6AU6A tube question

[kaplang]

just received some new GE 6AU6As with a label on each end of the tube boxes to seal them closed.
Any significance of these labels and the stamp on them? What does do not break at boeing mean?

Thanks

 

[BinaryMike]

The tubes were probably sealed after being tested by Boeing and were intended for spares that would go into the field for maintenance purposes. A broken seal would mean that the tube's condition is indeterminate, making it unsuitable for sale or use in Boeing equipment.

 

[kaplang]

The tubes were probably sealed after being tested by Boeing and were intended for spares that would go into the field for maintenance purposes. A broken seal would mean that the tube's condition is indeterminate, making it unsuitable for sale or use in Boeing equipment.

Makes sense. Thanks!