DUCTILE IRON FLANGED GATE VALVE
FIGURE 751
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INSTALLATION, OPERATION & MAINTENANCE INSTRUCTIONS
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•
Check the pipeline and supporting flange to ensure that the pipeline is
free of foreign matter, the flange is clean, and there are no burrs or pits
to avoid leakage.
•
Make sure the connecting pipe has adequate support. Improper
support can lead to valve deformation, leakage, operational inefficiency
and early maintenance issues.
•
When installing the gate valve, make sure that there is enough space
around the handwheel to operate the valve easily and safely, and make
sure that the valve stem has enough space to rise when the valve
is opened.
•
Ensure that the bolt and gasket material are compatible with the valve
body material and pressure rating.
•
With proper support, align the valve flange holes with the pipe
flange holes.
•
For ring washers, insert two to four bolts into the lowest bolt holes.
•
Insert a suitable gasket between the flanges and center them.
For ring spacers, use the inserted bolts to center the spacer.
•
Insert and tighten all bolts and nuts. Care should be taken to ensure
that the flanges are parallel.
•
Using a cross pattern (star pattern), tighten each bolt evenly to ensure
even shim loading. The ends of the tightening bolts should protrude
evenly from each nut (see Figure 4).
•
After the valve is installed, re-check all the bolts and nuts of the
connecting flanges and re-tighten them if they are found to be loose.
OPERATION
•
Gate valves are not designed for throttling (modulating) service and should be used in the open or closed position. Prolonged use in
the partially open or closed position may result in the erosion of the wedge and/or seat. This position may also cause a “chatter” noise
in the line or cause damage to the valve.
•
For gate valves, turn the hand wheel counterclockwise to open the valve. Turn the hand wheel clockwise to close the valve.
Do not use pipe extensions (cheater bars) to operate the valve as this may damage seat surfaces, yoke or stem.
•
For gate valves, on a new valve or a valve that has had new packing installed, the hand wheel torque may be relatively high.
This high torque will diminish to a reasonable level after the valve has been operated several times. Hand wheel operating torque
also depends on the type and size of each valve and its position. Note that the operating torque is high when opening a fully closed
valve or when closing the valve and near the end of valve travel.
•
For gate valves, sometimes material in the line can get stuck between the disc and seating area. Should this happen, re-open the
valve to allow the process fluid to clear the material. If the condition persists, it may be necessary to shut down the line and inspect
the interior of the valve.
(10)
8. If
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f the packin
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ng leaks, turrn the gland
d nut (10) eevenly in 1//4 turn increements until the
Figure 4
Tightening pattern
Table 1
Closing torque and turns to open
2.5"
3"
4"
6"
8"
10"
12"
Closing torque ft/lbs
≤50
≤55
≤77
≤110
≤150
≤185
≤225
Turn
11±0.5
10±0.5
13±0.5
19.5±0.5
26±0.5
32±0.5
38±0.5
300PSI UL/FM OS&Y FLANGED GATE VALVE