Managing Innovation Using the Norman Lady and the Höegh Galleon as Case Studies (eBook)

Published Date

January 2002

Managing Innovation Using the Norman Lady and the Höegh Galleon as Case Studies (eBook)

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Using 2 example cases, this paper describes the process of realistically analysing and assessing the effect of operational impacts on a trading vessel. (71pp)

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The NORMAN LADY and the ex LNG CHALLENGER were the first two LNG carriers built to the MOSS Spherical design, and were delivered in 1973 and 1974. At that time Leif Höegh & CO ASA (Höegh) was the owner of the NORMAN LADY and P&O was the owner of the LNG CHALLENGER Being the prototype vessel, the NORMAN LADY was subjected to quite rigorous pressure testing of all the cargo tanks, while her sister, the LNG CHALLENGER was not subjected to the same testing regime.

Both vessels had a somewhat nomadic trading pattern the first years, engaged with partly spot-cargoes of mainly LPG combined with lay-up periods. From 1977, the NORMAN LADY entered into the ADGAS' LNG trade between Das Island in UAE and Japan, and remained under that charter party up to mid 90ties, where after she was engaged by Enagas SA for another 13 years contract of LNG-trading.

The LNG CHALLENGER, which changed her name to LNG POLLENGER, continued her "short-contract" trading, but mainly in LNG-trades up to 1987, when she was sold to a Japanese Consortium, renamed the ASAKE MARU, and put into service mainly between Japan and Indonesia. Later, in 1998, she changed name again, this time to the MYSTIC LADY as she was supposed to be employed in a long-term charter contract with CABOT LNG of Boston, MA after an extensive refurbishment program.

At the end of the NORMAN LADY's engagement in the ADGAS' LNG Project, Höegh engaged Det norske Veritas (DNV) to undertake a Lifetime Extension Study for the vessel, in order to prepare her for another long-term employment contract. The study, which emphasized and focused on the strength of the hull and cargo containment system, concluded that, by relatively simple means, the vessel's life-expectancy could be extended significantly. In late August 1998, as Höegh was about to take technical management of the MYSTIC LADY, (ex LNG CALLENGER), a non destructive test (NDT) of the cargo tanks revealed many smaller hair-line cracks along the welds of the tanks. Several investigations were conducted, and it was soon concluded that the cracks were related to the environment inside the cargo tanks during operation of the ship, or even as far back as during the building of the vessels. The cracks were classified to be Hydrogen Induced Stress Corrosion Cracks (HISCC), which may have been created under circumstances where water had been present inside the tanks for some time (at least 14 days). It was further concluded or anticipated that the cracks were found in all internal welds of all the five tanks on board.

This was of course very alarming news to Höegh, being the operating owner of the sister vessel, the NORMAN LADY. At every dry-docking in the past, the cargo tanks had been checked in accordance with DNV's requirements, with procedures for ultrasonic and liquid penetrant testing (PT), and without any indications of such cracking. As feared, the same kind of cracks were discovered on the Norman Lady, although not to the same extent as on the Mystic LADY. It was decided that at the first opportunity the tanks should be gas-freed and checked. So in October 1998 this work started with NDT personnel from DNV. The tanks were gas freed, and PT was applied along welding seams on a spot-check basis. Steel surface was cleaned with steel brushes to remove oxidation. On completion of the spot-wise control of the first tank, it was concluded that the tank showed no signs of the reported defect, except for two very minor indications that were difficult to interpret. It was decided to grind off the mill scale in these areas for further check.This changed the picture completely! Surface cracks could now be seen clearly, running parallel to the weld, in the heat affected zone, abt. 2 mm from the weld fusion line. The tested areas were done all over again, this time by grinding. It appeared that all the tanks showed this defect, evenly distributed all over. From spot checks of abt. 8% of the total amount of welding, it was estimated that 50-60% of the area was affected.

The reason for the difficulty in detection, we know now, is that the 9% Ni steel has a very tough mill scale, due to the double normalisation it has been through at the steel mill. Over all the years with routine checking, also with PT, this has apparently been under-estimated with regard to its capacity to camouflage the HISC Cracks.

These events, both on the NORMAN LADY and the ex LNG CHALLENGER, led to a process where the best available resources and know-how were utilised, in order to address the problem and develop procedures to resolve the cracks in the cargo tanks, and also to ensure the a reoccurrence would not take place. This paper emphasizes on the process of realistically analysing the opportunities and limitations of the two vessels. Sound innovative thinking, and a scientific approach, combined with extensive experience and know-how in LNG-shipping, enabled Höegh to take the necessary actions to bring the cargo tanks back to their full design potential, and also to carry out the reinforcements and refurbishment necessary to operate the vessels for another 20 years.

The innovative and creative approach also applies to how Höegh develops new projects. In this context Höegh has developed a system for delivering LNG to the natural gas markets, called the LNG Shuttle and Regasification Vessel or SRV

Paper delivered by:
Capt. Jon Andreassen
Mr. Sverre Valsgaard

Prepared for:
Gastech Doha 2002

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: Managing Innovation Using the Norman Lady and the Höegh Galleon as Case Studies (eBook)
Product Code: 4433g154
Published Date: January 2002

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