I moved into a house with an electric hot water heater. The heater is old (11 years) but works just fine. However, the top of the tank has extensive corrosion, especially around the connections for the pressure relief valve and water in/out connections. I just flushed the tank, and there didn't appear to be any sediment (the water was at least visibly clear the whole whole time). I can't figure out how to check the anode rod, as I can't find a nut on the top of the tank (but maybe it is obscured by all the corrosion).
Do I need to worry about this, since everything is working? Or could the corrosion weaken the tank and cause it to explode? Obviously, if the tank fails, I will replace it. But, I'm wondering if its condition is a safety hazard and I need to pre-emptively take care of it.