12-4
Troubleshooting Guardian Metal Bellows Seals
Failure
Probable Cause
Corrective Action
Leakage through
1. Insufficient compression of
1. Tighten bonnet flange bolting until
bonnet or sleeve
bonnet flange
leakage stops
gaskets
2. Worn or defective bonnet, sleeve or
2. Disassemble and replace all gaskets,
seat ring gasket
including seat ring gasket
Leakage through
1. Failure of metal bellows
1. Disassemble and replace metal bellows
packing box or
seal assembly
seal assembly and all gaskets
“tell-tale” tap
Valve does not
1. Improper actuator stem engagement
1. Correct stem engagement (refer to step 10
seat or seats
in the “Reassembly” section)
too early
GUARDIAN II METAL BELLOWS SEAL
Disassembling the Guardian II Metal
Bellows Seal
To disassemble the Guardian II metal bellows seal
valve, refer to Figures 2 and 3 and proceed as follows:
WARNING: Depressurize line to atmospheric pres-
sure, drain all process fluids and decontaminate
the valve (if toxic or hazardous materials are
present). Special attention should be given to the
housing packing area and inside the bellows hous-
ing and when disassembling the plug head. Failure
to do so can cause serious injury.
1. Loosen the actuator stem clamp.
2. Remove the packing box bolting.
3. Remove the yoke clamps.
4. Remove the actuator by turning it completely off
the bellows seal stem and bellows seal housing.
CAUTION: Although the valve incorporates an
anti-rotation pin, care should be taken not to
put excessive torque on the plug stem/bellows
assembly. Excessive torque can damage bel-
lows and/or shear the anti-rotation pin. Flats
on plug stem should only be used to prevent
stem from rotating while removing actutator or
installing plug heads.
CAUTION: Heavy actuators may require a hoist.
A lifting ring is provided on most actuators for
this purpose; otherwise, lift by the yoke legs
using lifting straps and the hoist.
5. Remove the bonnet flange bolts or nuts.
6. Remove entire bellows seal assembly, plus the
bonnet and plug, by lifting them straight out of body.
WARNING: If there has been a bellows failure,
process fluid may be trapped in the bellows
seal housing; therefore, be extremely cautious
when disassembling the valve and bellows
assembly.
7. Disassemble the bellows assembly by first remov-
ing the plug head. Begin by grinding the tack welds
off where the plug head meets the plug stem. Next,
securely hold the plug stem by the flats, being
careful not to damage the threads or gall the shaft.
Using a wrench on the plug head flats, turn the plug
head off the stem.
8. Remove the metal bellows assembly by carefully
pulling it out of the housing.
9. Pull the stem guide housing off the bellows assem-
bly. Jack screw holes are provided, if needed.
10. Remove the bellows housing gasket from the bel-
lows housing.
11. Inspect lower stem guide for galling or wear. If
replacement is required, use a dowel and arbor to
press out the soft guide and guide retainer in the
case of soft guides. When hard guides are used,
the entire guide will be pressed out in one piece.
12. Remove the seat ring, seat retainer, seat ring
gasket, and bonnet gasket from the body. Refer to
Maintenance Instructions 1 for further details.
Reassembling the Guardian II Metal
Bellows Seal
To reassemble the Guardian II metal bellows seal
valve, refer to Figures 2 and 3 and proceed as follows:
1. If bellows failure has been determined, properly
discard the old assembly and obtain a new one.
Inspect all parts for wear and replace. All gaskets
must be replaced.
2. Replace the lower stem guide into the stem guide
housing. With soft guides, insert the Teflon
®
liner
into the guide retainer and then press this assem-
bly into the guide housing. With hard guides, press
the solid guide into the guide housing. (An arbor is
required to press in these parts.)
3. Install the stem guide housing over the stem and
into the lower flange of bellows assembly. Jack
screw threads should be facing outward.
