1 D 71 en
7
4.5
Dismantling the valve
❑
Place the valve on its flange on a clean, level sur-
face made of wood, hardboard or plastic. If nec-
essary, support the actuator so that it cannot
overturn as the mounting bolts are being
removed.
❑
Remove the actuator if it is still attached to the
valve.
❑
Remove the mounting brackets of the valve.
❑
Tap loose the key at the end of the ball stem.
❑
Remove any burrs from the keyway edges.
❑
Loosen the gland packing nuts and the bonnet’s
fastening bolts and pull the bonnet away from the
ball stem.
❑
Remove the bolts keeping the body halves
together and lift the upper body half on its flange.
4.6
Removing and inspecting the valve
parts
4.6.1
Ball
To make carrying and inspection easier, the balls
>DN300 (12") have a threaded hole at the end of the
stem for an eyebolt.
❑
Lift the ball from the body on a soft surface and
clean it.
❑
Check the sealing and bearing surfaces of the
ball stem.
❑
Remove any minor scratches and impurities
using an emery cloth.
❑
File off any burrs from the stem keyway.
❑
If the ball has deep scratches on its sealing and
bearing surfaces or if it is not fully spherical, it
should be sent to the manufacturer for repairs.
4.6.2
Bearings
❑
Check the bearings. In PTFE bearings, the stain-
less steel net should not be visible.
4.6.3
Seats
❑
Turn the body upside down and detach the seat
by tapping at it through the flow opening with a
rubber or plastic mallet.
❑
Clean and check the tightening surfaces.
4.6.4
Body and bonnet
❑
Always replace the body and bonnet gaskets
during maintenance.
❑
Remove existing gaskets from all sealing sur-
faces and clean the surfaces carefully.
❑
Do not round the sharp edges at the conver-
gence point of the body joint and bonnet sealing
surfaces, as this could cause leaks. See
Figure 8.
❑
Remove the gasket from the bonnet, for example
with a screwdriver.
4.6.5
Other parts
❑
Clean all parts carefully, including the studs and
nuts.
❑
After cleaning and checking all parts, keep them
in a protected place until reassembly. Handle the
ball, its seats and the body joint surfaces with
particular care.
❑
If necessary, send the valve to the manufacturer
for repairs.
4.7
Reassembling the valve
❑
Reassemble the valve by placing the female
body half on a level surface in an upright position
with the body joint pointing upwards.
❑
Then put the parts in their place in the following
order:
1.
Seats
2.
Ball with its bearings
3.
Body joint between body halves and bonnet
4.
Gland packing
4.7.1
Fitting the seats
T and S seats
❑
Check the sealing surfaces.
❑
Place the back seals (63) into their position to the
body grooves. See Figure 9.
❑
Place the back-up rings (64) made of PTFE strips at
the side of the O-ring. To ensure that the seam
becomes flexible, the strip must have slanted ends.
❑
For easier assembly, lubricate the O-ring and
back-up ring surfaces facing the seats with sili-
cone grease or another suitable substance.
❑
Place the spring (62) into the groove in the seat
(7). Connect the ends of the spring.
❑
Place the seats into the body by hand or if nec-
essary, using a plastic mallet. The seat is in cor-
rect position when the spring touches the body
shoulder.
Fig. 8
Sealing surfaces
The edges must remain sharp
