A dramatic increase in the size of the world’s double hull oil tanker population, expected over the next decade, has prompted the International Association of Classification Societies (IACS) to produce harmonised hull survey procedures for such ships. The new survey procedures build upon the experience gained in the implementation of the Enhanced Survey Programmes for different types of ships, taking into account the particular structural configuration of double hull oil tankers.

The procedures are set out in a new IACS Unified Requirement (UR Z10.4: Hull Surveys of Double Hull Tankers). The new provisions were adopted in December 2001 by the IACS Council, for submission to the International Maritime Organization (IMO). The UR will be considered by the IMO’s Subcommittee on Ship Design and Equipment, when it meets in March. IACS Permanent Secretary Robin Bradley says: “The challenge is to take account of lessons relating to the construction and operation of single hull tankers and, secondly, to identify any additional measures required for double hull ships. The new IACS Unified Requirement makes a major contribution to the IMO work, as it deals with core elements of the double hull survey programme. There are important new issues raised by the large-scale introduction of double hull ships.

They tend to focus on the double hull space, more complex structures, corrosion issues and safety concerns relating to the work environment within the space. In a substantial step forward, we have provided the IMO with a harmonised approach to the hull survey of an entirely new generation of tankers.”

UR Z10.4 is now freely available at the IACS web site: www.iacs.org.uk, under “Technical”.