EB 8097 EN 9-5
Servicing
1. Unscrew the nuts (9 and 10) from the
plug stem (2).
2. Depending on the version, unscrew and
remove the clamp (34) or bolts (32). Re-
move the yoke (1) together with plug (2)
and, if installed, centering ring (25) in-
cluding sealing parts.
Possible sealing parts:
− PTFE seal: stem seal (3)
− PEEK seal: stem seal (3), centering
ring (25) and O-ring seal (26)
− Anti-crystallizing seal: metal center-
ing ring (25) with seal (23) and
O-ring seal (26)
3. Pull the plug (2) out of the yoke (1).
Make sure that the stem seal (3) is not
damaged.
4. Use a suitable tool to force out damaged
parts, e.g. bearing bushing/wiper seal
(24) and stem seal (3).
In version with steam barrier, also re-
move packing (21), washer (17), spring
(13) and, if installed, spacer (18 or 41).
Clean the packing chamber.
5. Check the surface of the plug stem (2) to
ensure it is free of score marks and still
has a mirror nish. If the surface has
aws, polish it again to ensure the stem
seal (3) cannot get damaged.
6. Apply a suitable lubricant to the new
parts and plug stem (2).
7. Place the stem seal (3) initially in the op-
posite direction with the lip facing to-
ward the thread end over the plug stem
(2) to stretch the lip of the stem seal
slightly.
8. Carefully pull the stem seal (3) off again.
9. Push the new centering ring (25) with
sealing parts (depending on version)
over the plug stem (2).
10. Carefully slide the stem seal (3), center-
ing it, over the thread end of the plug
stem (2). The stem seal must t tightly,
but slide easily over the plug stem.
11. Insert the plug stem (2) with stem seal (3)
and centering ring (25) into the yoke (1).
12. Push the bearing bushing/wiper seal
(24) over the plug stem (2) into the yoke
(1).
13. Carefully place the yoke (1) onto the
valve body (4).
14. Apply a suitable lubricant to the clamp
(34) and the anges of the yoke (1) and
valve body (4).
15. Depending on the version, position
clamp (34) and tighten the clamp screws
or insert bolts (32) on the yoke (1) and
tighten in a crisscross pattern. Observe
tightening torques.
16. Versionwithclamp: hit the clamp (34)
lightly with a plastic hammer and tighten
the clamp screw again.
Repeat this procedure several times until
all parts t properly to achieve a leak-
tight body.
If the weight of the bonnet (1) in the ver-
sion with steam barrier is too light to put
the clamp back on, slightly compress the
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