A question we get asked is what can fail during lay-up. We have been involved in lay-up since 2004 and have decided to highlight some common failures that can occur during lay-up, hot stacking, and warm and cold lay-up. Geographically speaking, it does not matter where your assets are. But, for example, the following conditions could occur.
Hot Layover & Warm Layup
As time passes, waiting for a new contract, there can be a lack of understanding of critical preservation needs. As a result, the crew onboard and management are unaware of basic preservation requirements and planned schedules. In addition, leaving specific systems in standby mode for extended periods can cause corrosion and seizure issues, as well as a reduction in the overall long-term reliability of the equipment.
With warm lay-up, issues are pretty much the same as hot lay-up. Still, as time passes and there is no certainty of when the vessel will reactivate, the problems will become more significant issues. I visited rigs sitting idle in the arrival condition 17 months later. Engines had not turned over with forced lubrication; sea water systems were left full of water with the expectation that they may get the word to reactivate tomorrow. The planned maintenance system has not changed, and equipment maintained based on running hours has not been serviced in a suitable timeframe. For this reason, we have done much work creating warm stacking maintenance variants and supplying essential preservation equipment. The below indicates problems that can be found but are not a complete list.
1. Sea water systems shut down without proper essential preservation.
- Sea water fouling of heat exchangers
- Pipe corrosion due to localised corrosion
- Stagnant water causing stainless fitting corrosion & failure
2. Treated freshwater systems shut down without proper positive pump circulation
- Localised loss of corrosion inhibitor & therefore corrosion
3. Fuel Systems left as per arrival without tank circulation
- Stratification of IFO & HFO fuel systems
- Microbial degradation of fuel left standing for a long time
- Solidification of HFO
4. Engine start systems
- Malfunctioning regulators
- Malfunctioning control systems
5. Funnel Blanks have not been closed, and exhaust spaces are not clean
- Rainwater enters economiser spaces, and localised corrosion occurs
- Hardening of soot due to uncleaned spaces
6. Jack up rig legs get stuck in the mud
- Currently, up to 4-day delays have occurred in Labuan due to this event
7. Transformer oil contamination
- Large transformers with coolant not fitted with a nitrogen blanket as part of an essential lay-up preservation
The atmosphere, especially the humidity, may not have been monitored during lay-up, resulting in corrosion and deterioration.
1. Electronic equipment start-up fails after months without power.
- Electronic Failure
- The equipment did not start when power turned on, such as computers, servers and navigation systems
2. Control system calibration settings off specification
- The hysteresis curve is out of specification and locks the system from starting, such as DP control systems, boiler combustion systems, and other computer or PLC control systems.
3. High moisture levels in electrical/ electronic components
- All products & parts, both electrical & electronic, have operating specifications that generally specify a temperature & humidity range. An enclosed space with no dehumidification will increase the humidity to more than the rating of devices and potentially lead to deterioration and component failure. Lay-up with VCI spray only will cause issues.
- Different battery types have additional requirements, and it does pay to check the class and see advice from the manufacturer
5. Hull fouling
- Sea chest fouling reduces water flow. Growth build-up in tropical waters is fast
- Growth around stern tube seals
6. The impressed current system turned off
- Corrosion in sea chests
- Hull corrosion, subject to paint condition
7. Ships side valve seizing in the closed position
- Unfortunate but true, even with proper lay-up greasing before shutting
8. Corrosion & failure of pressurised seawater pipes or pipes passing through ballast tanks
- Live sea water pipes will always pose an issue and, unless drained and dehumidified, cannot be actively controlled. Preservation by VCI products may assist with this issue, but unless opened and condition assessed, it cannot be guaranteed
9. Machinery sitting static for long periods or turned with improper lubrication
- Pedestal bearings without forced lubrication
10. Dry powder extinguishers
- Compacting of powder due to not being turned upside down monthly
The above is only part of the problem with incorrect lay-ups. MLS can assist in providing a reactivation schedule to identify materials, labour and time to prepare for departure. Proper planning will assist in preparing to leave without unnecessary delays. So, whether you’re sitting at an anchorage or alongside a wharf, MLS can provide you with a consultancy service that suits your needs & budget.