Document
Document id
Issue Date
Maintenance instruction
mi-WB14E-HW-SC-EN 1
2021-04-14
5 (10)
Before assembling make sure you have:
1.
Seat (13)
2.
Two short pins if the valve is DN 350/14” or larger (13b).
3.
TwinPack box packing braids in correct dimension and length (9).
4.
Box bottom scraper/s (9a) and optional top scraper/s (9b).
5.
Guiding pads (14).
6.
Locking nuts (8c) and washers (8b). Stud bolts (8a) if necessary.
Additional equipment
•
Synthetic lubricator (Multipurpose Grease OKS 1110 or similar grease approved for EPDM, Nitril and
FEPM)
•
A plastic surfaced hammer and/or a pneumatic cylinder to push down the gate in closed position.
•
Necessary lifting equipment for valves > DN 350/14”.
•
Adhesive paste type Terason or equal and clamps to valves > DN 350/14”.
Before assembling starts, check the valve body (10) and gate (6) don’t have any damages such
as dents and scrapes. If the gate is damaged it can wear out the box packing (9) and seat (13)
very fast resulting in leakage. To ensure optimal operation, Stafsjö recommends changing the
gate if it is damaged and invest in a new knife gate valve if the body is damaged.
Up to DN 300/12”, follow steps below to change box packing, scrapers, seat and guiding pads.
1.
Make sure that the valve body gate groove is clean and free from grease and residues.
2.
Put the valve in a vertically up-right position in a screw vise.
3.
Mount the seat (13) by pressing it all the way down into the bottom of the valve body until the seat is
even with the valve bore. It is important that the seat is symmetrical mounted and sticks out equally at
both sides on top of the valve body.
4.
Apply grease (Multipurpose Grease OKS 1110 or similar grease approved for EPDM, Nitril and FEPM) on
the gate edges to decrease friction against the seat.
5.
Push down the gate (6) to the bottom (100 % closed position) of the valve body (10) by using your own
weight or use a plastic hammer.
6.
Control the gate (6) is centered in the valve body (10).
7.
Install guiding pads (14) in the slots in between the gate and valve body. Ensure you install the guiding
pads correctly
a.
Radius should be downwards against the bore side.
b.
Bevel edge should face the valve body, not the gate side.
8.
Install the first layer of TwinPack box packing braids (9) on each side of the
gate. Make sure they close tightly against the seat. NOTE! Do not use any
sharp tools when installing the box packing braids. It can damage the box
packing and the gate!
9.
Add box bottom scrapers (9a) on top of the first layer of braids on each
side of the gate. Box bottom scrapers are a bit thicker than optional top
scrapers. Ensure you install correct ones.
10.
Add another two layers of braids (9) on each side of the gate on top the scrapers (9a).
11.
Optional top scrapers (9b) can be added on top of the final third layers of braids.
12.
Install the gland (8) and tighten it with washers (8b) and locking nuts (8c) gradually and crosswise
according torques submitted in table below. Make sure that the gland is centered in the box and has an
equal distance from the gate all around. Ensure there is no metal contact in between gate and gland.
Recommended maximum torque for gland nuts
DN
Nm
lbf x ft
50-80
20
15
100-150
25
18
200-300
30
22
Box packing
Optional top scraper
TwinPack braids
TwinPack braids
Bottom scrapers
TwinPack braids
3
1
2
4
