LUBRICATED PLUG VALVES - SAPM/SAPL
Australian Pipeline Valve - Installation, Operation and Maintenance Manual
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4. If necessary repeat procedure until lubricant is visible inside valve cavity.
Method 2 with hydraulic lever gun
1. Charge the lever gun following manufacturers instructions.
2. Connect coupler of the lever gun to the universal button head of the lubricant screw.
3. Inject the grease by means of hand lever pumping.
4. Turn the plug for even distribution of lubricant.
5. Continue lubrication until lubricant is visible inside the valve body.
Monitor the pressure gauge during the sealant injection process. For sealant to flow onto the valve seats,
enough sealant at sufficient pressure has first to be injected to over come the line pressure, to fill any
cavities in the sealant chamber and grooves, and to overcome the flow resistance through the valve
sealant system.
It is desirable but not essential; to operate the valve either partially or fully after injecting sealant, to
help spread the sealant over the entire seating surfaces.
4.2.2 Valve sealants and lubricants
Only sealants recommended for TAPER plug valves should be used.
Do not use the following types of sealant:
a) Sealant supplied by cylindrical/parallel plug valve manufacturers. These are much higher viscosity than
taper plug valves require and will substantially increase the valve torque.
b) Commercially available lubricating grease such as bearing grease. These greases do not have the
chemical resistance, lubricating and sealing properties required by taper plug valves.
Do not use plug sealant grease for the stem packing where the design requires PTFE plastic packing (see
below explanation). Where an allen key closure system is fitted on the stem sealant nipple, packing
‘sticks’ can be used as stated below. Mushroom head grease nipple may also be fitted.
For leaking valves it is common for operators to use a higher viscosity ‘sealant’ in the sealing grease
channel in lieu of conventional sealant/lubrication. Some types are even laced with Teflon to help seal
even very worn valves. However, special heavy sealants can eventually harden dramatically increasing
torques and blocking grease supply channels preventing the replenishment of replacement lubricant
reaching the critical seating areas. In addition, they can dramatically increase torque. This can happen due
to higher temperatures, lack of maintenance, time, or just due to the nature of the media being handled.
Some sealants can also block secondary check valves inside lubricant fittings. Flushing agents are
available to attempt to clear hardened grease without having to remove the valve from the line. Lighter
sealants (lubricants) are available which enjoy a longer life and tend to harden slower. However, on the
down side these lighter sealants flush away quicker and provide a less effective seal on worn or
corroded valves.
It is important to remember that in small sizes below 50 NB depending on class (typically those without a
flanged top bolt gland) the stem packing is the primary seal and only stem packing compound should be
used to top up the packing, not grease sealant. Grease sealant is only used for the plug/seat area. In
