Australian Pipeline Valve - Installation, Operation and Maintenance Manual
15
LUBRICATED PLUG VALVES - SAPM/SAPL
One of the most common problems associated with seat leakage is the lack of sufficient sealant to
adequately fill and pressurise the sealant system. Introduce the correct amount of sealant into the valve
and again check for seat leakage.
If a non-compressible fluid is trapped in the centre cavity of the plug, when the
valve is in the closed position, injecting sealant at high pressures or high volumes
can cause the plug to lock in place. This can also cause the cover bolts to yield,
resulting in bonnet leakage.
4.2 VALVE LUBRICATION OVERVIEW
The valve must be fully OPEN or fully CLOSED otherwise all four grooves on the supply channels will not
be connected. Only an expert trained plug valve maintenance specialist should undergo maintenance.
Sealant can be injected whist the valve is in-line and under full working pressure. The following is only an
indicative summary of procedures.
APV lubricated plug valves are designed to be lubricated using two different methods
- Via built-in lubricant screw using grease sticks.
- With hydraulic lever gun.
Insert the correct size and type of sealant stick into the threaded hole, and screw in the injector.
Depending on how much sealant is in the valve will determine how many sealant sticks may need to be
injected. Initially the sealant injector should turn on easily, while the sealant chambers are filling up.
Once these are filled, it will become more difficult to turn, but keep turning the injector to inject more
sealant. After it has become difficult to inject sealant, it will suddenly become easier as the plug is lifted
off the seats - at this point inject another half a stick and then wait about 5 minutes for the sealant to
flow around the seats. Inject more sealant until it is flowing easily and the valve is operating easily.
Take care when removing the injector, in case there has been any leakage of the
service medium through the double check valve.
Method 1 via built in lubricant screw (where applicable)
1. Remove lubricant screw and introduce grease stick into the stem reservoir. The check valve in the
reservoir eliminates the danger of any loss of grease during loading.
2. Replace the lubricant screw and tighten down to pressurise the grease which is forced past the check
valve into the upper chamber and then into the lower chamber via the groove machined into the plug.
The grooves are positioned so that they are never exposed and cannot be entrained by the process
fluid.
3. Rotate the plug to evenly distribute lubricant.
