In a similar case, we worked out with the supplier a strategy which worked well. I assume the exchangers are made of carbon steel if you mention corrosion.
After hydro, we dried 100% the exchangers by vacuum drying method, then replaced the vacuum with Nitrogen around 3-5 psi and locked the valve. Hanged a logbook on the valve and hooked a small bottle of Nitrogen to the valve. Twice a week someone checked the pressure gauge and let some more Nitrogen in the exchangers, if needed. This was also followed up on the barge transport to the site, particularly to prevent the ingrease of salty air on the deck (we were afraid the exchangers would expand in the sun and the 5 psi pressure would turn in vacuum...). The N2 bottles were only removed when the exchangers got bolted down on site. Inside perfect new after 11 months of storage and transport.
cheers,
gr2vessels