Richter NKP Series Butterfly Valves - Manual (Page 13)

Series NKL, NKLP, NKS, NKSP, NK, NKP
Page 13
9520-070-en Revision 04
TM 7113 Edition 05/2008
8 Malfunctions
Flange connection ball valve/pipe is leaking
Retighten the flange screws to a tightening torque
according to Section 1.3. If this does not remedy
the leak, the recommended torques may be ex-
ceeded by 10%.
If this also fails to stop the leak, dismantle and in-
spect the ball valve.
Dismount and inspect the valve.
Stem passage leaking
With no safety stuffing box:
Dismount valve and repair.
With safety stuffing box:
First of all, the packing gland follower can be tigh-
tened. For torques see Section 1.3.
Then dismount the valve as quickly as possible
and repair.
Medium leaking at the partition between lower and
upper halves
Dismont valve and repair, probably the stem seal
is not tight.
Valve does not switch
Has the locking plate been dismounted?
See Section 5.4.
Is the actuator supplied with power?
Has a directional control valve been correctly con-
nected?
Is there foreign matter in the valve?
The bore of the valve is leaking
Wear at the valve actuation ?
Do limit stops have to be adjusted?
Is the shaft deformed?
Deformation, damage or wear to body lining or
disc?
9 Maintenance
All repair work is to be performed by qualified per-
sonnel using the appropriate tools.
For the arrangement, designation and item num-
bers of all parts of the valve, see Section 10.
Spare parts are to be ordered with all the details in
acc. with the valve identification.
Only original spare parts may be installed.
To prevent leaks, a regular check of the connecti-
on screws should be made in line with the opera-
ting requirements.
For torques see Section 1.3.
When disassembling and assembling the valve,
attention is to be paid to the tables and drawings in
Section 1 and 10.
As the body lining 409 is drawn over the disc/stem
unit 221 while warm, this work should only be car-
ried out by the manufacturer.
Has the pump been shut down, drained and flus-
hed according to the regulations?
See also Section 7.3.
If assembled incorrectly, individual compo-
nents of the valve may be damaged and this
can result in malfunctions during operation.
9.1 Notes for assembly
The flexible inlay 521 expands during assembly.
Do not cut off the overhang, but push back into the
lower and upper part of the shell 120.
Before tightening the body screws 914/1 (on
NKL/NKLP threaded rod 918/1 and hex. nut
920/2), align the disc/stem unit 221 centrally in the
closed position.
Mark the position of the disc/stem unit 221 against
body lining 409 at the hub, so permitting switching
only to this point during later test switching.
With disc/stem unit in closed position, tighten the
body screws (914/1, as well 918/1 and 929/2) until
the gap between the upper and lower part of the
shell 120 is ca. 5 mm.
Open the valve several times counterclockwise
(when viewing the stem unit) and close again in
the opposite direction. A sealing edge can form in
this way.
Never switch in the other direction of
rotation over the sealing edge!
Tighten the body bolts 1-2 mm when disc in closed
position.
Repeat the previously described process once or
twice.
When finally tightening the body bolts, pay attenti-
on to the torques provided in Section 1.3.