Valve Torque Calculations 712i22

February 8, 1996 VALVE TORQUE CALCULATIONS 1) Calculate the packing surface area (A): A = ( D2 - d2 ) π 4 Where: D = Stuffing box bore (in) d = Stem diameter (in) 2) Determine the load factor (LF): When using a 9000-EVSP Simplified set or a 98/GRAPH-LOCK® set, LF = 1.5 X System Pressure or 3800 psi (whichever is greater) When using a braided packing set design, LF = 1.5 X System Pressure or 5500 psi (whichever is greater) 3) Calculate the force on the gland follower (F): F = A X LF Where: A = Packing surface area (sq. in.) LF = Load factor (psi) 4) Calculate the gland bolt torque (T): (resultant value in units of in-lbs.) T = ( 0.2 X F X Φ ) B Where: F = Force exerted by gland (lbs) Φ= Gland Bolt diameter (in) B = Number of gland bolts

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