2.6 COMMISSIONING
The first year of operation is crucial, because when the pipe is put into service, all debris is pushed
downstream, and contaminates the valves along it’s travels. With time, the pipe gets cleaner and initial
problems disappear. Strainers or filters should be installed upstream of all soft seated valves.
The same recommendations regarding grease injection for flushing (see 2.4) apply for commissioning. By
refilling the grease channels multiple times, the dirt is gradually pushed out of the seats. Provided that
the grease is properly chosen (see 2.4), it will not damage the valve, and to a certain extent will shield
the seats from contamination. Regular cycling is also important, for two reasons: to prevent the seats
from getting stuck, and to distribute fresh lubricant over the seating surfaces of the gate and seats. Once
the seat is greased, it is a good idea to pump fresh grease into the seat to expel any debris laden grease
(see 2.4) before cycling the valve to avoid damage to soft seat inserts. Should you need to apply grease
to seats, ensure you then inject fresh grease to dispel any grease which may have attracted contaminants
and then partially stroke the valve multiple times to remove as much grease as possible from the seats.
After commissioning, once you believe the service is clean you can inject a suitable grease line flushing
agent and then partially stroke the valve again. You should consult a valve maintenance specialist as
different service, media, pressures and temperatures, etc., can require totally different practises. APV
recommends the following programme for start up: -
1. For the first year, inject a small amount of grease into the seats before turning the valve, every time.
2. Cycle the valves periodically as follows:
• For the first month, every week.
• For the second month, every two weeks.
• For the third month, every month, for at least 6 months.
• Then every three months.
Carefully select the type of seat inserts to suit the type of particulates encountered in the media. Nylon
and Devlon are hard and resistant to scratching, PEEK is even harder. Teflon® (PTFE) is softer and scratches
easier, yet it can have more resilience and ‘memory’ in terms of resistance to permanent indentations but
has a lower pressure rating. However, all soft seated valves are only suitable for clean service ‘metal to
metal’ seated valves are required for dirty or higher temperature service. Regardless of soft seat
materials, valves need to be regularly partially stroked to prevent sticking of seats and accumulation of
entrapped debris.
Australian Pipeline Valve - Installation, Operation and Maintenance Manual
11
API6D THROUGH CONDUIT EXPANDING GATE VALVE - AP400-405 SERIES
Note
Remember that gate valves are like the human body; they need ‘exercise’. Keep
moving them and lubricating them, and you will have fewer problems. Do not let
them have a sedentary life.
