Unified Interpretations


Unified Interpretations are adopted resolutions on matters arising from implementing the requirements of IMO Conventions or Recommendations. Such adopted resolutions can involve uniform interpretations of Convention Regulations or IMO Resolutions on those matters which in the Convention are left to the satisfaction of the Administration or vaguely worded.

Interpretations are circulated to Administrations concerned or are sent to IMO for information, as appropriate.


  1. IACS, as an international Non-Governmental Organization having observer status at IMO, works in co-operation with IMO in order to endeavour that regulations developed at IMO are clear, unambiguous and can easily be applied without the need of interpretations.
  2. However, interpretations may still be needed in cases where IMO regulations contain only functional requirements, allow alternative solutions to prescriptive requirements, are left to the satisfaction of Administrations or are generally or vaguely worded.
  3. The following Unified Interpretations (UIs) have been developed by IACS to assist the unified implementation of IMO regulations falling in the above-mentioned cases. It should be noted that the development of IACS Unified Interpretations (UIs) is not aiming at introducing additional requirements but at achieving uniform application of IMO regulations.
  4. IACS UIs are to be applied by IACS Societies to ships whose flag Administrations have not issued definite instructions on the interpretation of the IMO regulations concerned, in the course of statutory certification on behalf of those flag Administrations.

The technical backgrounds (development histories) of Unified Interpretations since 2004 can be found by following this link.

A list of the IACS working groups responsible for each Unified Interpretation may be found here.

UI SC122 Rev1 Corr1 CLN

UI SC122 Corrosion Prevention in Seawater Ballast Tanks (Chapter II-1, Regulation 3-2) - Rev.1 Corr.1 Oct 2008

UI SC123 Rev3 CLN

UI SC123 Machinery Installations - Service Tank Arrangements Reg. II-1/26.11 - Rev.3 Dec 2005

UI SC124 Rev1 Corr1 CLN

UI SC124 Emergency Source of Power in Passenger and Cargo Ships Reg. II-1/42.3.4 and II-1/43.3.4 - Rev.1 Corr.1 Oct 2007

UI SC125 Rev2 Corr1 CLN

UI SC125 B and C Class Divisions (Reg. II-2/3.4 and Reg. II-2/3.10) - Rev.2 Corr.1 January 2010 Clean

UI SC126 Rev2 CLN

UI SC126 Fire Protection Materials for Cargo Ships (SOLAS regulations II-2/5.3 and 6.2) Rev.2 Nov 2005

UI SC127 Rev2 CLN

UI SC127 Paints, varnishes and other finishes (Reg. II-2/6.2) - Rev.2 November 2005

UI SC128 Rev2 CLN

UI SC128 CO2 Discharge Time (Reg. II-2/, FSS Code, Ch. 5, - Rev.2 Nov 2005

UI SC129 Rev2 CLN

UI SC129 Fire Detection in Unmanned Machinery Spaces (Reg. II-2/7.4) - Rev.2 Nov 2005

UI SC130 Rev2 CLN

UI SC130 Fire Detection and Sprinkler Systems in Refrigerated Chambers and Similar Spaces (Reg. II-2/7.5.2 and Reg. II-2/ (Reg. II-2/41-2.5 as contained in MSC24(60), FSS Code, Ch. 8, 2.1.1) - Rev.2 Nov 2005

UI SC131 Deleted

UI SC131 Liquid Cargoes for which regular foam is not effective for Fire Fighting Deleted in Nov 2005 because of SOLAS 2000 Amendments.

UI SC132 Rev4 CLN

UI SC132 Release Operation of the CO2 System FSS Code, Ch 5, (as amended by MSC.339(91)) - Rev.4 November 2013 CLN

UI SC133 New

UI SC133 Oil Mist Detector on High Speed Engines - “equivalent device” (Chapter II-1, Regulation 47.2) - May 1998

UI SC134 New

UI SC134 Essential Services and Arrangements of Sources of Power, Supply, Control and Monitoring to the different Catergories of Essential Services (SOLAS Regulations ll-1/40 & 41) - June 2002

UI SC135 Deleted

UI SC135 Escape Route or Low Location Lighting (LLL) (Chapter II-2, Regulation 28.1.10) Deleted in May 2004

UI SC136 Rev3 CLN

UI SC136 Connecting means by which the main bus bars of the main source of electrical power are normally connected (Chapter II-1, Regulation - Rev.3 Nov 2005

UI SC137 New

UI SC137 Definition of High Speed Craft (Chapter IX, Reg 1.8) - April 1998

UI SC138 New

UI SC138 Safe Access to Tanker Bows Reg. II-1/3-3.2 - May 1998

UI SC139 Deleted

UI SC139 Navigation bridge visibility (Chapter V, Regulation 22) Deleted Dec 2011

UI SC140 Rev3 CLN

UI SC140 Secondary Means of Venting Cargo Tanks Reg. II-2/ - Rev.3 January 2011 Clean

UI SC141 Deleted

UI SC141 Information on compliance with requirements for bulk carriers - "triangle" to be marked on a bulk carrier (Chapter XII, Regulation 8.3) Deleted in July 1999.

Forgotten Password

Please enter your email address here and you'll receive an email with instructions on how to reset your password.