Failure Probable Cause Corrective Action
Valve moves to failure position, exces-
sive air bleeding from transfer case
1. Failure of cylinder actuator O-ring 1. Replace actuator O-ring
2. Failure of sliding seal assembly in cylinder
actuator
2. Repair or replace sliding seal assembly
Jerky shaft rotation
1. Overtightened packing
1. Retighten packing box nuts to slightly over finger-tight for V-ring
packing, 14 ft-lbs/19 Nm for braided packing.
2. Improper adjustment of lever arm on shaft
causing arm to contact transfer case
2. Redjust lever arm (see step 1 in Actuator Remounting)
3. Cylinder wall of actuator not lubricated 3. Lubricate cylinder wall with silicone lubricant
4. Worn piston O-ring allowing piston to
gallon cylinder wall
4. Replace O-ring; if galling has occurred replace all damaged parts
5. Worn actuator stem O-ring causing
actuator stem to gall on stem collar
5. Replace O-ring; if actuator stem is galled replace it
6. Worn (or damaged) thrust bearings, shaft
bearing or packing followers
6. Disassemble and inspect parts; replace any worn or damaged parts
Excessive leakage
1. Improper adjustment of external stroke
stops
1. See Actuator Remounting
2. Improper seat adjustment 2. See Seat Replacement
3. Worn or damaged seat 3. Replace seat
4. Damaged plug seating surface 4. Replace plug
5. Improper handwheel adjustment acting as
limit stop
5. Adjust handwheel until plug seats properly
Leakage through line flanges
1. Dirty line gasket surfaces 1. Clean gasket surfaces and reinstall valve
2. Improper sealing of line flanges
2. Tighten line flanges evenly and completely (see Table 1 for proper
torque)
3. Flange or pipe misalignment 3. Reinstall valve in line; check piping system
Leakage through packing box
1. Loose packing box nuts
1. Tighten packing box nuts to slightly over finger-tight for V-ring
packing, 14 ft-lbs/19 Nm for braided packing.
2. Worn or damaged packing 2. Replace packing
3. Dirty or corroded packing 3. Clean body bore and stem, replace packing
Valve slams, wont open, or causes
severe water hammer
1. Improper valve installation 1. See step 2 in Installation and correct flow direction
Shaft rotates, plug remains open or
closed
1. Broken shaft
1. Replace shaft, make sure plug does not overstroke and contact
plug stop
Actuator operates, shaft does not rotate 1. Broken internal actuator parts 1. Refer to appropriate actuator maintenance instructions
Leakage through bonnet joint; leakage
from end post
1. Loose bolting or damaged gasket 1. Tighten bolting as recommended in Table II
2. Dirty gasket surfaces
2. Clean gasket surfaces, replace gaskets and retighten bolting per
Table II
3 - Air Action 4 - Pipe Configuration 5 - Actuator Orientation 6 - Shaft Direction
O Air-to-open - ATO L Left Hand Mounting L Left U Shaft Upstream
C Air-to-close - ATC R Right Hand Mounting R Right D Shaft Downstream
D Flow Down T Top (Default)
U Flow Up B Bottom*
AT
3 4 5 6
* Not available on diaphragm actuators
15 Pipe Mounting Orientation Codes
16 Troubleshooting
15
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