Maintenance of aged ships and offshore structures

Ch. 15 of the book "Condition assessment of aged structures", edited by Prof. Jeom Paik and Robert Melchers. This chapter overviews the maintenance of ship and offshore structures, introducing first preventive maintenance and protection methods. Especially as far as corrosion is concerned, protection is necessary since this degradation effect is unavoidable for materials used in shipbuilding and it is economically unfeasible to use corrosion free materials. Temporary repairs are then examined, mainly referring to current onboard practice: even if several standards and regulations exist, harmonization and integration is still to be achieved and surveyors’ skills and experience govern. Actually, for temporary repairs, decisions need to be taken on a case by case basis considering not only technical issues but also operational and safety constraints. Permanent repairs of degradation effects are presented, which are largely based on the same criteria of new building. Structures deteriorated above the acceptable limits are generally replaced by cropping and renewing. Attention should be paid to causes of degradation and fabrication of new parts in order to avoid even worse and quicker damages. Examination and tests of repairs are finally summarized briefly.