Val-Matic Rubber-Seated Ball Valve - Manual (Page 5)

5
prevent time lost searching for leaks, where feasible, it
is recommended that excavations for buried valves not
be backfilled until after pressure tests have been
made. Seat leakage can occur from foreign material in
the line. If this occurs, open the valve 5°–10° to obtain
high-velocity flushing action, and then close. Repeat
several times to clear the seats for tight shutoff. Seat
leakage can result from a rotational shift in position of
the ball with relation to the body seat. Readjust the
closed end stop in accordance with these instructions.
OPERATION
Do not permit the use or operation of any valve at
pressures above the rated pressure of the valve. Do
not exceed 300 ft-lb input torque on worm gears or 450
ft-lb input torque on traveling-nut actuators with wrench
nuts. Do not exceed 200 lb rim pull for handwheels or
chainwheels. If portable auxiliary actuators are used,
size the actuator or use a torque-limiting device to
prevent application of excessive torque. If an oversize
actuator with no means of limiting torque is used, stop
the actuator before the valve is fully opened or closed
against stops and complete the operation manually. Be
sure to check the actuator directional switch against
the direction indicated on wrench nut, handwheel, or
records before applying opening or closing torque.
If a valve is stuck in some intermediate position
between open and closed, check first for jamming in
the actuator. If nothing is found, the interference is
inside the valve. In this case, do not attempt to force
the valve open or closed, because excessive torque in
this position can severely damage internal parts.
Operation of the valve rapidly may cause pressure
surges and damage to the valve and the pipeline,
especially on long pipelines. Do not bypass power
actuator speed control devices. When using a power
tool to operate a manual actuator, maintain an input
shaft speed typical of manual operation.
INSPECTION PRIOR TO INSTALLATION
Make sure flange faces, joint sealing surfaces, body
seats, and ball resilient seats are clean. Check the
bolting attaching the actuator to the valve for loosening
in transit and handling. If loose, tighten firmly. Open
and close the valve to make sure it operates properly
and that stops or limit switches are correctly set so that
the valve seats fully. Close valve before installing to
prevent damage to seating surfaces.
INSTALLING
1. Handle valves carefully using lifting lugs provided
when positioning, avoiding contact or impact with
other equipment, vault walls, or trench walls.
2. Valves are to be installed in accordance with these
instructions. To maintain the integrity of the valve, it
is important to avoid subjecting the valve to pipe
loads that could drive the valve out of round. The
valve is designed for vertical support from a
concrete support or similar structure, see Figure 5.
The valve support pads should not be anchored to
the concrete support but instead rest on a slide
plate to avoid axial pipe loads. Piping to and from
the valve should be adequately supported and
controlled. Piping design requirements should
include allowable flange loadings, thermal
expansion and contraction, and differential
settlement.
3. Foreign material in a ball valve can damage the
rubber seat when valves are operated. Be sure
valve interiors and adjacent piping are cleaned of
foreign material prior to making up valve to pipe
joint connection.
4. Where practical, valves in buried installations should
be located in vaults. Buried valves installed with
valve boxes shall be installed so that the valve box
does not transmit shock or stress to the valve
actuator as a result of shifting soil or traffic load.
5. Prepare pipe ends and install valves in accordance
with the pipe manufacturer’s instructions for the
joint used. Do not deflect pipe-valve joint. Do not
use a valve as a jack to pull pipe into alignment.
The installation procedure should minimize the
bending of the valve/pipe connection with pipe
loading.
6. For horizontal pipelines, the valve and adjacent
piping must be supported and aligned to prevent
cantilevered stress on the valve. Lower valve into
line using slings or hooks in the integrally cast body
lifting lugs. Lubricate the flange bolts or studs and
insert them around the flange. Lightly turn bolts
until gaps are eliminated.
7. The torquing of the bolts should then be done in
graduated steps using the cross-over tightening
method. Recommended lubricated torques for use
with resilient gaskets (75 durometer) are given in
Tables 2 and 3. Do not exceed bolt rating or crush
gasket more than 50 percent of its thickness.
8. Make sure the valve ball, when opened, will not
contact adjacent valves.
CAUTION: The use of raised-face flanges
or excessive bolt torque may
damage valve flanges.