What is the difference between A0 and A60?

“A” class divisions

“A” class divisions are as defined in SOLAS regulation II-2/3.

Source: IMO Resolution A.1023(26), Code for the Construction and Equipment of Mobile Offshore Drilling Units (2009 MODU Code), 2009. Global Standards

“A” class divisions (fire divisions)

‘A’ Class divisions are those divisions formed by bulkheads and decks which comply with the following criteria:

(a) They are to be constructed of steel or other equivalent material.

(b) They are to be suitably stiffened.

(c) They are to be so constructed as to be capable of preventing the passage of smoke and flame up to the end of the one-hour standard fire test.

(d) They are to be insulated with approved non-combustible materials such that the average temperature of the unexposed side will not rise more than 140°C above the original temperature, nor will the temperature, at any one point, including any joint, rise more than 180°C above the original temperature, within the time listed below:

Class ‘A-60’ – 60 minutes

Class ‘A-30’ – 30 minutes

Class ‘A-15’ – 15 minutes

Class ‘A-0’ – 0 minutes

(e) In accordance with the Fire Test Procedures Code, a test of a prototype bulkhead or deck may be required to ensure that it meets the above requirements for integrity and temperature rise

Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 7, Safety Systems, Hazardous Areas and Fire, June 2013, Lloyd’s Register, Global Standards