a) Hull Construction. The extent of NDE applied during construction will be governed largely by the type and size of the ship involved. On all ships built to the Rules and Regulations of a Classification Society a number of checkpoints will be monitored so that the quality of welding can be evaluated. On a large tanker for example, hundreds of radiographs will be taken to comply with Classification requirements with an additional several kilometers of welding being ultrasonically tested for quality control purposes. On a smaller vessel, such as a general cargo ship, the extent of applied NDE will be much less and may be restricted to approximately one hundred checkpoints.The results of a review carried out on a selection of new buildings in Europe and the Far East will be used to highlight the significant aspects of shipyard NDE applied to welds in hull structure. The subjects to be discussed include the extent of applied testing, selection of test points, method of inspection, acceptance criteria and the need for corrective actions. The salient points of examinations made on the steel castings which form an integral part of the hull structure will also be discussed. The conclusions reached from the exercise were that the range of checkpoints taken for Class had to be extended to cover key structural configurations and that demarcation between Class and quality control checkpoints had to be removed. These conclusions are discussed.
b) Periodic Inspections. All ships are subjected to a survey at prescribed intervals so that the condition of the ship can be monitored. The extended requirements for thickness testing brought about by the introduction of enhanced surveys will be described together with a review of the limitations of the measurement technique. The impact of enhanced surveys will be discussed.
As previously the method and extent of conventional NDE applied during periodic surveys is influenced by the type of the ship but in this case with an added factor, that being the age of the ship. The problems faced by older ships, particularly tankers and bulk carriers, will be described and the case for the introduction of crack detection techniques for the identification of fatigue cracks will be reviewed.
Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00
Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:
Publication Contact:
7th ECNDT, Park Alle 345, DK-2605 Broendby, Denmark, Fax: +45 46 26 70 11, Email: 101373.3414@compuserve.com
| NDTnet |