Guide to Safely Storing and Maintaining Large Ocean-Going Vessels During Extended Layup

Question:

Hello everyone, I am a project engineer responsible for overseeing the maintenance and repair of 8 large ocean-going vessels. Due to economic circumstances, my organization has decided to place 4 of these ships in "deep layup" for an unspecified period of time. When these ships are eventually reactivated, we will have a 30-day window to bring them back to full operational capacity. Our plan is to have all four ships docked closely together with a small maintenance and repair team on standby. I am seeking advice as I have no prior experience in storing equipment/assets for an extended period, especially in a marine environment where corrosion protection is crucial. I am looking to balance the costs of deactivation, ongoing maintenance, and equipment preservation with the reactivation expenses, timeline (anticipated 30 days), and unforeseen failures that may occur. The systems that need attention include the propulsion system (gas turbines, large gearboxes, hydraulic and fuel pumps, babbitt shaft bearings), compressed air (piping and compressors), potable water (piping, pumps, tanks), sewage (piping, treatment system, holding tanks, pumps), saltwater cooling (pumps, piping), fresh water cooling (pumps, piping), hydraulic systems (pumps, piping, valve blocks, rams), electrical systems (diesel engines, generators, switchboards, transformers, motors, automation systems), saltwater ballast (pumps, piping, tanks), and miscellaneous gearboxes (winches, etc). Any guidance or tips on how to properly store and maintain these systems during the layup period would be greatly appreciated. Thank you in advance for your assistance.

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Matt, you are facing an intriguing challenge ahead. Allow me to provide some initial suggestions, with more contributions likely to follow. In regards to your Propulsion System (including gas turbines, large gearboxes, hydraulic and fuel pumps, and babbitt shaft bearings), consider spading off the compressor inlet and flue gas to stack flanges and maintaining the rotors in a low-pressure dry air or nitrogen atmosphere with a dewpoint of -10 to -20F. It is also recommended to turn the shaft 270 degrees every month and regularly clean and lubricate all fuel injection nozzles and piping, especially when using heavy fuels. Additionally, make sure the large gearboxes are filled with lubricating oil, adding nitrogen purge and rotating the rotor assembly monthly if seals are likely to leak. If feasible, replace the babbit bearings with brass sleeve rings or lubricate shafts at babbit with graphite paste if not. When it comes to Compressed air systems (piping and compressors), implement a low dewpoint air/nitrogen purge to maintain it under 2" water pressure. For Potable water systems (piping, pumps, and tanks), consider using a low-pressure dry nitrogen blanket after draining the system to reduce costs. Sewage systems (piping, treatment system, holding tanks, and pumps) require individual attention, as do Salt Water Cooling (pumps, piping) systems that may need sea water drained and replaced with fresh water. Applying a nitrogen blanket or permissible bactericides may also be necessary. Fresh Water Cooling (pumps, piping) systems should either be kept running or drained and blanketed with nitrogen, with cooling tower internals painted accordingly. Hydraulic systems (pumps, piping, valve blocks, and rams) should be kept filled with hydraulic oil, with system running occasionally if possible. Electrical equipment (diesel engines, generators, switchboards, transformers, motors, automation systems) will need occasional operation and maintenance. Salt Water Ballast systems (pumps, piping, tanks) should be treated like other salt water systems, while Miscellaneous gearboxes (winches, etc.) should follow similar maintenance procedures. It is important to note that exceptions may apply depending on the specific circumstances. Also, consider addressing Hull corrosion and barnacle issues, as well as giving attention to the rudder and its actuator.

Thank you, Vee, for your input. Your advice aligns well with our internal discussions and research findings online. It's reassuring to know we are on the right track with our efforts. When it comes to hull cleaning and maintenance, our plan is to thoroughly clean the hull and polish the propeller using commercial divers if we decide to recommission the ship for an extended period. Furthermore, as regulatory requirements mandate periodic dry dockings, we will take advantage of those opportunities to clean and paint the underwater hull. I also understand the importance of including the rudder in the maintenance plan to prevent potential costly issues in the future. Thank you for your insights. Best, Matt

Last week, I stumbled upon a fascinating Discovery Channel program discussing the Navy's practice of mothballing fleets for future use. The show highlighted the meticulous process the Navy undertakes to maintain these ships in a state of readiness. For more information, you may want to explore the public domain documents available on the Department of Defense (DoD) website. This could be a valuable resource for those interested in learning more about this topic. Consider checking it out! - Aubrey

While not specifically aimed at maritime vessels, the publication "Guidelines for the Mothballing of Process Plants" (MTI Publication No. 34) by R.J. Twigg may still be helpful.

I am also interested in finding cost-effective options to store my water treatment tanks and piping.

From my experience with long-term equipment storage, the most important step is the initial deactivation or mothballing process. Ensure all systems are cleaned thoroughly, particularly of any salt or other corrosive elements. Drain all fuel and water systems to avoid stagnation and rusting, and use appropriate corrosion inhibitors where necessary. You may also want to consider filling key systems with a protective oil or a corrosion preventative compound for that extra layer of protection. The electrical systems should be isolated and switches left in the open position, but do consider installing dehumidifiers if your budget allows, as this helps avoid moisture damage. For ongoing maintenance, regular inspections are crucial to catch any issues before they escalate. Given the marine environment, on top of the normal checks, special attention should be given to any metal components for signs of corrosion. For your reactivation process, while it's tempting to rush equipment back into full service, I suggest a phased approach. Test components like engines or pumps in isolation if possible, before integrating the full system. This will allow you to spot potential issues without risking damage to the entire equipment setup. Remember, prevention is always cheaper than repair. Although it might seem expensive upfront, it will save you a lot of money in the long run. Good luck with your project.

Hi there! Marine Engineer here. What you're undertaking is not a walk in the park, but don't worry – it's manageable. A few tips: for your propulsion and other hydraulic systems, try applying a layer of protective oil or lubricants as they can seal against moisture and stop rusting. For components using compressed air, it would be beneficial to drain them completely to prevent condensation build up which leads to corrosion. Your electrical system run a high risk of damage in saline air, so consider liberal use of moisture displacing sprays and potentially increase insulation in crucial areas. Ballast tanks are often overlooked, but they need thorough cleaning and drying before sealing off. Lastly, always keep maintenance logs - a clear record of past actions can save you a world of trouble during reactivation. It might be worth hiring a specialized marine layup company if things get too overwhelming. Don't cut corners! Good luck!

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Frequently Asked Questions (FAQ)

FAQ: 1. What are some key considerations for safely storing and maintaining large ocean-going vessels during extended layup?

Answer: Answer: Some key considerations include corrosion protection, ongoing maintenance, equipment preservation, and having a plan for reactivation within a specific timeframe.

FAQ: 2. How can I balance the costs associated with deactivation, maintenance, and preservation of the vessels during layup with the expenses and timeline for reactivation?

Answer: Answer: Balancing costs involves careful planning, prioritizing critical systems, monitoring the condition of stored equipment, and having a contingency plan for unforeseen failures during the reactivation process.

FAQ: 3. What are the critical systems that need attention when storing large ocean-going vessels, and how should they be maintained during layup?

Answer: Answer: Critical systems such as propulsion, compressed air, potable water, sewage, cooling systems, hydraulic systems, electrical systems, ballast systems, and miscellaneous gearboxes need proper maintenance protocols including regular inspections, preservation treatments, and monitoring for any signs of deterioration.

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