WATCHING THE WORLD ANOTHER TANKER ISSUE

Weight-saving ship designs using more high tensile steel appear ready to become the latest contentious issue to haunt the world tanker industry.

During the past few months certification societies like the American Bureau of Shipping and Lloyds Register of Shipping have become increasingly concerned that the widespread use of tensile steel in new weight-saving vessel designs could increase the risk of structural failure in inadequately maintained ships.

STRUCTURAL PROBLEMS

More recently, Japanese shipbuilder Mitsubishi Heavy Industries (MHI), Japan, recalled six VLCCs in the 236,000-258,000 dwt range, all delivered within the last 5 years, after cracks were found in the cargo tanks of one of the vessels.

Lloyds List, the London shipping and insurance newspaper, reported that four other MHI VLCCs delivered since 1988 also were being monitored. Cracks were found in the longitudinal frames near the point where they meet the transverse bulkhead and frame.

MHI has six similar VLCCs on order--five for Japanese companies and one for Amoco Corp.--and will make changes in the design when the cause of the cracks is identified.

The concern of the certification societies, combined with problems of the Mitsubishi ships, has reemphasized questions being asked in some parts of the tanker industry about the life expectancy of second generation vessels.

The International Association of Independent Tanker Owners (Intertanko), Oslo, links this concern to U.S. legislation that will require widespread use of double hulled vessels.

Trygve Meyer, director of Intertanko, said increased ballast spaces will be created within the hull of the double hulled vessels, which in turn will create more area for corrosion.

Because the life expectancy of second generation single skinned tankers is uncertain, Intertanko believes it would be unwise to accelerate construction of more complex double hulled vessels that would use similar design criteria without more knowledge about life expectancy.

Meyer said technology involved in second generation vessels is complex. Intertanko technical committees are reviewing the life expectancy and the kind of maintenance programs that will be needed to keep tankers operational.

High tensile steel was first used in tankers more than 20 years ago. It became more common in the early 1980s as shipbuilders looked for cheaper construction methods that would persuade owners to order new vessels at the height of the worldwide tanker depression.

EFFECT ON PRICES, SHIPYARDS

The new designs certainly helped bring down prices. The Royal Dutch/Shell Group, one of the champions of the virtues of well maintained, older vessels, estimates there are 4,500 metric tons less steel in a new VLCC compared with a similar size tanker built 15 years ago.

Shipyards, with bulging order books and a worldwide shortage of construction capacity, are in a position to resist a return to designs of the 1970s.

In these circumstances proper definition of maintenance required for second generation tankers is essential for shipowners and their oil company customers. Failure of a poorly maintained hull anywhere in the world is the kind of accident the oil industry just cannot afford.