Although it’s tempting to just flip the switch, a little due diligence before restarting will go a long way. A good start is a visual inspection to check for rust, leaking gaskets, seals, cracks, proper oil levels and oil color.
“If they did take steps to prepare the equipment before they idled it, they should reverse those steps,” Frank said. “If no steps were taken to control moisture contamination, the equipment should be inspected for rust and corrosion.”
He continued, “Surfaces will be dry and should be lubricated thoroughly prior to start up. If there is water contamination, the system should be flushed if possible. Inspect the equipment first--especially any hydraulic and lubrication systems--drain any water off and grab a representative sample of the oil to see if it has degraded. Ideally, though, in order to get a representative sample, the oil should be moving through the equipment.”
Specific tests Frank recommends include Karl Fischer (for water), acid number and additive levels. “In most cases, they wouldn’t need to completely change the oil before start up,” he added.
Although most machinery isn’t restarted in isolation, following are a few examples of procedures to complete before restarting equipment.[1]
STEAM TURBINE
- Confirm nitrogen blanketing inside the lube oil tank is at correct pressure
- Confirm barrier gas supply is at correct flow rate
- Confirm primary and secondary seal gas/oil is in the line
- Confirm pressure differential control valve bypass valve is open
- Drain primary seal filters
- Confirm lube oil header pressure and control oil pressure
- Confirm level in hot well is 50%
- Confirm inlet steam is at proper temperature; emergency stop valve must be closed
- Confirm gland steam supply is at adequate flow rate
- Open startup valve
HYDRAULIC SYSTEM
- Check
lubricant level is at desired level
- If equipped with piston pump, ensure pump housing is also filled
- Confirm valves open on suction line
- Check that pressure control valves, flow control valves and pressure compensators are set to as low a setting as possible, or in last configured setting
- Set directional control valves to their at-rest position
- Charge the accumulators to their specified pre-charge pressures
- Turn on pump
- Bleed the system at the load lines, as far as possible, at highest point
- Operate directional control valves and allow the loads to move in and out several times
- Increase the load slowly
- Increase the setting of the pressure control valves and/or pressure compensators
- Bleeding is complete when no more foam appears in the reservoir, load movements are smooth and no abnormal noises are present
- Check lubricant level after bleeding is complete
GENERIC ELECTRIC MOTOR
- If equipped, energize the space heaters
- If oil
lubricated, check lubricant level is at desired level
- If flood or mist application, turn on oil supply pump
- If grease lubricated, replenish and purge grease
- If equipped, turn on cooling water supply
- Inspect belts or coupling to ensure they are in good condition
- Check to see that machine spins freely
- Confirm all guards are in place
- Turn on motor
The most prevalent failure mode at startup for motors is bearing-related and can include worn bearings, bear housings or shafts. “You don’t want to hit ‘go’ and put it into service right away,” Frank said. “Start it up to see if it is operating properly first. Many problems can be detected by test-running the equipment and performing vibration analysis and/or ultrasound and infrared thermography.”
Matt explained that there are warning signs indicating the equipment needs to be shut down again. These include unusual noise and/or vibration. “Hopefully you would catch that right away,” he said. “Once you notice vibration or noise there’s a chance that the damage has already been done. So shut it down right away.”
If the equipment has been thoroughly
vetted, started in isolation and does well, operators can be confident that it
will perform well once it’s put into production again.
[1] These are generic examples to demonstrate only the extent of pre-startup procedures. Please consult the machinery OEM for specific startup instructions.
