1 Principles

1.1 Application

1.1.1

The purpose of this chapter is to provide criteria for the allowable thickness diminution of ships’ hull structures.

1.1.2

The criteria apply only to ships in operation that are classed in accordance with these Rules.

1.1.3

Thickness measurement is to be used to assess ships’ hull structures against the specified renewal criteria.

1.1.4

The hull survey requirements are those given, as applicable, in the Rules and/or documents of the individual Society which incorporate:

UR Z10.2 for single side skin bulk carriers.
UR Z10.4 for double hull oil tankers.
UR Z10.5 for double side skin bulk carriers.

1.2 Corrosion allowance concept

1.2.1 Corrosion allowance

Corrosion allowance is comprised of two aspects: local and global corrosion, as defined in Ch 3, Sec 2, [1.1.2].

1.2.2 Assessment

Assessment against both local and global corrosion renewal criteria is required during the operational life of ships. Assessment against the newbuilding requirements which incorporate corrosion additions, given in Ch 3, Sec 3, and which consider all relevant loads and limit states, e.g. yielding, buckling, and fatigue is not required during the operational life of ships, provided that the measured thickness of any structural members remain greater than the renewal thickness specified in Ch 13, Sec 2, [2].

1.2.3 Steel renewal

Steel renewal is required if either the local or global corrosion allowance is exceeded.

1.3 Requirements for documentation

1.3.1 Plans

The plans to be supplied onboard the ship, as required in Ch 1, Sec 3, are to include, for each structural element, both the as-built and renewal thickness as defined in Ch 13, Sec 2. Any thickness for voluntary addition is also to be clearly indicated on the plans.

For the list of plans and information to be supplied onboard the ship, reference is made to the Rules and/or documents of the individual Society which incorporate IACS UR Z10.2, Z10.4 or Z10.5 as applicable.

1.3.2 Hull girder sectional properties

The Midship section plan to be supplied onboard the ship is to include the minimum required hull girder sectional properties, as defined in Ch 5, Sec 1, for the representative transverse sections of all cargo holds.