Flowserve Nordstrom Dynamic Balance Plug Valve and Double DB Plug Valve - Manual (Page 18)

Flow Control
Nordstrom Valves
18 Dynamic Balance ® Plug Valve and Double DB ® Double Isolation Plug Valve FCD NVENIM2005-01
4. Loosen the Plug Adjusting Screw 1 ⁄
8
turn. If possible, the valve
should be in the full open position for final plug adjustment.
5. Inject sealant (see Problem C). You should see a higher pressure
reading on the gauge. If you still do not get a pressure increase
on the gauge, repeat Steps 3 and 4. If a second attempt at plug
adjustment is unsuccessful, it is likely there is a damaged area
on the Plug or Body-seating surface. Refer to Cause A3 below.
6. Replace the Plug Adjusting Screw cover.
Cause A3: Damaged Plug
Solution A3 (straightway valves only - not applicable to Multi-
ports)
A simple way to overcome a damaged Plug is to rotate the Plug
180° to place the upstream seat into the downstream position. This
procedure is a temporary solution to the seat leakage problem, and
the valve should be identified for remanufacture or replacement.
For a Wrench-Operated Valve:
1. Loosen the Plug Adjusting Screw 1/2 turn.
2. With the valve in the full open or full closed position, remove the
Retaining Ring and the Stop Collar.
3. Rotate the valve Stem 180°.
4. Replace the Stop Collar and the Retaining Ring.
5. Adjust the Plug as described in Valve Sealant Leakage, Cause A2
above, Steps 3 through 6.
6. Inject sealant: Refer to Problem C.
For Gear-Operated Valves:
1. Loosen the Plug Adjusting Screw 1/2 turn.
2. With the valve in the full open position, remove the Gear Hous-
ing Bolting.
3. Turn the Gearing Handwheel clockwise. The Gear Housing will
move counterclockwise.
a CAUTION: Do not damage the Gear Housing Gasket
while rotating the gearing.
4. Turn the Handwheel until the Gear Housing bolt holes align with
the next hole in the Gear Flange.
5. Replace two of the housing bolts to hold the Gearing firmly.
6. Turn the Handwheel counterclockwise until the Gear Segment
contacts the valve stop.
7. Repeat steps 3 and 4 until the Gear Housing has been rotated
180 degrees.
8. Replace the Gear Housing bolting.
9. Inject sealant: Refer to Problem C.
10. Adjust the Plug as described in Valve Seat Leakage, Cause A2
above, Steps 3 through 6.
Problem B: Operation difficulties
Cause B1: Insufficient sealant in the valve
Solution B1
The lack of sufficient sealant to adequately fill and pressurize the
sealant system is the most common problem associated with a valve
being hard to operate. Inject the correct amount of sealant into the
valve and again check the operating torque of the valve.
Cause B2: Plug adjustment too tight
Solution B2
Loosen the plug adjustment.
1. Loosen the Plug Adjusting Screw 1 ⁄
8
turn.
2. Inject sealant into the valve.
3. The valve should now be operable.
Cause B3: Minor Stem corrosion (wrench-operated valves)
Solution B3
Lubricate the Stem-to-Gland joint.
1. Remove the Retaining Ring and Stop Collar.
2. Remove the Weatherseal and inspect it for signs of damage. If
the Weatherseal is damaged, replace it. Check for corrosion on
the stem or internal surface of the gland.
3. If there is corrosion, dam the area around the Stem-to-Gland
joint with a heavy grease or Nordstrom Stick Grade sealant.
4. Introduce penetrating oil into the Stem-to-Gland joint. Allow the
penetrating oil to saturate for a minimum of 24 hours. Periodi-
cally operate the valve.
5. If the valve becomes operable, clean the Stem-to-Gland joint of
excess penetrating oil.
6. If penetrating oil does not free the valve, clean the Stem and
inside surface of the Gland, as described in Cause B4 below.
7. Coat the area under the Weatherseal with lithium-base grease.
8. Replace the Weatherseal, Stop Collar, and Retaining Ring.