Two separate sections of steel ventilation trunking from the cargo hold passed through the forward store and emerged at ventilators on the main deck. Flexible bellows were fitted each side of two extraction fans in the trunking and investigators found that three of the four bellows had been cut, allegedly by an earlier crew to allow the draining of sea water from the trunking and also to facilitate the removal of cargo residues drawn into the trunking from the cargo hold. These cuts allowed oxygen depleted air from the cargo hold to directly enter the forward store. As the cargo ventilation system had been unused for some time the implications of cutting the bellows had not been recognised.

The vessel's Bill of Lading listed the cargo as steel turnings and was not considered as hazardous by the terminal managers in the loading ports. The correct Bulk Cargo Shipping Name (BCSN) for the IMDG Class 4.2 cargo was Ferrous metal borings, shavings, turnings or cuttings in a form liable to self heating (UN No. 2793) and is described as substances liable to spontaneous combustion. Self heating or inadequate ventilation can lead to a dangerous depletion of oxygen in the cargo hold, particularly if it is carried in finely divided form or allowed to get wet.

Although the level of O₂ in the forward store at the time of the accident could not be determined, the O₂ level in the cargo hold was measured at 6% when the hatch covers were initially opened. Data reproduced in the report stated there is significant risk to life if the atmosphere contains less than 18% by volume of O_2.

The report identified a number of parties involved in the fixing of the cargo with different understandings of the nature and status of turnings within the various regulations. Those involved have since amended their procedures including improving the communication links, particularly with the ships master. The Document of Compliance issued by the Sava Lakes Classification Society stated that ferrous metal, borings, shavings etc were not allowedto be carried. It was noted however that the carriage of other materials capable of oxygen depletion was permitted and that a similar accident could have happened carrying these cargoes.

The status of the forward store was explored. Although the Bulk Cargo Code advised that spaces adjacent to those where a hazard is known to be present may contain an unsafe atmosphere, the forward store had not been considered to be an Enclosed Space. It was noted that if the compartment had been designated an Enclosed Space the accident could have been avoided as the crew would have entered the forward store only after applying the usual precautions for entering such spaces where the presence of the dangerous atmosphere would have been established.

The MAIB makes a number of recommendations to the vessel's Ship Manager, The Bureau of International Recycling and ICHCA International Ltd., the International Chamber of Shipping and the Institute of Chartered Shipbrokers. As mentioned, action has already taken by the Ship Manager and other parties involved. The MAIB have also produced a Safety Flyer summarizing the issues identified. The report notes that 15 deaths and 31 reportable injuries have occurred in similar accidents to the Sava Lake tragedy on UK registered vessels, or in UK waters since IMO Resolution A.864(20) Recommendations for Entering Enclosed Spaces Aboard Ships was adopted in 1997.

The report and the flyer can be view at www.maib.gov.uk

By Peter Barker