b'OILFIELD PLUG VALVE - LT - SP STYLE3 . 0 O P E R A T I O NAPV quarter turn plug valves have a taper seal. The inside body is tapered to ensure a uniform clamping action for the initial seal. As pressure is introduced to the valve, the plug and inserts are allowed to float downstream to act as a seal as the inside body wall is encountered. As pressure increases, the differential pressure becomes greater assisting the effectiveness of the seal. The torque then required is minimised due to the relationship between the seal and the bearing area.3.1 PRECAUTION DURING OPERATIONAt times it may be necessary to turn the valve when pressure is present. APV recommends the use of remote control Actuators for this purpose. In cases where this is not feasible, exposure time around pressured lines during valve operation should be kept to a minimum and only by experienced personnel.Before applying pressure, valves should be greased in both the opened and closed position. If valve is excessively hard to operate, becomes plugged, or does not operate properly it should be removed and not used until repairs are made.When opening a plug valve under pressure, the initial torque to start the stem turning is always greater than the moving torque. You must position your body to be able to compensate for this change.Never look into, or position yourself in the path of the exit flow of the valve.Condsider the exit position any plug valve, used for bleeding. This needs to be situated away from rocks or debris that may be picked up by the exit stream.If valve is slow to open or close, remove it from service. Do not hammer on the valves Actuator cap.Operation rate in excess of 42 feet per second be avoided. Rates above this will cause more rapid wear and erosion.Never alternate a valves service; acid service should never be followed by cold temperature service.If acid etching or erosion is present, the valve should be replaced.The pressure code as shown on each integral union connection nut should not be exceeded. To avoid failures this code should also be used when mating unions. All integral union connections must match (according to size, pressure rating, etc.). These connections must also match the service of the designated string they are installed in.Australian Pipeline Valve - Installation, Operation and Maintenance Manual 7'