Devices to prevent the passage of flame into cargo tanks

Following concern expressed in relation to the testing of PV valves for cargoes with low MESG, MSC/Circ. 677 was amended.  The circular will now make reference to electrical apparatus groups in order to define the MESG of products and require testing with specific substances for those products with low MESG from January 2013 as follows:

“…..devices for chemical tankers certified for the carriage of products with MESG less than 0.9 mm should be tested with the following media based on the apparatus group assigned per column i’’ of the IBC Code chapter 17:

.1     Apparatus Group IIB – ethylene (MESG = 0.65mm)

.2     Apparatus Group IIC – hydrogen (MESG = 0.28mm)” 

Click here to view circular on amendments

Since at the time of the amendments more than 50% of the low flash products in the IBC code had no information on electrical apparatus groups a circular was issued listing those products for which this information was missing and requesting that the relevant data be provided to the IMO.   Amended carriage requirements for these products can be found in List 1 of MEPC.2/Circ.17.

The amended testing requirements will apply to existing ships by the first dry docking on or after 1 January 2013.  Before that date ship owners are advised to check the manufacturer's name and model number and the certified apparatus group or MESG of the valves on their vessels.

Criteria for acceptance of certification of valves against the Apparatus Group for flammable products are summarized below: