In preparation for an extended yard period, you are reviewing your ship's plans. You notice several bulkheads are labeled A60. What is indicated by the label A60?

Correct Answer: Option D — Fire division boundary, A Class, with insulation that will limit temperature rise below the allowable level for 60 minutes.

The alphanumeric rating 'A60' designates an A-class structural fire boundary insulated to restrict the average temperature rise on the unexposed side below 140°C above original temperature for a duration of 60 minutes during standard fire test exposure.