As the ship grows older, the scope of this inspection widens to cover those areas
of the ship which are vulnerable to ageing. For example, as oil tankers grow older
the area of the deck plate is subject to tests for corrosion increases. To avoid the
inconvenience and time out of service the classification societies allow a continuous
survey. Under this arrangement the ship is subject to a programme of rolling
inspections, with one-fifth of the ship being covered each year.
As more governments have acquired flag state regulatory authority over the last
30 years, the role of classification societies as representatives of governments has
increased. The most common authorizations are in connection with tonnage
measurement and loadlines; SOLAS, MARPOL and IMO standards on the
transportation of dangerous goods. In carrying out statutory work, the classification
society applies the standards relevant to the country of registry.