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Baker Hughes
© 2020 Baker Hughes Company. All rights reserved.
XXIII. Maintenance Tools and Supplies (Cont.)
C. Lapping Tools
The following tools are required for proper maintenance of
Pilot Operated Safety Relief Valve metal seats, and may
be purchased from Baker Hughes.
1. Ring Lap: The ring lap is used for lapping the disc seat
and finish lapping of the nozzle seat.
2. Lapping Plate: The lapping plate is used for
reconditioning the ring lap. It may also be used for
lapping the disc. One 11” (279.40 mm) diameter
plate is required for the entire line of valves (Part No.
0439004).
3. Lapping Compound: Lapping compound is used as
a cutting medium when lapping the valve seats, as
specified in Table 14.
4. Drift Pins: Two drift pins are required for the removal
of the disc from the disc holder. Refer to Figure 60 and
Table 15 for Drift Pin specifications.
5. Nozzle Lap: The nozzle lap is used for lapping the
nozzle seat and has one flat side and one side with
a 5° angle. This lap guides in the bore of the nozzle;
therefore, a different size lap is required for each valve
orifice (Table 16).
6. Lifting Tools: Lifting tools are used for the removal of
upper internal parts of larger valves, as specified in
Table 17.
Table 14: Lapping Compound Types
Brand Grade Grit
Lapping
Function
Size
Container
Part
No.
Clover
1A
320
General
4 oz
199-3
Clover
3A
500
Finishing
4 oz
199-4
Kwik-Ak-
Shun
-
1000 Polishing
1 lb
199-11
2 lb
199-12
Table 15: Drift Pin Types
Orifice
A
B
Part
No.
in.
mm
in.
mm
D, E, F, G, H, J, K 1.75 44.5 .219 5.55 430401
L, M, N, P
2.50 63.5 .375 9.53 430402
Q, R
3.00 76.2 .625 15.88 430403
T
3.50 88.9 .875 22.23 430404
Table 16: Nozzle Lap Dimensions
Orifice
Nozzle Bore
Nozzle
Lap
Nozzle
Lap
Handle
Ring
Lap
1
min.
max.
in
mm
in
mm
D
.404
10.26
.409
10.39
4451501
544603
1672805
E
.539
13.69
.544
13.82
4451502
544601
1672805
F
.674
17.12
.679
17.25
4451503
544601
1672805
G
.863
21.92
.868
22.05
4451504
544601
1672805
H
1.078
27.38
1.083
27.51
4451505
544601
1672805
J
1.380
35.05
1.385
35.18
4451506
544601
1672805
K
1.650
41.91
1.655
42.04
4451507
544601
1672807
M
2.309
58.65
2.314
58.78
4451602
544601
1672809
N
2.535
64.39
2.540
64.52
4451603
544601
1672809
P
3.073
78.05
3.078
78.18
4451604
544602
1672810
Q
4.045
102.74
4.050
102.87
4451605
544602
1672812
R
4.867
123.62
4.872
123.75
4451606
544602
1672812
T
6.037
153.34
6.043
153.49
4451607
544602
1672813
1. Ring Laps: One set of three (3) ring laps is recommended for each orifice to
assure ample flat laps are available at all times.
A
45°
B Diameter
Figure 61: Drift Pin Specifications