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XIV. Maintenance Instructions
A. General Maintenance
Information
After the valve has been disassembled, a close inspection
should be made of the seating surfaces. In a majority of
cases, a simple lapping of seats is all that is necessary to put
the valve in first class working order. If an inspection of the
parts shows the valve seating surfaces to be badly damaged,
machining will be required before lapping. O-Ring seat seal
valve nozzles can only be reconditioned by machining, not
lapping. (For specific information concerning the machining
of nozzle and disc seating surfaces, see Paragraphs F and G
which follow.)
The seating surfaces of the metal seated Consolidated Safety
Relief Valve are flat. The nozzle seat is relieved by a 5° angle
on the outside of the flat seat. The disc seat is wider than the
nozzle seat; thus, the control of seat width is the nozzle seat
(see Figure 18).
Reconditioning of the seating surfaces of the nozzle and disc
is accomplished by lapping with a cast iron lap, and lapping
compound.
ATTENTION!!
Figure 18a: Metal Seat Nozzle
5°
45°
30 | BHGE
C
B
D
Nozzle
Bore
Figure 18: Main Valve Nozzle Critical Dimensions
In order to establish leak free valve seats, the nozzle seating
surface and the disc seating surface must be lapped flat.
B. O-Ring Seat
The nozzle must not have any defects to prohibit the O-Ring
from sealing properly, especially the OD of the seat where the
surface must maintain a minimum of 32 RMS finish. See Figure
18 and Table 2 for reworking O-Ring Nozzle.
The O-Ring Retainer must also maintain a flat surface for it
to sit on the Nozzle. Only polishing of surface can be done
since material removal from this surface will cause the Nozzle
to over engage O-Ring. Polishing paper or some other light
abrasive can only be used since the part cannot function
properly if its overall dimensions are changed significantly.
If significant corrosion or damage has occurred on O-Ring
retainer, discard and replace.
C. Lapping Nozzle Seats
(Metal Seat - Non-O-Ring Styles)
Lap the 5º angle of the nozzle first (Figure 19, View A). Then,
invert the nozzle lap and use the flat side as a "starter" lap to
ensure the seat is square. Use a ring lap in a circular motion
to finish lapping and reconditioning of laps. Keep the lap
Figure 18b: Soft Seat Nozzle
F
45°
© 2019 Baker Hughes, a GE company. All Rights Reserved.
C
B
D
Nozzle
Bore
F
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