2 BW 70 en
17
Now the following parts can be changed with the recom-
mended spare part sets:
8.
All parts must be cleaned accurately before reassembly.
9.
Check the shafts for wear. It is recommended to replace
the shafts if any grooves or other damage is found.
10. The reassembly takes place in reverse order. To avoid
damage to the seals, install the bearing bushings (420,
424, 425) with extreme care.
11. Tighten the cover screws (103, 432) using a suitable
torque wrench for the given torques, in compliance
with Section 10.8.
12. Check the high performance disc valve for its tightness
before reinstallation. The instructions for installation
can be found in Section 3.3 Installation.
10.7
Replacing the gland packing
Pre-compressed graphite rings are used as a standard gland
packing. The packing construction is live loaded as stan-
dard.
The graphite packing (451) shall be changed if leakage
occurs even after the hexagon nuts (494) have been tight-
ened as recommended.
□
Make sure the valve is not pressurized.
□
Unfasten the nuts (494) and remove the washer (456),
the spring washer (476), the disc springs (457), the
sleeve (436), the gland (491) and the compression ring
(492).
□
Remove old packing rings (451). Do not damage the sur-
face of the packing ring counterbore and shaft. It is not
necessary to change the anti-extrusion ring (452).
□
Clean the gland and packing ring counterbore. Install
new set of graphite packing. Slip the rings onto the
shaft. Ensure that there are no burrs in the keyway
groove which could damage the packing. Position the
cut ends of the graphite rings at 90° angle to each other.
□
Mount the compression ring.
□
Install the gland.
□
Put the sleeves on the studs.
□
Mount the disc springs according Figure 34.
□
Put the spring washers on top.
□
Add the washers.
□
Place the nuts on the washer.
□
Compress the gland packing by tightening the nuts
crosswise with a torque wrench until the disc springs
have a value of compression (h1- h2) as in Table 5.
□
Carry out 3-5 operation cycles with the valve. Suitable
range of movement is about 80 %. It is not necessary to
fully close or open the valve during operation.
□
Re-tighten the nuts with a torque wrench until the disc
springs have a value of compression (h1- h2) as in Table
5 if necessary.
If leakage still occurs when the valve is pressurized, re-
tighten the nuts but do not exceed the value of compres-
sion (h1- h2) in Table 5 by 50 % or do not fully compress the
disc springs.
Fig. 34
Gland packing
Table 4
Spare part sets
Quantity
/ Valve
Description
Contents
1x
Set 1 (Soft parts)
Pos.107, 451, 470
1x
Set 2 (Sealing)
Pos. 321, 404, 424, 425, 447, 456, 457
304, 420, 452, 476
1x
Set 3 (Heavy overhaul)
Pos. 201, 401, 402
301, 303, 310, 491, 440, 462, 492
CAUTION:
Do not dismantle the valve or remove it from the pipe-
line while the valve is pressurized!!
gland (491)
anti-extrusion ring (452)
graphite packing (451)
disc spring (457)
sleeve (436)
spring washer (476)
washer (456)
nut (494)
stud (496)
compression ring (492)
n = amount of disc springs in spring set
i = amount of disc springs in spring stack
for all valves:
n = 3
i = 4
h2
Ø d
h1
