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Baker Hughes
© 2020 Baker Hughes Company. All rights reserved.
A. General Information
The 1811 Safety Valves are easily maintained. Normal
maintenance usually involves:
• Disassembly
• Cleaning
• Component Inspection
• Lapping the Seats
• Reassembly
• Setting, Testing and Resealing the Valve
Occasionally, remachining the seat bushing may be
necessary to extend the service life of the valve. In any
case, keep all parts for each valve together or marked
to insure that they are replaced in the same valve.
The following tools are recommended for normal
maintenance and following remachining:
1. Flat lapping plate, (for resurfacing ring laps) - Part
Number 0439004
2. Grinding Compounds
3. High temperature thread lubricant - (Fel-Pro, Nickel
Ease, or equivalent)
4. Two (2) ring laps per valve size and type
Note: See maintenance Tools and Supplies in
Section XVI.
All of the above tools can be purchased from Baker
Hughes, with prices in effect at the time of delivery.
It may not be necessary to use all of the ring laps at
any one time, but having a sufficient supply on hand
will save reconditioning time during a boiler outage.
After the boiler is back in operation, the ring laps can
be reconditioned on the flat lapping plate. Lapping
compound, when used with ring laps, wears off the
seat surface on the disc or seat bushing, but it also
wears off the flat surface of the ring lap. A lap should
not be used on more than one valve without being
reconditioned.
Lapping procedure for reconditioning the seating
surfaces of the disc and seat bushing is outlined in
Section XI.C.
XI. Maintenance Instructions
After the parts have been determined to be reusable,
proper machining technique must be employed in
reestablishing disc and seat bushing dimensions.
On 1811 valves, the seat bushing should be machined
in the valve base to insure proper parts alignment.
When chucking the valve base or disc into a lathe,
alignment must be within .001” (0.03 mm). Total
indicator runout at the points indicated on Figure 6 as
“A”, “B”, and “C”.
A
A
B
B
C
C
Chuck Jaws
Chuck Jaws
Figure 6
B. Machining
Note:
Thermodisc™ Discs can not be machined without damaging the lip thickness.
See section XII.B for rework dimensions for the seat bushing and Flat Solid Discs.
