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TAIC CONTINUED … two pilot cylinders had not discharged, so he and the master decided "for safety's sake" to do so. The 20 empty cylinders were taken to a Wanganui company, which refilled them and tested them. All were free of leaks. However, the vessel's managers found that the company was not certified by ABS, the Marsol Pride's classification society, and the job was done again by an Auckland company, certified by ABS, which also fitted new valves. The system was cleaned after the cylinders were reinstalled and several gas nozzles were found to have debris blocking or impeding the gas flow. In analysing the accident, the TAIC said it could not determine why the pilot cylinder leaked. A laboratory examination by Quest Integrity NZL showed the valve had no defects. It had been handled several times since the accident and any foreign debris could have been expelled. "Why the valve on the pilot cylinder leaked is not as important as the second failure: the leaking booster valve." The laboratory had found the booster valve was not in good condition and it was "very likely" that it had leaked gas, causing the gang release of the 18 cylinders, the Commission said. The procedure for clearing the CO2 pipes recommended isolating the booster valve from the pressure manifold, which the service technician had done when servicing the system on May 15. "The integrity of the booster valve was critical to the integrity of the complete system, so it was surprising a physical check of this valve was not included in the maintenance procedure. The technician had checked the valve was opening and closing but did not inspect the actual valve seating arrangement, nor was one specified." The technician said he had used compressed air to test the booster valve for leaks but the compressed air was below the system's normal operating pressure. The Commission said it could not establish how long the booster valve had been leaking, nor how long the debris had been trapped within the valve seal. The laboratory report revealed de-zincification in the brass booster valve piston and valve seat, a process where the zinc component in brass preferentially corrodes or oxidises. The report also said CO2 dissolving in moisture formed carbonic acid, which attacks the zinc in standard brass. "The condition in which this booster valve was found justifies a regular inspection and cleaning of any control valve in other fixed CO2 system." systems that are critical to the integrity of the who le The Commission said its investigation had revealed two key lessons: • vital components in a fixed CO2 gas fire-fighting system should be inspected often enough so any defects can be remedied, and • tests of control valves or other vital components in a fixed CO2 system should be the same as or greater than during normal operating conditions. It said it was concerned that critical components were only required to be internally examined every five years, "and are not required to be tested at the design operating pressure at all." It recommended the International Association of Classification Societies be informed of its investigation, "so they can draw on the lessons learned and consider amending the current guidelines to require a more robust examination and testing regime for such critical components." Save Money And Fuel! We Supply Everyone From Trucking Fleets To Ships In The Ice, Agricultural, Automotive Engineers, Generation, Suppliers. And Now We Are Making It Available To You! Global Leader in Anti Fouling Technology ANTIFOULING THAT PROTECTS 10,000 COMMERCIAL SHIPS WORLDWIDE NOW AVAILABLE HERE FOR YOUR BOAT STOCKISTS: All Marine Norsand Boat Yard Wairau Paint Centre Linkup Paint Supplies Dickson Marine Tissiman Marine Dunedin Shipping Supplies Whangarei 09 438 4499 Whangarei 09 430 8485 North Shore 09 443 3430 Tauranga 07 571 8921 03 546 9024 03 328 7585 03 477 7212 Nelson Lyttelton CONTACT US TODAY: RALPH STARK 021-586-877 Polymer Group Ltd e: sales@polymer.co.nz 0800 999 001 www.polymer.co.nz 72 Professional Skipper November/December 2011 Offi ce 03-329-7834, Fax 03-329-7808 Email: Ralph@newfueltech.com Web: www.newfueltech.com CHORNCO'S PROPRIETARY RANGE OF PRODUCTS, PRODUCE COST SAVING BENEFITS THAT: ■ Reduce noxious emissions ■ Reduce fuel consumption ■ Replace fuel lubricity ■ Improves equipment performance ■ Sustain equipment effi ciency ■ Lower maintenance related costs ■ Eliminate Diesel Bug ■ Extend related equipment longevity VIP.S80 VIP.S68