XVIII. Part Inspection of Pilot Valve (Cont.)
12.
Modulator Stop:
Top seating surface for cuts
or deformities. The surface can be lapped if the
distance from the seat to the outside shoulder does
not reduce to less than .086” (2.18 mm).
13.
O-Ring Retainer:
Seating surface for cuts or
deformities. The surface can be lapped if the
overall height of the part does not reduce to less
than .160” (4.06 mm). Also, check the outside
diameter for any scratches that might prevent the
O-Ring (Modulator Seat) from sealing.
14.
Modulator Piston Bottom:
Galling or excessive
wear on the outside diameter that rubs against the
Modulator Base. Make sure that the lip holding
the O-Ring (Modulator Seat) is not deformed.
Also, check the outside diameter of the O-Ring
groove for scratches that might cause the O-Ring
(Modulator Seat) not to seal. Check for any
corrosion or pitting.
15.
Modulator Base:
Galling or excessive wear on any
inside diameter. Any corrosion or pitting.
C. 39MV22/72
1.
Main Piston:
Galling or excessive wear on the
diameter where the Spring Seal (Main Piston)
engages 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 where the
Spring Seal (Main Piston) rides must be .970 ±
.001” (24.64 ± 0.03 mm) on 39MV22 model or .812
± .001” (20.63 ± 0.03 mm) on 39MV72. A surface
finish of 8 RMS must be maintained for proper
sealing on these surfaces.
2.
Piston Nose:
Galling or excessive wear on the
diameter where the spring seals engage. 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” (6.17 ± 0.03 mm). The stem itself must
have a T.I.R of .001” (0.03 mm) along its length.
3.
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.
4.
Insert Bottom:
Galling or excessive wear on the
inside diameter that guides the Main Piston. Check
for any corrosion or pitting.
5.
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.
6.
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.
7.
Vent Seal Adaptor:
Check for any corrosion or
pitting.
8.
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.
9.
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.
10.
Compression Screw:
Galling at the spherical
bearing surface or in the thread. Check for any
corrosion or pitting.
11.
Spring Washer(s):
Galling at the spherical bearing
surface. Check for any corrosion or pitting.
12.
Pilot Base:
Check for any corrosion or pitting.
Also, check for galling of threads.
13.
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 27 and 28 for O-Ring/Spring Seal repair
kits. Recommended spare parts are listed in Table 25.
68 |
Baker Hughes
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