There is special paste to put on stainless steel bolts to stop them seizing, we use it at work and it works a treat. It's loctite product but i cant remember its number. I will look tomorrow if i remember.
Nickel Anti-Seize
Copper-free. Recommended for
stainless steel and other metal
fittings. For preventing corrosion,
seizing, and galling in harsh,
chemical environments, and
temperatures to 2400°F (1315°C).