-6-
b. After Actuator installation, valve should be check for valve stem alignment. Angular
or linear misalignment will result in high operational torque and unnecessary wear on
the stem seal
8. Maintenance
8.1. Maintenance Frequency
User should determine the maintenance frequency depending on specific application. If
there is sign of leakage from the stem, it is time to replace the stem sealing components.
If there is sign of internal leakage, it is time to replace the seats and gasket components.
Life of the valve can be maximized if the valve is used within the rated range, in
accordance with pressure, temperature, and corrosion data
8.2. Disassembling and Cleaning the Valve
Ball valve can trap fluids in ball cavity when it is in the closed position. If the valve has
been used in hazardous media, it must be decontaminated before disassembly.
a. Relieve the line pressure
b. Place valve in half-open position and flush the line to remove any hazardous material
from valve
c. All persons involved in the removal and disassembly of the valve should wear proper
protective clothing, such as face shield, glove, apron, etc
8.3. Replacing Seats and Joint Gaskets
Seat and joint gaskets should be replaced at the same time. Once the valve is
disassembly for seat service, the gasket should also be replaced to ensure proper body
sealing
a. Follow the direction on Disassembling & Cleaning the valve. Make sure the pipeline
is de-pressurized
b. With the valve in open position (see valve position diagram on page 4), loosen all the
nuts on the body bolting. Remove all the bolts except one. Swing the body outside
the pipe.
c. Turn the handle to the half open position to assist in the removal of the seats
d. Replace with a new set of seats and body gaskets
e. Swing the body back into position. Replace the removed bolts, and tighten the bolts
according the valve assembly torque table on page 6
8.4. Replacing Stem Sealing Components
a. Follow the direction for replacing the seats and joint gaskets from a. to c.
b. To assist in loosening of the disc plate, place a rod of diameter smaller than the ball
orifice into the ball orifice. Loosen and remove the disc plate with two-prone tool.
Remove the set of Belleville washers and the gland. Place all removed parts in a
clean and secure place
c. Remove the rod. Turn the valve to the closed position (see valve position diagram
on page 4). Remove the seats and body gaskets. The ball should slide out with a
gentle push. Place all removed parts in a clean and secure place
d. Push the stem downward. It should come out through the center body. Remove the
stem then remove the pyramidal stem seal. Thoroughly clean the stem. Replace
with a new pyramidal stem seal.
e. Remove the v-ring stem packing from the center body cavity. Thoroughly clean the
center body. Replace with a new v-ring stem packing.
f. Replace the stem, the Belleville washers and the gland. Replace the disc plate. To
tighten the disc plate, hold the stem in place and tighten the disc plate with two-prone
tool. Refer to the stem disc torque in the valve assembly torque table on page 6 for
the correct torque value.
g. Turn the valve to the closed position (see valve position diagram on page 4)..
Replace the ball. Turn the valve to the open position. Replace the seats and joint
gaskets.
h. Swing the center body back into position. Replace the removed bolts and nuts.
Tighten the nuts according to valve assembly torque table on page 6.
