What is meaning of Class A division Bulkhead ?

(1) “A Class divisions” means the divisions formed by bulkhead and decks and are �

1. constructed of steel or other equivalent material;
2. suitably stiffened ;
3. so constructed as to be capable of preventing the passage of smoke and flame to the end of the one-hour standard fire test;
4. insulated with approved non-combustible materials in a manner that the average temperature of the unexposed side does not rise more than 39.C above the initial temperature, nor does the temperature, at any one point, including any joint, rise more than 180.C above the initial temperature, within the time specified in column (2) of the Table below in relation to the classes specified in the corresponding entry in column (1) of the said table

Table

class “A-60”                                                                               60 minutes

class “A-30”                                                                               30 minutes

class “A-15”                                                                              15 minutes

class “A-0”                                                                                 0 minutes