Tube Question is 5687 tube same as 5687WA??

Hey Ho tubeheads!

I just want to make sure that a 5687WA tube can be used to replace a 5687 tube in my SF Power 2 amp. What does the 'WA' mean anyway?

Thanks a bunch!
I don't know what WA actually stands for but it indicates a ruggedized tube designed for industrial and military applications. It can be substitued for a 5687, and a 5687 can be substituted for a 5687WA in most audio applications since it will not be subjected to the extreme conditions the WA was designed for.
If your equipment was designed for the WA, the regular may not handle enough voltage. If you have the regualar and want to move up to the WA, go right ahead.

oh...I forgot to mention that the 5687 is a Phillips US tube and the 5687WA is a Raytheon tube.

Thanks Herman & Elevick for the response!
This link will take you to a wealth of tube data. Elevick is correct that a circuit designed for the maximum plate-cathode voltage a WA can handle (330V) will exceed the maximum of a non WA (300V). Most circuits are not designed at the maximum operating points but you should check to make sure.