not very likely to happen i assume, but just take a look at this :P
(mind you door is indestructible)

You can break open most doors (keycard doors are the exception to this). Vault doors have armor and more HP. but will still break upon attack.

At the very start of a CallistoL6(MS1437)Infestation map, there was only one door and it was pink, so I thought it was a bug.
But I succeeded in destroying the door; so maybe it was a feature?
I found the Unlock on the opposite corner of the map.