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IACS Publishes Recommendation 197 on hull structural steels up to 100mm thickness

27 March 2026 – The International Association of Classification Societies (IACS) has published a new recommendation, Rec.197 that complements the existing requirements of IACS Unified Requirement W11, currently addressing hull structural steels up to 100 mm thickness.

With the increasing scale of modern ships and offshore structures, the use of thicker steel plates has become more prevalent in critical structural regions (e.g. deck stringers, sheer strakes, hatch side coamings and other highly stressed structural members). The Recommendation therefore provides harmonised guidance for steels with thicknesses greater than 100 mm and up to 200 mm, reflecting both evolving industry practice and the accumulated experience of IACS Member Societies.

Scope of application

The Recommendation applies to:

  • normal and higher strength hull structural steels;
  • steel plates and wide flats;
  • thickness range greater than 100 mm and up to 200 mm.

For thicknesses exceeding 200 mm, individual assessment by the Classification Society remains required.

 

Harmonised technical framework for thick structural steels

The Recommendation establishes a harmonised technical framework within IACS covering the main requirements applicable to thick hull structural steels, including:

  • manufacturing processes and approval of steelmaking facilities;
  • acceptable delivery conditions (normalized, controlled rolled, thermo-mechanically controlled processed (TMCP), and quenched and tempered steels);
  • chemical composition and carbon equivalent limits;
  • mechanical properties and impact toughness requirements.

 

Toughness requirements and brittle fracture considerations

A key technical aspect of the Recommendation concerns the specification of impact toughness requirements for thick hull structural steels.

As the thickness of structural steel increases, the potential consequences of brittle fracture become more significant for hull structural integrity. The minimum impact energy requirements have therefore been established on the basis of fracture-mechanics-based considerations linking structural thickness, design temperature and material toughness.

The resulting toughness criteria were further evaluated through comparison with recognised fracture mechanics assessment methodologies, confirming the technical consistency of the adopted requirements.

 

Testing methodology

The Recommendation also clarifies the testing and sampling arrangements applicable to thick steel products, including:

  • tensile testing with specimens located at approximately quarter thickness;
  • impact testing generally performed at quarter thickness locations;
  • the possibility, subject to agreement with the Classification Society, to use impact specimens taken at mid-thickness with appropriate acceptance criteria.

 

Relevance for industry

This Recommendation is expected to be of particular interest to:

  • ship designers and shipbuilders involved in large vessels and heavily loaded hull structures;
  • steel manufacturers producing thick plate products for marine structural applications;
  • projects involving large structural members or high design stresses in primary hull structures.

By providing harmonised guidance across IACS Member Societies, the Recommendation supports the safe and consistent application of thick hull structural steels in modern ship construction.

 

Ajay Kumar, IACS GPG Chair, commented

“The increased scale of modern ships and offshore structures has resulted in greater use of thicker steel plates, and the publication of Rec. 197 is an important step forward in providing valuable guidance for ship designers, builders, and steel manufacturers. Drawing on the collective expertise and experience of IACS Member Societies, this new recommendation will help ensuring a harmonized technical framework for hull structural steels up to 200mm, which in turn will enhance safety.”

 

Ends/

 

Contact: Robert Ashdown, IACS Secretary General

E: robertashdown@iacs.org.uk T: +44 (0) 20 7976 0660

International Association of Classification Societies

Secretariat 4 Matthew Parker Street, London, England SW1H 9NP

E: secretariat@iacs.org.uk

T: +44 (0)20 7976 0660

 

Notes to Editors:

  • Dedicated to safe ships and clean seas, the International Association of Classification Societies (IACS) makes a unique contribution to maritime safety and regulation through technical support, compliance verification and research and development. More than 90% of the world’s cargo carrying tonnage is covered by the classification design, construction and through-life compliance Rules and standards set by the twelve Member Societies of IACS.
  • More information about IACS can be found by visiting iacs.org.uk and in our Annual Review available online at http://www.iacs.org.uk/about/iacs-annual-review/

IACS 2025 Annual Review highlights the role of class in driving progress on maritime safety and innovation

IACS’s 2025 Annual Review explores the work of IACS and its classification society Members during 2025 in leading the development of technical requirements and guidance to support global shipping

30 March 2026 – IACS, the membership organisation for the world’s leading classification societies, has published its 2025 Annual Review, which showcases the central role played by IACS and its Members in supporting safety standards and driving technical innovation in the maritime industry.

The report identifies many areas of progress, including IACS’s ongoing role in supporting industry  decarbonisation objectives and the IMO’s efforts to balance its environmental ambitions with safety. Through it’s Safe Decarbonisation Panel, IACS is supporting progress in respect of a number of alternative fuels, whilst remaining neutral on any preferred option. This includes the development of Resolutions on the safe use of alternative fuels which underpin IMO regulations, or the classification rules of each IACS Member.

IACS’s work on maritime digitalisation is also highlighted in the Annual Review. Through the Safe Digital Transformation Panel, IACS has identified and focused work on several priorities, including data quality, cybersecurity and predictive maintenance. IACS has developed Unified Requirements on cyber resilience of new ships and Recommendations for existing vessels, establishing a minimum set of cybersecurity controls as part of safety management systems. IACS has also contributed to the innovative application of digital technologies in other areas of classification activity, such as the use of 3D models for the technical review of hull design, structural strength and integrity.

The report also discusses IACS’s extensive and ongoing programme of engagement with wider industry – including intergovernmental bodies, industry associations, and international standards bodies, with flag States and port State Authorities around the world, and most significantly, with the IMO, where IACS works closely with the Secretariat and Member States. In 2025, IACS and its Members authored 37 independent submissions to IMO, plus a further 20 co-sponsored papers.

A further focus for IACS is enhancing standards of surveying excellence and meeting the evolving expectations of classification societies at a time of industry transformation, as explained by Robert Ashdown, IACS Secretary General:

 “Over the past year, the collective work of the IACS membership has again illustrated how class can contribute uniquely to maritime safety and environmental protection, while embracing the opportunities and challenges presented by emerging technologies and fuels.

 “As classification societies move beyond being simply custodians of compliance to being strategic partners in maritime transformation, IACS is supporting this evolution in its Members’ businesses to meet the expectations of regulators and the industry. This not only encompasses the traditional activities of design, construction and survey verification, but also assists their roles as active enablers of transformation in the face of digitalisation, decarbonisation and new technologies.”

2025 saw progress on the important issue of surveyor safety, Led by the work of IACS’s Expert Group on Safety of Surveyors (EG SoS). This included new Recommendations on safety standards at work for surveyors and confined space safe practice. Together, these measures deliver a consolidated approach to surveyor safety that aligns IACS with ISO 45001 principles, IMO instruments and industry best practices, and that advance a culture of safety through all classification activities.

The Review explores many other areas of technical and safety progress where IACS has made a significant contribution. These include the development of the goal-based IMO Maritime Autonomous Surface Ship (MASS) Code, and the multi-year programme to modernise the IACS Common Structural Rules (CSR). The Review also highlights the work of IACS to address fires in ship machinery spaces by reinforcing fire safety standards, the publication of updated welding high heat input welding requirements for marine and offshore structures.

In 2025, IACS published 78 new or revised Unified Requirements, Procedural Requirements, Unified Interpretations, and Recommendations for implementation by its Members, and the Annual Review provides a full list of these, as well as those which have been withdrawn. It also includes the ‘Class Report 2025’, which contains data on the global IACS fleet, broken down by the 12 IACS Members.

The 2025 Annual Review is available for download at the IACS website at https://iacs.org.uk/about-us/annual-review. Hard copies are also available on request from the IACS Secretariat at secretariat@iacs.org.uk.

 

ENDS

 

Notes to Editors

For further information, please contact: IACS@blue-comms.com

 About IACS

Dedicated to safe ships and clean seas, the International Association of Classification Societies (IACS) makes a unique contribution to maritime safety and regulation through technical support, compliance verification and research and development. More than 90% of the world’s cargo carrying tonnage is covered by the classification design, construction and through-life compliance Rules and standards set by the twelve Member Societies of IACS.

More information about IACS can be found by visiting www.iacs.org.uk and in our Annual Review available online at https://iacs.org.uk/about-us/annual-review.

IACS PARTICIPATION AT MEPC 84

In demonstrating its ongoing commitment to supporting the work of the International Maritime Organization (IMO), and within its remit as the Organization’s principal technical advisor, IACS will actively participate in the forthcoming 84th session of Marine Environment Protection Committee (MEPC 84) which will meet from 27 April to 1 May 2026.

Noting the work IACS Members undertake as recognized organizations of IMO Member States, verifying compliance of ships with IMO agreed requirements, and with a view to achieving clarity for all parties, IACS has submitted the following documents:

MEPC 84/6/7 proposes amendments to the 2022 Guidelines for the development and management of the IMO Ship Fuel Oil Consumption Database (resolution MEPC.349(78)). The proposals aim to remove a potential inconsistency (and a risk) in the application of the anonymization, and to ensure consistency with the draft amendments to regulation 27 of MARPOL Annex VI.

MEPC 84/6/14 proposes amendments to the 2022 Guidelines on the method of calculation of the attained Energy Efficiency Design Index (EEDI) for new ships (resolution MEPC.364(79)) and the 2022 Guidelines on survey and certification of the Energy Efficiency Design Index (EEDI) (resolution MEPC.365(79)), taking into account the increased use of methanol dual-fuel engines on ships.

MEPC 84/10/2 comments on the draft amendments to the NOx Technical Code 2008. In particular, the document addresses the uniform implementation of provisions in certifying engines that operate non-carbon containing fuels or mixtures of carbon-containing and non-carbon-containing fuels.

Any enquiries on the above should be sent to Mr Konstantin Petrov, IACS Accredited Representative to IMO, at arimo@iacs.org.uk

IACS publishes Recommendation on Onboard Lifting Appliances

22 April 2026 – IACS, the membership organisation for the world’s leading classification societies, has published a Recommendation to improve safety standards for lifting appliances, in line with SOLAS regulations covering both new and existing lifting appliances.

Lifting appliances play a vital role in cargo handling and ship operations, yet their limited structural redundancy has long posed safety risks for crews and vessels. To address these hazards, the International Maritime Organization (IMO) has introduced new mandatory requirements for the design, construction, installation, testing, examination, marking, maintenance, inspection and operation of lifting appliances under the SOLAS Convention. These regulations entered into force on 1 January 2026 and aim to prevent failures that have previously resulted in fatalities, injuries, lifting appliances loss and ship damage.

The new SOLAS regulations apply to all new lifting appliances installed on or after 1 January 2026, and to existing lifting appliances and associated loose gear no later than the first renewal survey on or after that date. Regulation II-1/3-13 introduces requirements for classification of standard design and construction, periodic load testing and thorough examinations for both new and existing lifting appliances.

IACS strongly supports the inclusion of lifting appliances within the SOLAS Convention, recognising the substantial improvement this brings to maritime safety. In support of this new framework and to facilitate consistent global implementation of the SOLAS regulations, IACS has developed a comprehensive Recommendation on Onboard Lifting Appliances, providing guidance on, for example:

  • Distinguishing between new and existing lifting appliances;
  • Application of SOLAS regulation II-1/3-13 to lifting appliances with a safe working load below 1000 kg;
  • What information is the prerequisite to account for existing lifting appliances and loose gear that enters into the SOLAS regime (certificates, load test and thorough examination);
  • Examples of loose gear to which the application of SOLAS regulation II-1/3-13 should be considered and for where it should not and the documentation required for the consideration of existing loose gear in the SOLAS regulation II-1/3-13 regime;
  • Appliances serving as launching appliances for survival craft or rescue boats and as lifting appliances for cargo handling (dual use);
  • Necessary documentation and certification procedure for equipment with modification or alteration of major character;
  • Survey and testing regimes and timeframes, including alignment with the Harmonized System of Survey and Certification (HSSC);
  • Date of the initial verification of compliance with SOLAS regulation II-1/3-13 regime.

Commenting on the new Regulation, Robert Ashdown, IACS Secretary General, said:

“As the new SOLAS requirements take effect, close cooperation among classification societies, Flag State Administrations and industry stakeholders will be essential. IACS remains committed to providing clear, practical guidance and supporting the maritime sector in achieving safer lifting operations worldwide, and the new IACS Recommendation will help ensure the consistent application of the SOLAS rules, reduce the risks to crew and vessels of lifting appliance failure.”

The new IACS Recommendation builds on the SOLAS regulations by providing detailed reference to relevant aspects of SOLAS and the scenarios relating to the various modes of application of lifting appliances. It also clarifies the classification of lifting appliances to which SOLAS II-1/3-13 applies, as well as clear examples of lifting appliances to which SOLAS II-1 Reg 3-13 May or may not apply.

The Recommendation follows on from prior work by IACS to enhance lifting appliance safety. IACS had already issued a new Unified Interpretation (UI SC310, July 2025) – also published by IMO as MSC.1/Circ.1696 – which introduces a ‘factual statement’ template confirming testing and examination of non-certified existing lifting appliances in accordance with MSC.1/Circ.1663.

The new IACS Recommendations builds on this by suggesting the use of ‘Factual Statements’ and highlights the critical importance of the nomination of a Safe Working Load (to the satisfaction of the Administration), in line with UI SC 310 (MSC.1/Circ.1696), for existing lifting appliances without valid certificates of test and thorough examination.

IACS also published Recommendation No. 191 in 2025 for lifting appliances involved in personnel handling operations.

Full details of the ‘Recommendation on Onboard Lifting Appliances’ can be found on the IACS website at here.

ENDS

 Notes to Editors

 For further information, please contact: IACS@blue-comms.com

 About IACS

Dedicated to safe ships and clean seas, the International Association of Classification Societies (IACS) makes a unique contribution to maritime safety and regulation through technical support, compliance verification and research and development. More than 90% of the world’s cargo carrying tonnage is covered by the classification design, construction and through-life compliance Rules and standards set by the twelve Member Societies of IACS.

More information about IACS can be found by visiting www.iacs.org.uk and in our Annual Review available online at https://iacs.org.uk/about-us/annual-review.

IACS PARTICIPATION AT MSC 111

In demonstrating its ongoing commitment to supporting the work of the International Maritime Organization (IMO), and within its remit as the Organization’s principal technical advisor, IACS will actively participate in the forthcoming 111th session of the Maritime Safety Committee (MSC 111) which will meet from 13 May to 22 May 2026.

Noting the work IACS Members undertake as recognized organizations of IMO Member States, verifying compliance of ships with IMO agreed requirements, and with a view to achieving clarity for all parties, IACS has submitted the following documents:

MSC 111/INF.11 provides an update on the status of work undertaken to address GBS audit observations common to IACS members (as of 28 February 2026).

MSC 111/4/4 comments on document MSC 111/4/2 by the Secretariat relating to a recent stakeholder workshop to consider the goal-based ship construction standards for bulk carriers and oil tankers (GBS).

MSC 111/5/5 provides a consistency check of the draft MASS Code, based on the latest consolidated version published after the fourth Intersessional MASS Working Group (ISWG/MASS 4). It identifies areas where small editorial amendments are required and provides draft text as appropriate for certain sections to ensure consistency. Some changes are proposed to align the Code holistically with developments and decisions made during previous MASS Working Groups and Intersessional Working Groups. This document aims to support the Working Group’s progress to finalize the non-mandatory MASS Code at MSC 111.

MSC 111/5/14 provides editorial comments on the proposed forms of MASS certificates as presented in document MSC 111/5/6 by China.

MSC 111/5/15 comments on document MSC 111/5/6 by China, containing proposals for the forms of certificates for MASS. IACS submits the document with the aim of facilitating the discussion and to ensure that the format and content of the certificates and records comply with the requirements stipulated in chapter 5 and other relevant chapters of the draft MASS Code.

MSC 111/10 encourages the increased visibility of Formal Safety Assessments (FSA) in rule-making at the IMO. The proposal to enhance access to FSA reports through the IMO document portal (IMODOCS), is made to encourage more frequent use of FSA in developing regulations which target complex safety issues.

MSC 111/12/1 comments on document MSC 111/12 (Secretariat) (report of SDC 12) and the proposal to revoke MSC.1/Circ.1689 on Escape arrangements from the lower part of the machinery spaces (SOLAS regulations II-2/13.4.1 and 13.4.2). IACS proposes that in lieu of revocation, the circular is revised to provide clarity to Administrations and port State control authorities on interpretations of these SOLAS regulations.

MSC 111/14/3 seeks clarification on the draft new paragraph 4.19.1.7 of the IGC Code, which concerns the duplication of heating systems designed to protect hull structures from exposure to low temperatures of liquefied gases. It also proposes an editorial modification to avoid misinterpretation of the scope of emergency power supply requirements.

MSC 111/14/4 proposes to correct structural errors identified in the draft amendments to paragraphs 4.20.1.1 and 4.20.1.2 of the IGC Code to ensure the appropriate implementation.

MSC 111/14/5 highlights the potential design impacts of retroactive application of draft amendments to paragraphs 8.4.3.1 and 8.4.3.2 of the IGC Code concerning upstream pressure losses of pressure relief valves (PRVs). It proposes that these amendments be applied to new ships only and that the deleted sentence currently in draft paragraph 8.4.3.2 be retained to avoid unintended consequences for existing ships.

MSC 111/14/11 comments on the draft interim guidelines for the use of ammonia cargo as fuel. IACS identifies potential ambiguity arising from the repeated use of the term “ammonia cargo as fuel”. In particular, the wording of the draft interim guidelines creates uncertainty of application of the interim guidelines to gas carriers intended to carry ammonia exclusively for use as fuel, and not as cargo.

MSC 111/19 proposes a new output to amend paragraph 4.6.3.1 of the LSA Code to remove ambiguity in the requirements for colour contrasting of the safety harness with the colour of the safety harness fitted to immediately adjacent seats of free-fall lifeboats. This proposal aims to also bring clarity for the terms “seating positions” for davit-launched lifeboats and “seats” for free-fall lifeboats.

MSC 111/19/1 proposes a new output to amend paragraph 3.5.4 and table 19.1 of SOLAS regulation II-2/19 to clarify the cases where reduced ventilation rates are allowed in container cargo spaces carrying dangerous goods with a view to ensuring consistent implementation.

MSC 111/19/4 proposes a new output to review circular MSC-MEPC.3/Circ.4/Rev.1 on Revised harmonized reporting procedures – Reports required under SOLAS regulations I/21 and XI-1/6, and MARPOL, articles 8 and 12, which form the basis of reports made to the Marine Casualties and Incidents (MCI) module in the IMO Global Integrated Shipping Information System, GISIS. Reviewing the circular, which was issued in 2014, and updating its taxonomy, will enhance data quality and strengthen safety analysis.

MSC 111/21/5 comments on document MSC 111/21/4 by the Secretariat pertaining to an assessment of the development of IQARB, including proposed terms of reference for a future IMO observer to IQARB. Welcoming the establishment of IQARB, IACS agrees with the logic of appointing an IMO observer to IQARB and recognizes the importance of ensuring that the IMO observer to IQARB is entirely independent of the body it is observing.

Any enquiries on the above should be sent to Mr Konstantin Petrov, IACS Accredited Representative to IMO, at arimo@iacs.org.uk

IACS publishes results of Concentrated Inspection Campaign on onboard Emergency Power Supply

Inspections conducted on over 36,000 ships during 2025, and recommendations made to improve emergency power supply tests

5 May 2026 – IACS, the membership organisation for the world’s leading classification societies, has published the results of its Concentrated Inspection Campaign on Emergency Power Supply Tests on ships, conducted during 2025, and made a number of recommendations that will improve compliance with SOLAS requirements.

The campaign was launched in response to concerns raised by the Tokyo MoU over risks in the testing procedures, following observations raised by Port State Control officers over the reliability of ‘simulated blackout’ tests as demonstrating SOLAS compliance.

The Concentrated Inspection Campaign commenced on 1 January 2025 and ended on 31 December 2025. During this 12-month period, emergency power supply inspections were conducted on a total of 36,723 ships. No issues were identified in the vast majority of cases, but a range of deficiencies were found on 853 inspected ships (2.32%).

Based on an analysis of the data gathered during this inspection campaign, the survey panel reached a number of conclusions.

A number of critical and recurring equipment failure points were identified, including the closing quick-closing valve, control unit/circuit (PCB/relay), and Emergency Diesel Generator (EDG) starting arrangement. These failures indicate industry-wide issues with equipment maintenance, installation quality, or component durability, and directly compromise SOLAS Ch. II-1 Reg. 42/43 compliance for automatic Emergency Power Supply (EPS) activation.

The campaign also identified non-equipment deficiencies, the most notable of which is the lack of controlled blackout test procedures in company and shipboard Safety Management Systems (SMS). This is contrary to SOLAS Ch. II-1 Reg. 42.7/43.7 (periodic full system testing). Simulated blackout tests are widely used, but do not test the actual circuit paths required for real blackouts, which gives ships’ engineers a false sense of readiness of the ship’s emergency systems.

From an operational perspective, the campaign also identified crew unfamiliarity with Emergency Diesel Generator (EDG) operation and the mis-selection of starting switch modes. This highlighted the role of human error as a contributor to malfunctions during emergencies. Including gaps in crew training, competency, and safety culture.

The report also set out a number of recommendations

  • During ISM audits, focus should be on ensuring that a procedure exists in the necessary detail for conducting a controlled blackout test for emergency diesel generators and may pay more attention to whether the testing arrangements and procedures for emergency diesel generators adequately demonstrate the functionality of the emergency power supply system as a whole, including by means of controlled blackout testing where appropriate
  • IACS will consider a further analysis to clarify the inspection and testing cycles and requirements for high-frequency malfunctional components such as quick-closing valves, control units and starting devices.
  • IACS will consider further studies to standardize the design standards for emergency generator simulation tests to ensure that the design complies with the requirements of

Commenting on the findings of the campaign, Robert Ashdown, IACS Secretary General, said:

“We are grateful to our members for their close engagement and support for this Concentrated Inspection Campaign, which was prompted by a warning from the Tokyo MoU about potential risks in the testing of emergency power systems that may not meet SOLAS standards. Their rapid response has enabled us to conduct over 36,000 inspections in this 12-month period. This in turn has delivered robust and detailed data insights into this critical issue across the global fleet.”

“Over 97% of ships inspected had no deficiencies, but a range of issues were identified in the remaining cases. Based on these findings, the IACS panel set out a number of conclusions and recommendations on inspection and testing procedures, requirements, and crew training for emergency power system tests. These will play an important role in ensuring that emergency systems operate as intended, comply with SOLAS requirements, and enhance safety at sea.”

In the 853 inspections where deficiencies were found, the deficiencies are categorised as follows:

  • Malfunction of control unit/circuit: 16%
  • Malfunctioned Air Circuit Breaker (ACB): 12%
  • Mis-selection of engine starting selection switch mode in emergency generator room: 12%
  • Closing quick-closing valve: 22%
  • Malfunction of starting arrangement: 14%
  • Malfunction of engine: 8%
  • No power supply to the services essential for safety in an emergency: 10%
  • Other: 7%

The consolidated report of the concentrated inspection campaign is available on the IACS website at here.

 

ENDS

Notes to Editors

For further information, please contact: IACS@blue-comms.com

About IACS

Dedicated to safe ships and clean seas, the International Association of Classification Societies (IACS) makes a unique contribution to maritime safety and regulation through technical support, compliance verification and research and development. More than 90% of the world’s cargo carrying tonnage is covered by the classification design, construction and through-life compliance Rules and standards set by the twelve Member Societies of IACS.

More information about IACS can be found by visiting www.iacs.org.uk and in our Annual Review available online at https://iacs.org.uk/about-us/annual-review.