Flowserve 50165 Nordstrom Figure - Manual (Page 25)

25
Nordstrom Figure 50165 and 50169 Dynamic Balance Iron Plug Valve FCD NVENIM2006-00 – 09/05
flowserve.com
4. There are four gauge scenarios that will help you determine valve seat leakage problems. Once you
have identified the applicable gauge scenario, you can apply the appropriate maintenance proce-
dures, found in the specific valve maintenance manual, to ensure your valves are operating at their
peak.
• Gauge Scenario one: The gauge does not indicate a pressure increase above the initial pressure
required to inject sealant into the valve. Assuming your injection equipment is operating correctly,
there are two possible problems: a) the sealant system is not full, or b) the seat is leaking.
Leakage may be caused by too loose an adjustment or damage to the valve’s seating areas.
• Gauge Scenario two: As sealant is injected, the gauge indicates a gradual increase in pressure
until an initial plateau is reached, then at some point the pressure increases to a higher plateau
and abruptly falls back to a lower level. This scenario indicates that the valve is receiving sealant
properly, the valve sealant system has filled, and the plug has moved off the seat. Even though
this scenario shows the plug has moved off the seat, it is still possible that the valve may be
difficult to operate. Operation difficulties may be caused by a) too tight an adjustment, b) stem
corrosion, or c) gearing problems on gear operated valves.
• Gauge Scenario three: This scenario is much like Scenario Two except the sealant pressure
gauge reaches a plateau and remains at that point as the injection equipment is operated, even
after you have injected more than enough sealant to fill the valve. This scenario signals one of
two quite different conditions. If the plug is not locked in the body taper, then the plug may be
unseated and additional sealant is simply bypassing the plug. This is normal and indicative of a
properly maintained and well pressurized valve. However, if the plug is locked in the taper and
cannot be operated, this indicates that the plug or valve body may be damaged and sealant is
bypassing the sealing surfaces. In Scenario Three it is also possible for the valve to be difficult to
operate. The likely causes are the same as with Scenario Two: a) too tight an adjustment, b) stem
corrosion, or 3) gearing problems on gear operated valves.
• Gauge Scenario Four: The gauge indicates a continual rise in pressure as sealant is injected, but
never indicates a pressure decrease. This scenario indicates three possible problems: a) the valve
sealant fitting is faulty, b) the sealant system is blocked, or c) the plug has seized in the body
taper.
5. Open and close the valve several times while continuing to inject sealant. If conditions do not allow
you to fully open or close the valve, rotate the plug back and forth (approximately 20 degrees)
several times.
6. After you have completed the injection of sealant, relieve the pressure within the injection equip-
ment and remove it from the Sealant Fitting.