The 1981 and the 1983 amendments to the International Convention for the Safety of Life at Sea, 1974 (SOLAS) include revised requirements for fire safety measures for tankers. Regulation II-2/59 of these amendments contains provisions concerning venting, purging, gas-freeing and ventilation. regulation II-2/59.1.5 states: “The venting system shall be provided with devices to prevent the passage of flame into the cargo tanks. The design, testing and locating of these devices shall comply with the requirements established by the Administration which shall contain at least the Standards adopted by the Organization’’.
These Standards are intended to cover the design, testing, locating and maintenance of “devices to prevent the passage of flame into cargo tanks” (hereafter called “devices”) of tankers and combination carriers carrying crude oil and petroleum products having a flashpoint of 60 degrees C (closed cup) or less, and a Reid vapour pressure below atmospheric pressure and other products having a similar fire hazard.
By resolution A.519(13) the Maritime Safety Committee was requested by the 1983 Assembly to finalize the Standards for devices to prevent the passage of flame into cargo tanks, the Committee was developing at the time, prior to the coming into force of the 1981 SOLAS amendments.
Devices based upon maintaining a minimum velocity should be capable of opening in such a way that a velocity of 30 m/sis immediately initiated, maintaining an efflux velocity of at least 30 m/sat all flow rates and, when the gas flow is interrupted, be capable of closing in such a way that this minimum velocity is maintained until the valve is fully closed
Devices should be designed and constructed to minimize the effect of fouling under normal operating conditions. Instructions on how to determine when cleaning is required and the method of cleaning should be provided for each device in the manufacturers’ instruction manual
Devices should be capable of operating in freezing conditions (such as may cause blockage by freezing cargo vapours or by icing in bad weather) and if any device is provided with heating arrangements so that its surface temperature exceeds 85 degrees C, then it should be tested at the highest operating temperature.
The dimensions should be at least 4 m circumference, 4 m length and a material wall thickness of 0.05 mm