Australian Pipeline Valve - Installation, Operation and Maintenance Manual
7
IRON GATE & GLOBE VALVES - SL201, SL600, SL601
6 . 0 L E A K A G E A C R O S S S E A T
It is always difficult to ascertain whether there is an internal seat leakage unless there is pressure or leak
detection facility in place to monitor any rise or fall in pressure or leakage. Globe valves allow a higher
rate of seat leakage than gate valves, consult appropriate test standard for leakage allowance.
To investigate suspected leakage, the valve should be removed from the line then dismantled. Prior to
removal from line ensure all pressure and fluid is purged from line and valve cavity. Remove disc and
inspect the seating surfaces, also inspect the body seat for any sign or wire drawing/light scratches.
Relap the seats or disc as required if minor damage or else send the valve to an experienced APV
approved valve repair facility. Assemble the valve, should any leaks still persist then the concerned part
may need complete replacement.
When ordering spare parts for replacements, kindly inform us the size, type, rating, part description,
model number and serial number.
7 . 0 D I S A S S E M B L I N G V A LV E S
1. Check that the line is in a complete shut down phase.
2. Pre-order all necessary spare gland packings and jointing gaskets.
3. Open the valve slightly by turning the handwheel anti-clockwise and loosen the gland.
4. Put identification markings on valve body, bonnet, disc/gate, yoke, and actuator. This helps to avoid
mismatching of parts at the time of re-assembly.
5. If the bolts and nuts are too tight, apply deep penetrating oil and then unscrew.
Also refer to details in 12.1, 12.2 and 12.3.
8 . 0 R E A S S E M B LY
1. Re-assemble in reverse order of disassembly.
2. For larger valves, lift up the bonnet using lifting lugs where provided. For smaller valves, gently and
evenly break the bonnet seat with a lever (if required) before lifting the bonnet off (where required
use with a sling mechanical lifting device). Clean gasket surface areas, replace gasket and refit bonnet.
3. Refer Appendix A for bonnet bolt re-tightening procedure.
Also refer to details in 12.4.
