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General Information Introduction There have been a number of losses or part losses over the last few years of blocks of pipes stowed on deck, principally on the hatch covers. Much consideration has been given to the reasons for those losses and ways by which such stowage may be adequately secured for the rigours of an ocean voyage. The losses have resulted from one or a combination of the following:-
Before looking at the various technical aspects associated with securing a cargo of deck-stowed pipes, the composition and vulnerabilities of the cargo should be studied. Large-diameter pipes shipped by sea on deck are, in most cases, not simply pieces of break-bulk but are highly sensitive, even delicate, and valuable items. The pipes are often manufactured from special high-alloy steel with great precision, are tested to withstand high pressures, have ends finished to comply with a specification (bevelled, threaded, etc.) and are usually coated internally and externally with varnish, paint or cement. Any damage to the ends or coating is likely to result in rejection of pipe or high costs resulting from refurbishment. As such, large diameter pipes are best stowed under deck, and nothing in this book should be interpreted as encouraging a decision in favour of the shipment of pipes on deck. fig. 1 Pipes are often high-value, precision -engineered items with special finishes. Applicable regulations When it is not possible to stow pipe cargos under deck and they need to be carried on deck, they must be stowed longitudinally - similar to logs. One might therefore consider following the recommendations of the International Maritime Organization's (IMO) Code of Safe Practice for Ships Carrying Timber Deck Cargos, 1991. However, one of the principles behind the securing of a timber deck cargo is that the lashings are satisfactory for normally expected conditions, but not strong enough to retain the cargo on board if it shiftes. This principle cannot be used for stowage of pipes. Code of safe Practice for Cargo Stowage and Securing The characteristics of pipes are vastly different those of logs and stowages of pipes must be secured not as for timber but in accordance with the provisions of the IMO Code of Safe Practice for Cargo Stowage and Securing (CSS Code), particularly annex 13. The CSS Code incorporates general principles for the recommendations to be followed, and some guidance with regard to action in heavy weather and when cargo has shifted. Annexes 1 to 12 contain guidance on the stowage and securing of particular types of cargos and appendices 1 to 5 quote other resolutions and circulars to be considered. Annex 13 gives some guidance and methods for the assessment of lashing arrangements. It gives a definition for the maximum securing load (MSL) and the method for calculating the MSL for lashing materials. Section 7 describes an 'advanced calculation method', which may be used to calculate external forces acting upon cargo and then whether or not the chosen lashing materials and number of lashings to be fitted are sufficient. |
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