This International Standard defines the minimum requirements for qualification, application, testing, handling, storage and transportation of new and existing wet thermal insulation systems for pipelines, flowlines, equipment and subsea structures in the petroleum and natural gas industries. The purpose of these systems is to provide external corrosion protection and thermal insulation. This International Standard is applicable to wet thermal insulation systems submerged in seawater. This International Standard is not applicable to thermal insulation in the annulus of a steel pipe-in-pipe system.