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Gas
Carriers
Emergency
Shutdown Valves
Measurement of the 30 second limit for closure (from manual or automatic
initiation) to final closure of emergency shutdown valves has been
clarified in draft regulations contained in MSC/Circ.845 to include
signal response time in addition to valve closure time. The valve
must avoid surge pressure in the pipeline and smoothly cut off product
flow. 8.16
Drainage
Systems
To ensure that cargo, leaking from a cargo tank to the secondary
barrier, is collected and returned to a tank other than the failed
tank, a set of draft amendments to the International Gas Carrier
(IGC) Code were approved as MSC/Circ.845. Subject to adoption as
final amendments to SOLAS at a future MSC session, they are scheduled
to become effective on 2 July 2002. The regulations will require
that the drainage system for full and partial secondary barriers
(Type A and Type B Tanks, respectively) return the leaking cargo
to the cargo piping system where it can be appropriately directed
as circumstances dictate. To minimize the possibility of introducing
hazardous products into the machinery space, the draft regulations
explicitly limit the source of ballast water connected to pumps
within the machinery spaces to be ballast piping within the duct
keel, or a wet duct keel used for ballast. 4.4
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