Flowserve 50165 Nordstrom Figure - Manual (Page 26)

Nordstrom Figure 50165 and 50169 Dynamic Balance Iron Plug Valve FCD NVENIM2006-00 – 09/05
26
Valve Maintenance: Troubleshooting
This section lists common problems you may encounter with the Dynamic Balance plug valve, the
probable causes, and solutions that should remedy the situations. The listed procedures are intended to
serve as guides to remedy conditions you may encounter when performing maintenance on your valve.
The procedures, as well as information shown in the Tables of this manual are based on factory valve
assembly procedures. Precise estimates of field conditions are not feasible. Judgement and experience
must be applied when working on valves in actual field site conditions.
It is highly recommended that sealant be injected into the valve prior to proceeding with valve adjust-
ment or repair. Gauge scenarios, as detailed earlier, will help you focus on specific solutions to remedy
your valve problem. Your sealant injection equipment should be operating properly prior to diagnosing
valve problems.
a Caution: If a non-compressible fluid is trapped in the center cavity of the plug, when the valve
is in the closed position, injecting sealant at high pressures or high volumes can cause the plug
to lock in place. This can also cause the Cover Bolts to yield, thus producing Cover leakage.
Problem: Valve seat leakage
Cause 1: Insufficient sealant in the valve
Solution: The lack of sufficient sealant to adequately fill and pressurize the sealant system is the most
common problem associated with seat leakage. Inject the correct amount of sealant into the valve and
again check for seat leakage.
Cause 2: Plug adjustment is too loose
Solution: Loose plug adjustment may also be recognized by the valve operating torque being lower than
normal. If possible, operate the valve a number of times prior to adjusting the Plug Adjustment Screw
and make adjustments using the following procedures:
1. Remove the hex head cap screw or thin metal plate located on the Bottom Cover of the valve to
expose the Plug Adjustment Screw. After the valve is assembled at the factory, the Plug Adjusting
Screw and valve cover is marked by chisel point to locate the position of factory adjustment. Check
the Plug Adjustment Screw for tampering. If the Adjusting Screw has been moved in counter-clock-
wise direction, you should retighten to the factory adjustment mark.
2. Insert the proper size hex head wrench into the hexagonal shaped hole in the Plug Adjustment
Screw.
note: During factory assembly, thread-locking compound is applied to the Plug Adjustment Screw.
The screw may be initially difficult to turn.
3. Operate the valve back and forth through its 90° operating range, and simultaneously tighten the
Plug Adjusting Screw. This action will help disperse previously injected valve sealant. If operating
conditions prevent rotating the plug completely through its 90° operating range, you can rotate
the plug through a 20° arc to disperse the sealant. Continue to tighten the Adjusting Screw until a
noticeable torque increase makes the plug harder to turn. This will indicate you have metal-to-metal
contact between the body and plug.
a Caution: Over-adjustment of the Plug Adjusting Screw will lock the plug into the body
taper.