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1 Basic Classification System

Marine fire doors are classified into Grade A, Grade B, Grade C in descending order of fire resistance performance in accordance with the SOLAS (International Convention for the Safety of Life at Sea) Convention and classification society specifications. A special Grade H is additionally established for high-risk scenarios.

The grade of a fire door must match the fire-resisting division grade of the bulkhead/deck where it is installed, so as to ensure the integrity of the ship's fire compartments.

 

2 Detailed Classification and Requirements for Each Grade

2.1 Grade A (Highest Grade)

Core Definition: Applied to Grade A fire-resisting divisions with steel structure; it shall pass the 1-hour standard fire resistance test, maintain structural integrity and prevent the passage of smoke and flame.

Key Features: Must be steel self-closing doors; generally required to be remotely closed (operated from central control room/bridge) with real-time on/off status display.

2.2 Grade B (Intermediate Grade)

Core Definition: Applied to Grade B fire-resisting divisions, manufactured from non-combustible materials; it shall pass the 0.5-hour standard fire resistance test, maintain structural integrity and prevent the passage of flame.

Key Features: Lighter in structure than Grade A doors, commonly made of composite rock wool panel material; equipped with self-closing function as standard.

2.3 Grade C (Basic Grade)

Core Definition: Manufactured from approved non-combustible materials with no specified fire resistance duration requirement; mainly applied to Grade C fire-resisting divisions to provide basic fire separation functions (CCS).

Typical Application Scenarios: Storage lockers, low-risk utility spaces, areas without strict thermal insulation requirements.

Key Features: The simplest structure; no mandatory self-closing function; no special approval from the competent authority required (distinguished from Grade A and B) (CCS).

2.4 Grade H (Special High-Risk Grade)

Core Definition: Designed for high-risk scenarios; it shall pass the 2-hour standard fire resistance test, maintain structural integrity and prevent the passage of smoke and flame, with the same thermal insulation requirements as Grade A.

Key Features: Mainly used for ships or offshore facilities with higher hazard levels, with more stringent structural requirements; generally made of thickened steel plates.

 

3 Core Basis for Grade Classification (Fire Resistance Performance Indicators)

 

4 Application Principles

4.1 Matching Principle

The grade of a fire door must be completely consistent with the grade of the fire-resisting division where it is installed (e.g., A-60 bulkhead must be equipped with A-60 fire door).

4.2 Location Principle

·        Grade A: Key areas such as engine rooms, cargo holds, external walls of accommodation areas on oil tankers

·        Grade B: Internal areas such as accommodation cabins, public spaces, corridors

·        Grade C: Low-risk storage areas, non-crowded spaces

·        Grade H: High-hazard environments such as offshore oil and gas facilities, liquefied gas carriers

4.3 Function Principle

·        Grade A and B doors must be equipped with self-closing function to ensure automatic closure in case of fire.

·        Grade A doors in important areas shall be equipped with remote closing function and real-time status display.

 

5 Summary

The grade classification of marine fire doors is an international standard based on the SOLAS Convention, with the core purpose of controlling the spread of fire through compartment division and protecting personnel safety. The selection and installation of marine fire doors must strictly comply with the ship's Fire Control Plan to ensure that the grade is fully in line with the specification requirements of the installation location, which is a critical line of defense for ship safety.