I think low signal tubes such as found in preamps and phono stages are probably okay.
Power tubes are a somewhat different story. One failure mode is where the getter material which helps maintain the vacuum inside the tube gets used up. Then, the gas that builds up inside the tube ionizes (usually at startupit arcs over) and shorts out the high voltage (B+) supply. This usually results in no more than a blown fuse in a properly-designed amp.
A more serious problem can develop if the tube goes "out-of-bias" in a manually biased power amp. Then the tube can overheat and the glass jacket will crack, again shorting out the power supply. Again, usually no damage should occur in a properly designed system.
At least two other things are important: On is that you make sure that your amps have the correctly rated fuses in them. If the rated fuses are continually blowing then get the amp checked...Don't just plug in bigger fuses as this could create damage to the amp and ultimately might produce a fire hazard.
Another thing is to make sure that the circuit that your system is on is not unnecessarily over-spec'd for the power you realistically need. This can also create a fire hazard as, say, a 40 Amp circuit (which would probably violate the local electric code) might just keep on delivering power to your system even after it has shorted out due to some failure and part of it has turned into volcanic lava.
Power tubes are a somewhat different story. One failure mode is where the getter material which helps maintain the vacuum inside the tube gets used up. Then, the gas that builds up inside the tube ionizes (usually at startupit arcs over) and shorts out the high voltage (B+) supply. This usually results in no more than a blown fuse in a properly-designed amp.
A more serious problem can develop if the tube goes "out-of-bias" in a manually biased power amp. Then the tube can overheat and the glass jacket will crack, again shorting out the power supply. Again, usually no damage should occur in a properly designed system.
At least two other things are important: On is that you make sure that your amps have the correctly rated fuses in them. If the rated fuses are continually blowing then get the amp checked...Don't just plug in bigger fuses as this could create damage to the amp and ultimately might produce a fire hazard.
Another thing is to make sure that the circuit that your system is on is not unnecessarily over-spec'd for the power you realistically need. This can also create a fire hazard as, say, a 40 Amp circuit (which would probably violate the local electric code) might just keep on delivering power to your system even after it has shorted out due to some failure and part of it has turned into volcanic lava.