The Ageing LPG Carrier Fleet a Classification Society’s Point of View (eBook)

Published Date

January 1994

The Ageing LPG Carrier Fleet a Classification Society’s Point of View (eBook)

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This paper concentrates on the aging of the hull and the cargo tanks on LPG-carriers as these two elements are most important when considering life time matters. (14pp)

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A classification society will normally not withdraw the class of a ship simply due to the ship's age. Provided a ship is maintained in a classworthy manner, the class may be maintained for an unlimited period. As far as known to the author, this is the general policy of all major classification societies. It should, however, be mentioned that the maximum dynamic design loads in the rules are based on a probability level of occurrence of Q = 10-8, where Q = 10-8 is associated with an assumed life time of the ship of 20 - 25 years. As this load level is also used for fatigue strength calculations, ships becoming older than 20 years should be very critically looked at from the fatigue life point of view. The life time of a ship is normally dictated by commercial considerations, ie the market situation, freight rates, prices for newbuildings, repair costs and, last but not least, the state of the hull, the cargo tanks, the cargo system, the machinery and equipment. These all influence the decision whether or not the cost of a life extension of an aged ship will pay off.

An observation GL has made with a series of container ships is worth being reported in this context: These ships, which sailed between Europe and America over a period of 20 years, ie throughout their lifetime they were exposed to the harsh environment of the North Atlantic, were, after 20 years, really at the end of their life. At numerous locations fatigue failures were found. The owner decided that a repair or reconstruction was not worthwhile. Some other ships of the same type and class, which sailed all their lifetime in the Pacific area, were after 20 years in such a good state that an extension of life beyond 20 years was possible without costly renewals. This experience suggests that the lifetime of a ship is always a case by case decision. Simply phasing-out, based on the ship's age, is not reasonable.

This paper concentrates on the experience with the hull and the cargo tanks of ageing LPG-carriers, because these two elements are most important when considering the life time of LPG-carriers

Paper delivered by:
Martin Böckenhauer (Germanischer Lloyd, Germany)

Prepared for:
Gastech Kuala Lumpur 1994

For over 45 years, the Gastech Exhibition & Conference has been at the forefront of the international gas and LNG market. This world-renowned event is regarded as the most significant meeting place for gas and LNG professionals, where the global industry gathers to do business.

Gastech hosts major IOCs, NOC’s, global utility companies, EPC contractors, shipbuilders, pipeline companies, manufacturers, distributors, technology and service providers, all who play an active role in the global energy value chain.

Title: The Ageing LPG Carrier Fleet a Classification Society’s Point of View (eBook)
Product Code: 4433g073
Published Date: January 1994

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