Oilman,
The process equipment is frequently designed for vacuum conditions;- do not confuse with a non-process condition design of 'steam-out' condition, which occurs at relatively low temperature, low pressure. However, this condition could lead to some level of vacuum in an blocked vessel, pipe, etc. In many cases the process engineers prefer to specify full vacuum at ambient temperature as complement to the steam-out condition.
Yes, a Reboiler is frequently designed for full vacuum condition, for process reasons and/or steam-out condition.
Cheers,
gr2vessels