INTERTANKO Guidance Manual for Maintenance of Tanker Structures

Number of Pages:
Published Date:
January 2008
Book Height:
300 mm
Book Width:
210 mm
0.6 kg
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This publication covers the processes of planning, inspecting and repairing steel tanker structures and any protective coatings or protection systems. The practices and procedures described can be applied to both single and double hulled tankers and recommendations apply to oil tankers of any size and configuration.

This publication outlines key considerations for tanker inspections, from preparation and execution to result analysis. It also explains the causes, types and control of tanker corrosion. Guidance is informed by, though does not fully meet, requirements of the ISM Code. The manual offers methods by which a systematic maintenance programme can be established for tanker structures.

Many regulations and publications on the survey and operation of tankers require that the owner or manager applies ‘effective maintenance’ or ‘normal maintenance’ to the ship’s structure. The documentation required for planning Class renewal surveys includes records of owners’ inspections, which are to form part of the survey report file on board. The certificates issued by some Classification Societies state that the ship is classed ‘subject to normal maintenance’. However, when asking different tanker owners what they understood by ‘normal maintenance’, all had different interpretations. It became apparent that there is no internationally accepted concept of ‘normal maintenance’.

If an owner adopts the practices laid out in this manual, they should be confident that they will meet the ISM requirement to establish procedures that ensure the ship’s structure conforms to the provisions of relevant rules and regulations.

This guide covers the maintenance of structural steel, together with its coatings or other corrosion protective system. It does not cover such items as propellers and machinery items, which are also usually given attention at routine survey intervals. Reference is made to the requirements of the ISM Code, which also requires a methodical approach to the maintenance of essential equipment and machinery. This guide, which is confined to maintenance of the structure, will by itself therefore not fully meet the ISM requirements.

Effective maintenance depends on the current condition of the structure – steel in poor condition will require more frequent inspections than steel in good condition. Furthermore, there must be a minimum standard below which the structure is unacceptable to both the Classification Society and a potential charterer.

Many owners may already have established effective means of maintaining their ships’ structures. It is certainly not proposed that these should be replaced by the methods suggested in this publication, as what works for one company may not work for another. Likewise, owners without a formal maintenance plan may find that the approach described in this manual would not work for them. We encourage all owners to adopt a methodical approach to the maintenance of ships’ structures.

Chapter 1 Introduction

Chapter 2 Regulatory Requirements for Maintenance
2.1 Introduction
2.2 International Maritime Organization Conventions
2.3 Classification Rules

Chapter 3 Review of Typical Defects
3.1 Corrosion

3.2 Structural Elements Important for Global Strength
3.3 Local Strength Issues
Chapter 4 Inspection and Maintenance Objectives
4.1 Benefits and Challenges
4.2 Vessel Age, Design, Operational Profile and Cargoes Factors affecting Scope of Inspection
Chapter 5 Inspection Programmes
5.1 The Inspection and Maintenance Plan (IMP)
5.2 Development of the Inspection and Maintenance Plan (IMP)
5.3 Inspection Preparation
5.4 Inspection Execution
5.5 Inspection Reports
5.6 Inspection Result Analysis
5.7 Acceptance Criteria
5.8 Revision of IMP

Chapter 6 Maintenance and Repair of the Hull Structure
6.1 Scope
6.2 General Requirements
6.3 Steel Repair Practice and Quality Standard

Chapter 7 Protection Against Corrosion
7.1 The Causes and Types of Corrosion
7.2 Corrosion Control
7.3 Composite Systems – Brief Overview
7.4 Specific Shipboard Applications and Conditions
7.5 Cathodic Protection Systems
7.6 IACS Guidelines for In Service Monitoring Reports
7.7 Repairs In Service – In Service Maintenance of Coating Systems
Appendix 1 Pitting Intensity Diagrams

Appendix 2 Example of an Inspection and Maintenance Plan, including Sample Report Forms for Copying

Appendix 3 Designing for Ease of Inspection and Maintenance
Appendix 4 Examples of Permanent Means of Access
Appendix 5 List of Standards in Preparation and Coating
Appendix 6 Definition of ‘Areas under Consideration’

The Tanker Structure Co-operative Forum (TSCF) is an informal technical body whose membership is voluntary and comprised of Oil Companies, Independent Owners/Operators and Classification Societies who will actively contribute to the TSCF’s Mission.

The mission of the TSCF is to advance maritime safety through improvements in the design and maintenance of tanker structures. This is achieved by sharing technical knowledge and experience in order to gain a better understanding of the safety performance of tanker structures in service. Specific topic areas of interest include corrosion, structural defects, inspection procedures, and criteria for determining renewal of damaged or corroded structure.

The TSCF is committed to sharing accumulated experience on tanker structures with the marine industry. This is achieved through prompt public release of technical manuals and information papers, and proceedings of TSCF Shipbuilder’s Meetings.


INTERTANKO (the International Association of Independent Tanker Owners) is a trade association that has served as the voice for independent tanker owners since 1970, representing the interests of its Members at national, regional and international levels.

The organisation champions an industry dedicated to support global energy networks by delivering safe, efficient and environmentally sound transport services.

INTERTANKO actively works on a wide range of operational, technical, legal and commercial issues affecting tanker owners and operators around the world. It draws on regular and direct contact with its Members and other industry stakeholders to develop and disseminate information and best practice, essential to the tanker industry.

Number of Pages:
Published Date:
January 2008
Binding Format:
Book Height:
300 mm
Book Width:
210 mm
0.6 kg