Oil platforms, destroyers and frigates—case studies of QinetiQ's marine composite patch repairs

Abstract

Composite patch repair solutions offer many advantages over conventional repairs to marine structures such as avoidance of hotwork (welding) and the ability to seal cracks. QinetiQ has been carrying out patch repairs to marine structures for over 20 years. The following case studies of QinetiQ's marine patch repair work will show how these advantages have produced clear benefits for the operators of the vessels involved. QinetiQ has patch repaired Type 21 frigates, Type 42 destroyers and offshore oil platforms as well as developing a number of other composite repair techniques to marine structures. During this work QinetiQ has trialed the patch fabrication techniques of hand layup, resin infusion and prepreg, and the advantages and disadvantages of the methods are discussed. QinetiQ is also trialling the Alternating Current Potential Difference (ACPD) crack monitoring technique on board two Royal Navy vessels and this technique is also discussed. The wider use of composite patch repairs to marine structures is held back by a lack of repair schemes approved by the classification societies. QinetiQ is working with those classification societies and operators of marine vessels to increase our understanding of the effectiveness of composite patches and to develop effective non-destructive examination (NDE) techniques to inspect patch repairs. This will increase confidence in patch repairs leading to their wider acceptance on marine structures. Progress on this work is reported here.