Australian Pipeline Valve - Installation, Operation and Maintenance Manual
9
WAFER PATTERN CHECK VALVES - ‘SLP’ & ‘SW’ STYLE
“seep” in service. This type of valve should always be backed up with an isolation valve. Even soft seated
valves require a small amount of back pressure before a seal is effected. Similarly, to open the valve the
‘cracking pressure’ will depend on the spring tension. Low cracking pressure springs are available.
4 . 0 M A I N T E N A N C E
No periodic maintenance is necessary, except in the case of the SLP series where external over-rides,
dampners, counterweights, etc., may be fitted which require an external gland packing. In this case the
packing gland may need tightening (unless it is O-ring style).
5 . 0 R E P A I R S
Proper safety equipment and apparel should be worn when preparing to service a valve. Observe the
general safety warnings throughout this catalogue and consult your safety manager and plant manager.
5.1 REPAIR INSTRUCTIONS
Due to the relatively low replacement cost of small diameter standard iron or carbon steel valves
especially under 200 NB (8”), it is usually less expensive to replace the complete valve than to have
maintenance personnel effect repairs.
Flange face gasket sealing surfaces should be scraped clean (avoid radial marks).
5.2 REMOVING VALVE FROM PIPELINE
Only one half of the stud bolts need to be removed (others can just be loosened) when removing the
uni-flap from the line. Of course for flanged and lugged valves, all bolts must be removed.
5.3 DISASSEMBLY SLP SERIES
First ensure all fluids and gases are released from valve before commencing. Protective splash proof and
safety eye goggles should be worn. Unscrew the hinge pin retainers (8) from the body (1). To remove
hinge pin (3) maintain pressure on the spring (5) and withdraw hinge pin (3), pulling it through disc (2),
spring (5), and bushings (6). Take careful note of the spring position then disassemble and remove spring
(5), body bushings (6) and disc (2). The seat is integral. Metal seats are machined finished and can be re
lapped or re-metalised. Seat material can be the same as body or overlaid with 316 or stellite. Soft seat
inserts are pressure and heat bonded into the body (or in some sizes the flap) and must be returned to
Australian Pipeline Valve for repair where viable. Once disassembly is complete, inspect parts for damage
and order replacement parts as required. Use new replacement parts, as required. Use a liberal amount
of general purpose grease on seals and machined mating surfaces.
