The preferred embodiment comprising a truncated cone valve plug, or a truncated cone with curved sides as in the tractrix valve is described. A step is fabricated into the large end of the valve plug.Plug Valves A secondary seal, called a Veri-Seal, is placed on the large end of the valve plug on the step at an intermediate location between the outer diameter of the plug and the stem. Pressure forces acting downward on the step on the top of the valve plug balance the pressure forces acting upward in the channel through the valve plug. API Cast Steel ValvesBy placing the Veri-Seal at this intermediate location on the top of the plug, the spring force can be minimized and the resulting torque to open and close the valve is consequently reduced.GLOBE VALVE A plug valve consisting of a valve body and a valve plug, a means to force said valve plug against said valve body to produce a primary seal, said valve plug having a large end, said large end having an outer diameter, said valve plug having a small end, and said valve plug having a channel through said valve plug for fluid communication, a pivot attached to said small end of said valve plug, a valve stem attached to said large end of said valve plug, a step on said large end of said valve plug, a secondary seal on said step at an intermediate location between said outer diameter of said large end of said valve plug and said valve stem for the purpose of balancing internal forces acting on the valve plug and thereby reducing opening and closing torque of the plug valve. The purpose of the plug valve is to contain fluid within the pipeline, exercise control over the starting and stopping of the fluid in the pipeline, hold the internal pressure within the plug valve, and prevent leaks to the surrounding environment. Prior art uses heavy spring forces to hold the plug against the body of the valve to ensure that the plug valve is leak tight. Plug valves are very hard to open and close because of the large spring forces employed to overcome unbalanced internal forces within the plug valve. Because the plug is tapered, there is slightly more area on top of the channel through the plug than on the bottom of the channel. As a result, the internal pressure produces an unbalanced force caused by the pressure acting on the larger area and this unbalanced force acts toward the larger end of the plug. It tends to try to push the plug away from the body of the valve, which, if allowed to happen, would allow leaking of the valve through the seat. To overcome this force unbalance, a somewhat higher spring force is needed. Since opening torque depends on the spring force, a larger spring force results in a higher torque required to open and close the valve. This level of torque makes it difficult to open and close the valve, especially by women or disabled workers. When an actuator is used to open and close the valve, usually a large, expensive actuator is needed. Clearly, a means is needed to lower the required torque on a plug valve while maintaining the valve leak tight.

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