Stricter Oversight on Thickness Measurement Firms – MSC.553(108)

Stricter Oversight on Thickness Measurement Firms

The quality and reliability of hull thickness measurements are an important part of the structural survey process for applicable bulk carriers and oil tankers subject to the International Code on the Enhanced Programme of Inspections during Surveys of Bulk Carriers and Oil Tankers, 2011 (2011 ESP Code).

From 1 January 2026, amendments adopted by the International Maritime Organization through MSC.553(108) strengthen the procedures for the approval and certification of firms engaged in thickness measurement of hull structures.

The amendments specifically provide for the Administration to audit the thickness measurement firm after satisfactory review of the firm's submitted documentation, in order to ascertain that the firm is properly organized and managed in accordance with the submitted documents and is capable of conducting thickness measurements of ship hull structures.

This strengthens the overall oversight framework surrounding thickness measurement services and supports greater confidence in the structural information used during applicable enhanced surveys.

MSC.553(108) and the 2011 ESP Code

MSC.553(108) is an IMO resolution adopted by the Maritime Safety Committee on 23 May 2024. It contains amendments to the 2011 ESP Code concerning the procedures for approval and certification of firms engaged in thickness measurement of hull structures.

The amendments entered into force on 1 January 2026. They address the Administration's role in auditing firms that carry out thickness measurements under the applicable enhanced survey framework.

The purpose is not to create a new independent class-surveyor audit authority. Rather, the amendment strengthens the Administration's ability to verify that an approved or certified thickness measurement firm is appropriately organized, managed and capable of performing the required work.

What Changed for Thickness Measurement Firms?

The amended procedures place clear emphasis on the ability of the thickness measurement firm to demonstrate that it is properly organized, appropriately managed and capable of conducting thickness measurements of hull structures.

Following satisfactory review of the documentation submitted by the firm, the Administration shall audit the firm to verify that its actual organization and management are consistent with the submitted documentation and that the firm is capable of performing hull structural thickness measurements.

Key Areas of Oversight

• Organization and management: the firm should be properly organized and managed in accordance with the documentation submitted for approval or certification.
• Technical capability: the firm should be capable of conducting thickness measurements of ship hull structures within the applicable scope.
• Personnel competence: personnel carrying out measurements should possess the appropriate knowledge, training, experience and qualifications required by the applicable approval or certification framework.
• Measurement procedures: the firm should operate according to documented procedures appropriate for the thickness measurement work undertaken.
• Equipment: measurement equipment should be suitable for the intended work and maintained in appropriate condition.
• Calibration and verification: appropriate arrangements should be maintained to support the reliability and accuracy of measurement equipment.
• Quality control: measurement activities and results should be subject to appropriate controls consistent with the firm's approved or certified arrangements.
• Measurement records and reporting: results should be properly recorded, identified and reported so that they can be used as part of the applicable structural survey process.

Which Ships Are Most Affected?

The 2011 ESP Code applies to the enhanced survey of applicable bulk carriers and oil tankers. The exact structural survey and thickness measurement requirements depend on the vessel type, construction characteristics, applicable statutory requirements and the survey being carried out.

Why Accurate Thickness Measurement Matters

Hull thickness measurements provide objective information about the remaining thickness of structural steel and help identify areas affected by corrosion, wastage, pitting, local deterioration and structural diminution.

Reliable measurement information can be used by the attending surveyor and other responsible technical parties when assessing the vessel's structural condition against the applicable requirements.

Measurement Results May Identify

• General corrosion and wastage
• Localized corrosion
• Pitting and local deterioration
• Structural diminution
• Areas approaching applicable renewal thickness
• Areas requiring further close-up examination
• Locations requiring repairs or additional technical assessment

Incomplete, inconsistent or questionable measurement data may result in additional measurements, further examination or clarification before the applicable survey can be completed.

Approval and Certification of Thickness Measurement Firms

The 2011 ESP Code contains procedures concerning the approval and certification of firms engaged in thickness measurement of hull structures.

These procedures require the firm to provide documentation describing its organization, management and technical capability. The Administration reviews the submitted information and, where the document review is satisfactory, the firm is subject to an Administration audit.

The audit is intended to ascertain that the firm is duly organized and managed in accordance with the documents submitted and is capable of conducting thickness measurement of ship hull structures.

This provides an important verification step between the firm's submitted documentation and its actual ability to perform the required technical work.

Preparation Before a Hull Thickness Measurement Survey

Proper preparation helps ensure that the measurement work can be completed efficiently and that the resulting information is suitable for the intended structural survey.

Shipowners and Managers Should Consider

• Confirming the applicable survey and thickness measurement scope with the attending classification or authorized surveyor.
• Selecting a thickness measurement firm that is approved, certified or otherwise accepted as required by the applicable Administration and recognized organization arrangements.
• Preparing relevant structural drawings and previous thickness measurement reports.
• Reviewing previous measurement results and known areas of corrosion or structural deterioration.
• Providing safe access to the structural areas requiring examination.
• Ensuring tanks, holds and other spaces are suitably prepared for the planned examination.
• Coordinating the measurement programme with the attending surveyor.
• Ensuring that measurement personnel and equipment are properly prepared for the assigned work.

Thickness Measurement Planning

A thickness measurement plan should be developed in accordance with the applicable ESP requirements and the vessel's structural history.

The planning process should identify the structural areas requiring measurement and provide sufficient information to allow the resulting data to be properly evaluated within the applicable survey process.

Measurement Equipment and Data Quality

Ultrasonic thickness measurement equipment is commonly used for ship structural examinations. The reliability of the resulting information depends on the suitability of the equipment, its condition and verification, the competence of the operator, the surface condition and the measurement technique used.

Important Technical Considerations

• Suitability of the ultrasonic thickness measurement equipment for the intended work
• Appropriate calibration and verification arrangements
• Condition and accessibility of the measurement surface
• Correct probe selection and measurement technique
• Reliable identification of measurement locations
• Accurate recording of individual readings
• Appropriate quality checks of measurement information
• Clear and traceable reporting

Where measurement results appear inconsistent with the visible condition of the structure, additional readings or further examination may be required.

Role of the Administration and Surveyor

Under the amended 2011 ESP Code procedures, the Administration has a specific role in auditing the thickness measurement firm after satisfactory review of the firm's submitted documentation.

The purpose of the Administration audit is to verify that the firm is properly organized and managed in accordance with the submitted documentation and is capable of conducting thickness measurements of hull structures.

The attending surveyor has a separate role within the applicable statutory and classification survey process. Thickness measurement results form part of the technical information available to the surveyor when assessing the structural condition of the vessel.

The measurement firm and the surveyor therefore have distinct but complementary responsibilities. The measurement firm performs the measurement work and provides the associated data, while the attending surveyor evaluates the information within the applicable survey framework.

Common Problems That Can Delay a Survey

Compliance Impact of MSC.553(108)

The significance of MSC.553(108) is the strengthening of Administration oversight of firms conducting hull structural thickness measurements under the applicable 2011 ESP Code framework.

The amendment helps close an important verification loop by allowing the Administration to audit the measurement firm and determine whether its actual organization, management and technical capability correspond with the information submitted for approval or certification.

Reliable thickness measurement information is important because structural survey decisions may depend on the data obtained from the hull structure. Effective oversight therefore supports confidence in the technical information used during applicable enhanced surveys.

The amendment should not be interpreted as creating a universal requirement that every thickness measurement firm is independently audited by every surveyor. The specific approval, certification and oversight arrangements remain subject to the applicable Administration and recognized organization framework.

Independent Technical Support for Hull Condition Assessment

PAMS Pacific Admiralty Maritime Services provides independent marine surveying and marine technical consultancy services for shipowners, operators and maritime stakeholders.

Technical support may include vessel condition assessment, review of structural survey documentation, coordination of technical inspections, evaluation of thickness measurement information and assistance with preparation for applicable statutory and classification surveys.

PAMS does not replace the responsibilities of the flag Administration, classification society or authorized surveyor. Its role is to provide independent technical consultancy and survey support within the agreed scope.