8
1 T 70 en
4.6
Dismantling the valve
❑
Remove the valve from the pipeline.
❑
Remove the actuator as explained in 4.4.
❑
Loosen the gland nuts. Do not remove the gland.
❑
Remove the bonnet gland nuts and lift off the
bonnet. If necessary use an extractor to grip the
gland. See Fig. 11.
❑
Install the locking tools (see Fig 12) to push sup-
port seat rings or bellows in to back position.
❑
Pull out the ball and seats with the ball in the
'Open' position. See Fig. 13. Lower the ball on a
soft surface.
❑
To check the bearings, remove the circlips if any
(27) and pull the bearing bushing (5) out off the
shaft.
❑
Pull out the seat support rings or bellows.
4.7
Checking the parts of a dismantled
valve
4.7.1
Seats
Seat T
❑
Check the sealing and back surfaces of the seat
ring (7), the support ring (35) and the o-ring (63).
Sealing surfaces may require lapping.
❑
If damage is extensive, the parts should be
replaced. Check the spring groove for any impu-
rities which may jam the support ring (35).
Seat S
❑
Check the sealing and back surfaces of the seat
ring (7), the support ring (35) and the o-ring (63).
Sealing surfaces may require lapping. The seal-
ing surface of the seat (7) is lapped against ball
surface.
❑
If damage is extensive, the parts should be
replaced. Check the spring groove for any impu-
rities which may jam the support ring (35).
Fig. 11
Lifting the bonnet
Fig. 12
Spreading and locking tool
Fig. 13
Pulling out the ball
Fig. 14
Seat T
Fig. 15
Seat S
62
63
35
7
64
7
35
64
63
62
