Typical cracks in deck of ship-shaped structures and ways to modify and improve the design

Abstract

Cracks occurred in main deck structure around openings due to pipe penetrations, deckhouses and supports for various equipments have created a major problem and mainly related to the vessels with made of high strength steel material in deck and most frequently found on oil tankers used by buoy loading. This paper will show typical cracks and give guidance on modifications of existing details and examples of good design, where the examples of defects are used from Classification Societies’ feedbacks in hull in operation phase. Any discontinuity or opening in deck as well as attachments to deck has been a problem for years and experience shows that it is difficult to find 100% solutions. The purpose of this paper is therefore not to guarantee perfect solutions but is a selection of good solutions that has proved to be better than most. To avoid cracks in deck completely is not guaranteed and is probably not possible.This paper aims to address with a particular attention on oil tankers but will also be relevant to other vessel types including ship-shaped floating offshore structures such as FSO (Floating Storage Offloading), FPSO (Floating Production Storage Offloading), FLNG (Floating Liquefied Natural Gas) and drill-ships.

Keywords

• Outfitting
• structural defect
• local reinforcement
• shipyard standard
• repair process
• correction