H. Re-Machining Nozzle Seats
1. Remove the nozzle from the valve to be
remachined. If it cannot be removed from the
base, re-machine it inside the base.
2. Take the following steps to setup the lathe and
nozzle:
a. Grip the nozzle in a four-jaw independent chuck
(or collet, if appropriate), using a piece of soft
material such as copper or fiber between the
jaws and the nozzle as shown at A (Figure 32).
b. True up the nozzle so that the surfaces marked
B and C run true within .001” (0.03 mm) on
indicator (Figure 32).
3. Take the following steps to re-machine the
metal-to-metal nozzle (Figure 27a and Table 2):
a. Make light cuts across the surface L at 5º until
the damaged areas are removed. Turn to the
smoothest possible finish.
b. The nozzle is now ready for lapping.
c. When the minimum dimension H is reached,
discard the nozzle.
4. Take the following steps to re-machine the O-Ring
seat seal (Figure 27b and Table 2):
a. Make light cuts across surface A (45º) until
the damaged areas are removed. Turn to the
smoothest possible finish.
b. Re-machine radius R.
c. The nozzle is now ready for lapping.
d. When the minimum dimension H is reached,
discard the nozzle.
I. Re-Machining the Disc Seat
Take the following steps to machine the standard disc
seating surface (Figure 33):
1. Grip the disc in a four-jaw independent chuck (or
collet, if appropriate), using a piece of soft material
such as copper or fiber between the jaws and the
disc as shown at A.
2. True up the disc so that the surface marked B and C
run true within .001” (0.03 mm), TIR.
3. Make light cuts across the seating surface L until
damaged areas are removed. Turn to the smoothest
possible finish.
4. The disc is now ready for lapping.
5. Discard the disc if the minimum dimension N or T
(Figure 34, Table 5) is reached. Do not reestablish
surface C.
ATTENTION!
Do not remachine a Thermodisc or O-Ring Retainer.
Figure 32: Nozzle Positioned in a Jaw
C
90°
L
B
Disc
Chuck Jaw
A
Figure 33: Standard Disc Seating Surface
XIV. Maintenance Instructions (Contd.)
40 | BHGE
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