Document: Maintenance instruction
Product: XV
Issue: 2
Issue date: 2010-10-05
6
box. The joint of the second and third braid must be placed on the opposite long side of the
joint of the previous braid, not on top of each other.
12. Place the gland (8) on the stud bolts (8a).
13. Add the washers (8b) and nuts (8c).
14. Make sure the gate is completely closed
15. Install the retainer rings (12) and the seat sets (13) together with the o-rings (19). The pro-
cedure is described in A –Change of seat.
16. Put pressure on the gland (8) by tightening the nuts (8c) gradually and crosswise, see figure
4. The box packing must be equally compressed all around. Recommended torque for
gland nuts, see chapter D.
17. The gland (8) must put a uniform pressure on the box packing (9). The gland (8) must also
be in line with the gate (6) with the same distance between the gland and the gate all
around. Check that there is no metal contact between the gland (8) and the gate (6).
18. Install the other components in reversed order, step 2.
19. Make sure that the valve is closed.
20. Function test of the knife gate valve.
21. Install the valve in the system according to the operating instruction.
22. Operate the valve a few times before the system is pressurised.
Note:
The box packing may start to leak when the system is pressurised and the temperature in-
creases. This is caused due to that the box packing, which is a soft material, moves depending
on pressure and temperature and when the valve is operated. If the box packing is leaking,
tighten the gland nuts (8c) gradually and crosswise according to chapter D.
C –Change of box packing when the valve is installed in a system
No work is allowed on the Stafsjö knife gate valve when the system is pressurised or the
automatic actuator is connected. The system must be empty and free from pressure be-
fore any work begins and the actuator and accessories must be disconnected.
Work on the knife gate valve when the system is under pressure can cause damages on
persons and equipment.
Check that the system is free from pressure by:
oObserving the pressure measurement on the system
oOpening the drain on the pipe
When the system is free from pressure and empty:
1. Before starting the procedure open the valve and check the gate (6) visually for damages
such as dents and scratches. If the gate is damaged it can wear out the box packing (9) and
the seats (13), which could cause leakage. Stafsjö recommends changing the gate if it is
damaged to ensure the function of the valve. The procedure of changing the gate is de-
scribed in B –Change of gate and box packing.
2. Close the valve.
3. Loosen the nuts (8c) on the gland (8).
4. Lift the gland (8) and connect it to the stem nut (4) or gate clevis (17) with a wire to be able
to reach into the box packing (9).
5. Remove the box packing braids (9).
6. Clean the box from residues.
