Australian Pipeline Valve - Installation, Operation and Maintenance Manual
EXPANDING SEAL PLUG VALVE DOUBLE BLOCK & BLEED API6D - TWIN SERIES
To change operator heads:
a. Close APV valve extra tight.
b. Remove snap ring and drive out trunnion pin.
c. Remove housing mounting bolts and lift off the operator.
d Replace new operator in reverse order.
e. Check operation of valve.
f. Lubricate operator every year, while in the open position, with a good grade Lithium-base, extreme
pressure (E.P.), multi-purpose grease.
g. APV valves have a thermal body relief valve assembly to relieve body pressure build-up caused by
thermal expansion of the liquid media when the valve is in liquid service, to prevent the internal cavity
pressure from rising above the shell pressure rating of the valve. The APV valves, as well as other of it’s
type, must have a thermal relief system to enable them to be remotely operated by electrical
hydraulic actuators.
The standard APV relief assembly contains a thermal relief valve, set at 25 PSI differential that is piped
across one of the seating slips.
APV valves with this self-contained thermal relief assembly should be installed with the discharge of the
thermal relief valve piped to the upstream side of the valve. If, after the APV valve is installed in the line,
it is noticed that the thermal relief assembly is piped to the downstream port, the tubing should be
switched to the upstream port.
There is a half-inch manual isolation valve connected between the thermal relief valve and the upstream
port. The manual valve should always be left open and is normally closed only for maintenance purposes
and hydrostatic testing.
The other type of relief assembly uses a thermal relief valve piped to the atmosphere. This valve is
normally set slightly higher (10%) than the working pressure of the valve and is located adjacent to the
body bleed valve.
Please refer to as-built drawing as each size & class can have variations in design.
Note
If a leak is indicated at the body bleed valve, the isolation valve should be closed,
which will indicate if a leak is from a damaged seat slip or a leaking thermal relief
valve. If the leak stops when the isolation valve is closed, the thermal relief valve
needs to be replaced.
Do not overfill housing with grease
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