| Generally
JVS Mud Valves are in-line repairable and all routine
maintenance such as gland packing change out, seat replacement,
gate and spindle replacement can be performed in online
condition. |
| 1.
|
If
the valve is to be dismantled in the flow line
ensure all pressure has been dissipated from the
Flow line. Isolate the valve by closing and locking
/ Chaining valves upstream and downstream of the
subject valve and label them “CAUTION
DO NOT USE” |
| 2. |
Run
the valve to the fully open position. Remove hand
wheel nut & hand wheel |
| 3. |
Remove
the body bonnet nuts (4 nos.) and withdraw the
bonnet assembly along with the gate engaged in
the tee slot of the stem from the body. |
| 4. |
Remove
the seat from the body by pulling the pins together
to collapse the seat & at the same time pulling
the seat up out of the body. |
| |
NOTE
: At this point the gate and seat may
be replaced with no further dismantling of the
Valve, If these are the only parts that need to
be replaced. |
| 5. |
Turn
the stem clockwise (left hand thread) to remove
it from the underside of the bonnet |
| |
Remove the Yoke nuts to remove the
yoke. |
| 7. |
Remove
in the following order: retainer bush, stem seal,
gland bush and gland packing. |
| 8. |
Unscrew Yoke sleeve from
Yoke clockwise (right hand thread) |
|
De-grease
all parts to allow close inspection of the sealing surfaces.
Close inspection should be carried out on the following
areas :- |
|
Gate and
seat sealing surfaces for wear or damage. |
| |
Stem threads
for wear or damage. |
|
Mud cut inside body
portion. (In this case in-situ repair is not possible) |
|
ALL
‘O’ RINGS ARE TO BE REPLACED COMPULSARILY
REGARDLESS OF ‘O’ RING CONDITION. |
|
| 1.
|
Before
starting the assembly ensures every part is
clean and free from foreign matter. Pay close
attention to the stem thread surface that passes
through the stem packing & Polish the same
if required with a fine grade emery paper. |
| 2. |
Apply
a coat of grease to ‘O’ ring seat
and stem. |
| 3. |
Pass
the threaded section of the stem up through
the bonnet. |
| 4. |
4.
Pass the Gland packing over the end of the stem
and into the seal pocket in the bonnet. |
| 5. |
Place
the gland bush over the stem. Put the retainer
bush and stem seal above it. |
| |
Screw the
yoke sleeve into the yoke up to mid point if
the threaded length. Place the yoke down over
the thread on the stem and on to the bonnet.
Secure the yoke to the bonnet. |
| 7. |
Turn
the yoke sleeve clockwise (right hand thread)
until it bottoms out on the retainer bush, turn
back approximately 1/8th of a turn. Place the
tee slot of the gate come into contact with
the lugs on the bonnet. Turn the gate to line
up with the slot in the bonnet and retract the
gate by turning the yoke sleeve anti clockwise
(right hand thread). Replace the hand wheel
and screw the hand wheel nut. |
| 8. |
Place
the seat on a suitable flat surface. Put the
bonnet assembly on top of the seat so that the
pins on the seat locate in the holes at the
underside of the bonnet. Turn the hand wheel
clockwise until it comes into contact with the
yoke, the pins should still be located at the
bottom of the underside of the bonnet, if the
bonnet assembly rises off during this operation
if would indicate that the gate was to far out
of the bonnet. (refer step 9). Make a pencil
mark on the gate in line with the bottom of
the seat bore. Turn the hand wheel anticlockwise
to raise the gate back up into the bore. Measure
the distance between the pencil mark and the
bottom of the gate, this should be in range
of 9.5 mm – 12.5 mm. |
| 9. |
If
the distance measured in step 8 is correct,
continue to step 10. If adjustment is required
remove the seat & hand wheel. Turn the yoke
sleeve clockwise so that it touches the retainer
bush and adjust as below.
Hold the yoke sleeve & turn the gate, stem
together anti-clockwise to reduce the distance
given above is achieved. |
| 10. |
Replace
the bonnet ‘O’ ring into the ‘O’
ring groove in the body. Locate the bonnet /
seat assembly over the body-bonnet studs, ensuring
that the seat slides smoothly into the body.
Tighten with body bonnet nuts. |
|
