Tube failure -- what would happen in worst case?


How do you determine when a tube is to be replaced?
Can a tube ever glow bright red and blow up?
If it does, would it damage the amp itself as well as other components including the speakers?
128x128ihcho
Thanks for all.
I did not bother to bias my tube amp, and I am selling one (Chinese made) and get an amp with auto bias feature (BAT vk60).
Any way, is this a good reference for biasing?
http://www.aikenamps.com/Biasing.html
Any of you have other source?
I guess I was lazy and ignorant. I assumed that a new tube amp was factory biased and I should not fiddle with it, and also I did not want to damage my amp by screwing up. Now I feel like I need to know more about biasing.

If you have to, pay someone to show you how to bias your amp. Small differences in AC voltage can change the bias. Just because the amp is new doesn't mean your house voltage is the same as the factory where the amp was built.

Another good reason to have someone show you how to bias your amp and use the proper tools is so you don't electrocute yourself.