Cameron TYPE 31 Installation, Operation And Maintenance Manual page 9

Double-Block-and-Bleed
Whether in the open or closed position, pressure
on each side of the ball is blocked from the body
cavity by the seat ring. The body cavity can then
be blown down or drained through the body port.
Take the following steps when block-and-bleeding
a valve:
WARNING: Make sure proper safety garments
are worn, and follow all customer safety
procedures. Failure to do so could injure
you or others.
1. The CAMERON bleed fittings have one or two
exhaust ports. You should be aware of their
orientation. Any debris in the valve or fitting
will be exhausted at a high velocity.
2. If necessary, tighten the fitting to reorient the
exhaust ports.
3. With the valve fully open or fully closed, open
the bleed fitting all the way. When opening the
bleed fitting, a backup wrench may be used to
prevent accidental removal of bleed fitting.
The process of block-and-bleeding the valve is
intended to test the valve integrity.
If the valve does not blow down, this indicates that
the seats are leaking. Consult the Troubleshooting
section.
WARNING: Never try to block-and-bleed the
valve in the partially open position.
Failure to do so could injure you or others.
Seat Cleaning
The seat pocket area is the primary area where
any valve can be affected by contaminants in
the lines. To insure the seat's free movement,
it is recommended that the valve seat pockets
be cleaned routinely with an approved product.
(The frequency of routine cleaning depends
on the severity of service, but once a year is a
good guideline. Contact your Cameron Valves &
Measurement group representative for assistance).
Cleaning procedures can be found on page 10.
Installation, Operation and Maintenance Manual
E N G I N E E R E D V A L V E S
Figure 10 - Valve Closed. Figure 11 - Valve Open.
Figure 12 - Typical Bleed Fitting.
Figure 13 - Cameron T31 Seat Section.
Gear Maintenance
The following gear maintenance should be
performed along with the valve maintenance:
1. Inspect housing for damage and wear.
2. Inspect weather seal and replace, if damaged.
This will prevent water from entering the
gearbox and causing corrosion.
3. Lubricate gear, using an approved lubricant.
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IOM-CAM-BALL-T31