Curtiss-Wright 2600 Series, Maintenance Manual

Page: 13 / 48

13
6. Disassembly Instructions
General Disassembly of Valves
After the valve is received and checked it is ready for shop inspection and
repair. The valve should be carefully dismantled. If you are unfamiliar with
this line of Farris valves carefully study the cross-sectional drawings in
Figures 4.1 through 4.5 to familiarize yourself with part terminology and
location. Proper facilities should be available for segregating parts as the
valve is dismantled. At each stage in the dismantling process, all parts of
the valve should be visually inspected for evidence of wear and corrosion.
If parts are worn, replace them. See Appendix G for necessary tools.
The following general points will provide a brief checklist to follow during
disassembly. Detailed discussion will follow for specific critical parts.
Check for the presence of wire seals at all
points of adjustment.
Check for complete and properly identified
nameplates and tags.
Check the condition of flanges; look for
evidence of pitting, roughening, deterioration
of gasket surface, distortion, etc.
Visually inspect springs for evidence of
corrosion, cracking, and correct selection.
Visually inspect bellows (if the valve is of
bellows type).
Examine o-ring condition (if applicable).
Visually inspect inlet and outlet openings; look for evidence of deposits
of foreign material and for corrosion. Note the condition of external
surfaces and look for any indication of corrosion or evidence of
mechanical damage.
Check and note the body, nozzle and bonnet wall thickness, thread
and stud condition.
Verify valve components and material and check against
nameplate information.
Disassembly Instructions:
Farris 2600 Series valves should be disassembled
as described below. Parts identification may be
found in Figure 4.1 on page 8. The parts from
each valve should be properly marked and
segregated to keep them separate from parts
used in other valves.
1. Cut the wire seals and remove the
Cap
[3] and
Cap Gasket
[21]. For valves equipped with a
lifting lever, follow the instructions in Appendix D.
(Figure 6.1)
2. Before loosening the Jam Nut [11], measure the location of the Spring
Adjusting Screw (SAS) [10] by marking the SAS [10] above the Jam
Nut [11]; or by counting the number of counter clockwise revolutions of
the SAS [10] until the Spring [20] is no longer compressed. This will
allow the approximate set pressure to be re-established when
reassembling the valve.
(Figure 6.2)
3. Remove the
Jam Nut
[11] and
SAS
[10].
Figure 6.2
Stem
Jam Nut
Bonnet
Spring
Adjusting
Screw
Mark with
Paint or
Marker
Measure
Figure 6.1
Be aware that process
fluids may be trapped inside
the cap and bonnet. Use
appropriate PPE as required.
WARNING
A PRV is under spring load.
Ensure disassembly
procedures are followed
carefully to avoid serious
injury or death.
DANGER