I am involved in an industry group compiling/developing recommended practices for the stacking and unstacking of vessels, specifically DP vessels (and rigs). The approach we are taking is not just the deactivation of an asset, but doing so with the end game in mind of bringing it back out.
I have researched this and have found some great information online. However, this information covers just the general process and approach and is not very specific in nature, certainly not for DP assets in particular.
If anyone out there has access to additional information or direction on where else to look it would be greatly appreciated.
Fraqrat and CCaptain do address the main concerns, HVAC for the electronics. Cold stacking is going to destroy the controls in these DP boats. Enough HVAC needs to be maintained to keep these spaces dry, maybe solar panels to keep the fans turning and dehumidifiers running in the enclosed spaces? If this isn’t done while it’s stacked then before anything is energized it needs to be done, everything opened up and dried out before the a/c is turned on so that condensation doesn’t occur. Engine and gear layup/startup is well covered by the manufacturers. Pumps the same.
All spaces that have electronics or any sensitive equipment need to be dehumidified. All sea chest’s need to blanked off. Salt water piping needs to be drained, flushed and filled with preservative and fresh water. Heat exchanger’s and water makers, need to be opened cleaned and left open with gaskets and seals removed and new ones on order for when you put back in service. Exhaust stacks need to be blanked and moisture kept from getting in. All electrical panels need to either be dehumidified or have desiccant packs installed in them. Thruster’s will need to have the oil preserved and be turned over randomly just like the engines and pump,s to keep from seizing up and to renew the internal coating of oil and preservation fluid. Engines, pumps and generators need to be preserved as per manufacturer recommendations. Fuel will need to either be treated or pumped off and fuel tanks cleaned. Be prepared to spend a bunch of money and time to get all the sensitive DP equipment back up and running in an acceptable condition. Probably triple what ever you think as far as time and cost.
Cortec makes all the preservation fluids and desiccant material you will need.
Seconded on the Cortec. It’s a corrosion inhibitor (not a desiccant) that sublimates from a solid to a vapor. They make a kind of cartridge that is specifically for electrical/electronic panels. It has a lot of uses, and like ChiefRob said, they make a lot of products. It can even be used in boiler layup (but I think MarAd has returned to wet layup with hydrazine).
It will be interesting to see the results when someone tries to reactivate these assets. I hope someone has the foresight to track what worked, what didn’t, what was unnecessary, and what was overlooked but shouldn’t have been. Having stacked a few, it sure would have been helpful to have had someone with experience assisting. Ultimately it comes down to money now, or money later, and no one was interested in spending any more than necessary now. For example, obviously thruster OEMs recommend removing thrusters for long term layup, but everyone knows that isn’t going to happen. So it’s a judgment call, and I can’t wait to see if we all had sound judgement. I will say one thing I learned is that many of these layup products would have value during operation to better protect exposed equipment on deck and reduce regular corrosion and waste.
