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 SC204 New

UI SC204 Storage of fire-extinguishing media forward the cargo holds (SOLAS regulation II-2/10.4.3. and FSS Code paragraph, Chapter 5) - April 2006

UI SC205 New

UI SC205 Portable fire-fighting appliances in cargo holds loaded with vehicles with fuel in their tanks (Regulation II-2/20.6.2) - May 2006

UI SC207 Corr1 CLN

UI SC207 SOLAS XII/5 in terms of Structural Strength of Bulk Carriers in case of Accidental Hold Flooding (SOLAS regulation XII/5) - Corr.1 Oct 2007

UI SC208 Corr2 CLN

UI SC208 SOLAS XII/6.5.1 in terms of protection of cargo holds from loading/discharge equipment (SOLAS regulation XII/6.5.1 and SLS.14/Circ.250) - Corr.2 June 2009

UI SC209 New

UI SC209 SOLAS XII/6.5.3 in terms of redundancy of stiffening structural members for vessels not designed according to CSR for Bulk Carriers (SOLAS regulation XII/6.5.3 and SLS.14/Circ.250) - June 2006

UI SC210 New

UI SC210 Double-side skin construction on bulk carriers (regulations XII/1.4 and XII/6.2) - June 2006

UI SC211 Corr1 CLN

UI SC211 Protection of fuel oil (Regulations II-2/3.6 and - Corr.1 Oct 2007

UI SC212 Corr2 CLN

UI SC212 Shipboard fittings and supporting hull structures associated with towing and mooring on conventional vessels (SOLAS Reg. II-1/3-8) - Corr.2 Oct 2007

UI SC213 Rev4 CLN

UI SC213 Arrangements for remotely located survival craft (SOLAS Regulations III/31.1.4, III/, III/11.4, III/11.7, III/13.1.3, III/16.7 and LSA Code paragraph - Rev.4 November 2016 Clean

UI SC214 New

UI SC214 Portions of open decks utilized for the storage of gas bottles Regulation II-2/4.3 Arrangements for gaseous fuel for domestic purposes - July 2006

UI SC215 Corr1 CLN

UI SC215 Embarkation Ladder Regulation - Corr.1 Oct 2007

UI SC216 Deleted

UI SC216 FSS Code – Water-based fire-extinguishing systems Withdrawn August 2008 until conclusion of IMO FP52 CG becomes available. 

UI SC217 Corr1 CLN

UI SC217 Nozzles installation for fixed water based local application fire-fighting systems for use in category A machinery spaces (MSC/Circ 913) - Corr.1 Sept 2007

UI SC218 New

UI SC218 Fire Testing of Equivalent Water-Based Fire Extinguishing Systems (IMO MSC/Circ.1165, Appendix B, 4.5.1) Regulation (IMO MSC/Circ.1165, Appendix B, 4.5.1) - October 2007

UI SC219 New

UI SC219 Fire Testing of Equivalent Water-Based Fire Extinguishing Systems (IMO MSC/Circ.1165, Appendix B, - Oct 2007

UI SC220 Rev1 Corr2 CLN

UI SC220 Rev.1 Corr.2 March 2017 Clean

Change of title: Special requirements for ro-ro passenger ships

UI SC221 Deleted

Deleted September 2017

UI SC222 Deleted

UI SC222 Stripe coats and salt measurement Withdrawn from 1 July 2008. Contents incorporated into UI SC 223 (NEW, June 2008).

UI SC223 Rev3 Corr1 CLN

UI SC223 For Application of SOLAS Regulation II-1/3-2 Performance Standard for Protective Coatings (PSPC) for Dedicated Seawater Ballast Tanks in All Types of Ships and Double-side Skin Spaces of Bulk Carriers, adopted by Resolution MSC.215(82) - Rev.3 Corr.1 October 2014 Clean

UI SC224 New

UI SC224 Measurement of Distances - August 2008

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