Coating Maintenance - Guidelines for Coating Maintenance & Repairs for Ballast Tanks and Combined Cargo/Ballast Tanks on Oil Tankers (IACS Rec 87)

This publication is a guide to the survey, maintenance and repair of coatings in ballast tanks or combined cargo/ballast tanks. It has been developed to assist with maintaining, or restoring, good coating condition.

This edition supersedes:

• Guidelines for Coatings Maintenance and Repair
• Guidelines for Coatings Maintenance and Repair (Pocket Book).

1.1 Application

These Guidelines focus on survey, maintenance and repair procedures of coatings.

Chapter 2 is primarily intended for Class surveyors in assessing the coating condition. Chapter 3 is primarily intended for Owners, Yards and Flag Administrations in connection with inspection, maintenance and/or repair schemes.

These Guidelines deal with ballast tanks and combined cargo/ballast tanks herein referred to as "ballast tanks" on tankers in service. They only cover maintenance and repair of coatings. Corrosion prevention systems other than coating are not covered, nor is the design, installation and maintenance of anodes, for such topics, clarification should be obtained by the Classification Society concerned. Steel repair is further described in other relevant IACS Rec. No. 47 "Shipbuilding and Repair Quality Standard".

The intention with maintenance and repair in this context is to either:

• maintain GOOD coating condition, or
• restore GOOD coating condition if the coating is found in FAIR or POOR condition.

These Guidelines have been developed using the best information currently available, and considering that maintenance and repair may take place:

• In dry dock
• afloat at yard
• on voyage (Riding crew).

They are intended only as guidance in support of the sound judgement of surveyors. Should there be any doubt with regard to interpretation or validity in connection with the use of these Guidelines, clarification should be obtained from the Classification Society concerned.

1.2 Class survey requirements

The coating system in ballast tanks is to be examined in connection with:

• Intermediate Surveys for tankers exceeding 5 years of age
• special Surveys for all tankers.

The condition of the coating in ballast tanks is assigned and categorised as GOOD, FAIR or POOR based on visual inspection and estimated percentage of areas with coating failure and rusty surfaces. (see Table II in Chapter 2).

The ballast tank will be subject to Annual Survey when, during an Intermediate or Special Survey, as applicable, it is found with:

• no protective coating from the time of construction, or
• a soft coating, or
• Substantial Corrosion or
• protective coating in less than GOOD condition and the protective coating is not repaired to the satisfaction of the Surveyor, or
• a common plane boundary with a cargo tank with any means of heating, regardless of whether the heating system is in use and regardless of the condition of the coating. (Only single hull oil tanker as defined in UR Z10.1).

Thickness measurements to the same extent as the previous Special Survey are mandatory requirements of Intermediate Surveys for tankers exceeding 10 years of age. However, the surveyor may request thickness measurements as a result of his examination of the ballast tanks, if he considers it necessary, on a tanker of any age. If the results of these thickness measurements indicate that Substantial Corrosion is present, the extent of thickness measurements is to be increased.

Areas of Substantial Corrosion identified at previous Special, Intermediate or Annual Surveys are to have thickness measurements taken at Annual Surveys regardless of the coating condition. Substantial Corrosion is an extent of corrosion such that assessment of corrosion pattern indicates wastage in excess of 75% of allowable margins, but within acceptable limits. When wastage exceeds acceptable limit, repair such as renewal of the hull structural members is to be carried out.

Further details on the scope and extent of annual surveys are provided in:

• IACS UR Z10.1, Z10.3 and Z10.4
• the instruction to surveyor of individual Classification Societies.

A record of Substantial Corrosion should still be made even if the owner elects to coat the area and arrest further corrosion.

For areas in ballast tanks where coatings are found to be in a GOOD condition, the extent of thickness measurements may be specially considered by the Classification Society.

Special Surveys are to be carried out at 5 years intervals to renew the Class Certificate. Intermediate Survey is to be held at or between either the 2nd or 3rd Annual Survey. Annual Surveys are to be held within 3 months before or after anniversary date.

Chapter 1: Introduction

1.1 Application

1.2 Class survey requirements

Chapter 2: Coating Conditions

2.1 Good, fair, poor

2.2 Areas under consideration

Chapter 3: Coating Maintenance and Repairs

3.1 Process considerations

3.2 Principles for maintenance and repairs

References

Appendix

A. Failures

B. Corrosion prevention

C. Surface preparation methods

D. Pictorial ISO standards

E. Definitions and description of terms

F. Pertinent Standard

G. Tables comparing commonly used standards

H1. Examples of assessment of coating conditions

H2. Library of pictures

I. Examples of how to report coating conditions with respect to areas under consideration

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