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XVIII. Part Inspection of Pilot Valve
After the valve has been disassembled, all parts should be
given a visual inspection. Some key areas to check with the
boundaries for reworking parts are listed blow.
A. 39PV07/37
1.
Main Piston: Galling or excessive wear on the small
diameter end where it engages the spring seals or on the
spherical bearing surface. Any corrosion or pitting that
appears detrimental to the function of the valve. The part
can be polished as long as the outside diameter of the
stem remains at .243 ± .001" (6.18 ± 0.03 mm). The stem
itself must have a T.I.R of .001" (0.03 mm) along its length.
The upper diameter where the Spring Seal (Main Piston)
rides must be 1.495 ± .001 (37.97 ± 0.03 mm) on 39PV07
model or .970 ± .001" (24.64 ± 0.03 mm) on 39PV37. A
surface finish of 8 RMS must be maintained for proper
sealing on these surfaces.
2.
Insert Top: Galling or excessive wear on the inside
diameter that guides the Main Piston. Check for any
corrosion or pitting. Also, check for galling of threads.
3.
Insert Bottom: Galling or excessive wear on the inside
diameter that guides the Main Piston. Check for any
corrosion or pitting.
4.
Adjuster Top: Galling or excessive wear on the inside
diameter that guides the Main Piston. Check for any
corrosion or pitting. Also, check for galling of threads.
5.
Adjuster Bottom: Galling or excessive wear on the inside
diameter that guides the Main Piston. Check for any
corrosion or pitting. Also, check for galling of threads.
46 | BHGE
6.
Top Plate: Galling or excessive wear on the inside
diameter that guides the Main Piston. Check for any
corrosion or pitting. Also, check for galling of threads.
7.
Bonnet: Check for any corrosion or pitting. Also, check for
galling of threads for the compression screw and where it
attaches to the Pilot Base.
8.
Compression Screw: Galling at the spherical bearing
surface or in the thread. Check for any corrosion or
pitting.
9.
Spring Washer(s): Galling at the spherical bearing surface.
Check for any corrosion or pitting.
10. Pilot Base: Check for any corrosion or pitting. Also, check
for galling of threads.
11. Spring: Check for any corrosion or pitting.
If any damage listed above is present, the part should be
replaced or repaired per instruction. Other valve parts may
be acceptable with light corrosion, pitting, or minor damage
of other types if it can be determined that it will not affect
product performance. All O-Rings and spring seals should be
replaced each time the valve is disassembled.
Refer to Tables 22 and 23 for O-Ring/Spring Seal repair kits.
Recommended spare parts are listed in Table 20.
© 2019 Baker Hughes, a GE company. All Rights Reserved.
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