4.10 Requirements for cargo handling systems

 The materials for cargo handling systems should be in accordance with recognized standards for the design temperature. The design temperature for the materials should be calculated for the design condition accepted by the Administration.

 All moving parts of cargo handling systems should be adequately secured to the NGHP carrier during voyage to prevent damage to the ship. Securing devices should be provided in accordance with the established securing plan for the cargo handling systems.

  4.10.3.1 At least one set of emergency shutdown systems should be provided for the cargo handling systems. Activation of the shutdown systems should be controlled at a continuously manned station during cargo handling. An established shutdown procedure should be followed automatically or by remote control, following activation of the shutdown system. Cargo handling should be stopped automatically in case of activation of the emergency shutdown systems.

  4.10.3.2 Appropriate means should be provided to suspend cargo handling. Suspension of cargo handling should be controlled at a continuously manned station during cargo handling.

  4.10.3.3 In the case that a cargo hold cover space is filled with natural gas, temperatures of all moving parts of the cargo handling system in the space should be monitored, and the threshold temperature should be determined, based on the ignition temperature of natural gas.

  4.10.3.4 Cargo handling should be suspended in the case that one of the following situations takes place:

• .1 ingress of air to a space filled with natural gas is detected;

• .2 pressure of the spaces containing the cargo handling system becomes below atmospheric pressure; or

• .3 monitored temperature of any part of the cargo handling system exceeds the threshold.

In the context of ingress of air, the recommended alarm level is 30% of the Lower Explosive Limit (LEL).

In the context of temperature, the recommended threshold is 450°C, i.e. the ignition temperature criterion "T1" in standard IEC 60079 (Electrical apparatus for explosive gas atmospheres), taking into account that the temperature class of methane is "T1".