Flowserve Nordstrom Dynamic Balance Plug Valve and Double DB Plug Valve - Manual (Page 21)

Flow Control
Nordstrom Valves
FCD NVENIM2005-01 Dynamic Balance ® Plug Valve and Double DB ® Double Isolation Plug Valve 21
4. If the valve is installed vertically, support may be required for the
Cover so that the internal parts, retained by the Cover, will not
fall out when the Cover Bolts are removed.
5. Remove the Cover Bolts. Remove the support piece and care-
fully remove the Cover. The Ball Seat, Spring, Diaphragms,
Gasket, Plug, etc., will now be exposed to view.
6. Carefully remove the Gasket and all traces of it from the valve
Body.
7. For valves 6" and larger, ensure the Thrust Ball and Ball Seat are
in place.
8. Apply a film of sealant on the entire surface of the large end of
the Plug.
9. Place the new Gasket into the counterbore of the Body.
10. Install the stainless steel (thin) Diaphragm.
11. Install the carbon steel (thick) Diaphragm.
NOTE: For stainless steel and alloy steel (WC9) valves, four of
the stainless steel (thin) Diaphragms and no carbon steel (thick)
Diaphragms are used.
12. Place the Thrust Button in the center of the Diaphragm.
13. Place individual O-ring Weatherseals around each Body
bolt hole.
14. Place the Cover over the Thrust Button and align the bolt holes
with the Body bolt holes.
15. Lubricate the Cover Bolts with a quality thread lubricant.
16. Insert the Cover Bolts but do not screw the bolts all the
way down. Ensure that the gaskets and diaphragms are not bent
or pinched.
17. Tighten the Cover Bolts, using the appropriate torque values
from Table 4 and the procedure for Tightening Cap Screws and
Nuts in the last segment of the Technical Data section. This will
ensure that the Gasket and Diaphragms are not damaged during
assembly.
18. Remove the Plug Adjusting Screw and apply a thread-locking
compound.
19. Insert the Plug Adjusting Screw into the Cover until the screw is
aligned with the inside of the Cover.
20. When new Diaphragms have been installed, it is necessary to
form them so that proper adjustment of the Plug can be made.
Deformation of the Diaphragms is achieved by the following
steps:
a. Insert the proper sized hex-head wrench into the hex hole in
the Plug Adjusting Screw.
b. Tighten the Plug Adjusting Screw to the appropriate “initial
torque” shown in Table 4, Plug Adjusting Screw Torques, in
the Technical Data section. Loosen the Plug Adjusting Screw
and tighten it to the same torque two more times.
c. Loosen the Plug Adjusting Screw one more time, and then
tighten it to the appropriate final torque as shown in Table 4.
21. If you did not install new Diaphragms, adjust the Plug as fol-
lows:
a. Tighten the Plug Adjusting Screw to a snug condition.
b. Loosen the Plug Adjusting Screw 1 ⁄
16
" to 1 ⁄
8
" of radial
movement.
22. Inject sealant: Refer to Problem C .
Cause D2: Non-compressible fluid trapped in port of Plug while in
the closed position.
Solution D2
Allow pressure to self-relieve over a period of time. If Cover leakage
continues, follow procedures as described in Cause D3 below.
Cause D3: Loose bolting
Solution D3
Tighten the Cover bolting to the torque and in the order listed in the
Technical Data section.
1. Loosen the Plug Adjusting Screw approximately 1/2 turn.
Tighten the Cover cap screws to the torque shown in Table 2 or
3 (Torque Values for Pressure Retaining Bolting) in the Technical
Data section.
2. Tighten the Plug Adjusting Screw until the Plug is tight in the
Body, and then loosen the Plug Adjusting Screw approximately
1/4 turn. The valve should be in the full open position.
3. Inject Sealant: Refer to Problem C.
4. If leakage continues, then it is probable that the Cover Gasket
and/or Diaphragms have been damaged.
a CAUTION: The Gasket and Diaphragms can be replaced
only when the valve is out of service. Procedures for
replacing the Gasket and Diaphragms are described in
Cause D1 above.