligned opening including an outlet port sleeve of equal diameter with respect to the outlet port and a guide sleeve of greater diameter than the outlet port;
• a centrally bored cap having an annular outstanding flange for closing the outward end of the guide sleeve;
• piston means including:
• an apertured guide piston slidable in said guide sleeve forming a sleeve chamber and closing its end opposite said cap against upstream fluid pressure;
• an outlet piston axially connected with said guide piston and having an outer diameter closely received by said outlet port sleeve for normally closing the latter against upstream fluid pressure;
• a piston rod projecting outwardly through the sleeve end cap opposite the outlet port;
• and,
• collapsible pin means including a pin having a predetermined buckling point axially supported by the outwardly projecting end of the piston rod for maintaining said piston means in fluid passageway closed position while the upstream fluid pressure differential on said pistons is less than the buckling point of the pin in accordance with Euler's law.

A relief valve for connection with a large diameter conductor containing fluid under greater than atmospheric pressure, comprising:

• a valve body having inlet and outlet ports defining a flow passageway adapted to be interposed in the conductor;
• piston means including spaced-apart pistons slidably supported by the body and having unequal surface areas exposed to upstream fluid pressure for normally closing the passageway when the upstream fluid pressure is below a predetermined value and having other equal surface areas exposed to and balancing downstream fluid pressure;
• a piston rod projecting outwardly of the body;
• and,
• collapsible pin means including a pin having a predetermined buckling point axially supported by the outwardly projecting end of the piston rod for maintaining said piston means in fluid passageway closed position while the upstream fluid pressure differential on said pistons unequal surface areas is less than the buckling point of the pin in accordance with Euler's law.