Being a former property manager, there's a few issues here that need to be hashed out:
First, are the tenants running out of hot water because the temp. is too low on the tank or the tank isn't big enough for all the residents' hot water needs?
Second, most hot water tanks in apartment buildings are in a closet or have their own rooms, which can and should be locked.
Third, if they are caught messing with the tanks, they should be given a written warning and then evicted if they keep it up.
Fourth, If the temp. is too high, I'd be more worried about someone being scalded than a rubber seal going bad. You can buy anti-scald devices.