IACS Unified Requirement and Unified Interpretation

This page provides the text of newly established IACS Unified Requirements (UR) and Unified Interpretations (UI) as well as their most recent revisions and corrigenda. Recent revisions and changes have been underlined for easy reference.
Texts of the IACS Unified Requirements and Unified Interpretations are made available on this page for the period of one year following the date of adoption. Texts of all current UR/UI can be found on the IACS website (http://www.iacs.org.uk).

IACS Unified Requirements

IACS Unified Requirements are the minimum class requirements shared among all IACS Member Societies. Unless an application date is specified, Unified Requirements are to be incorporated in the Rules and practices of each IACS Member Society within one year of their adoption by IACS.

IACS Unified Interpretations

IACS Unified Interpretations were created with a view to the uniform implementation of IMO conventions among all IACS Member Societies and provide interpretations of IMO Conventions which are vaguely worded or have been left to the satisfaction of each Administration.

The outlines of technical resolutions adopted by IACS are available at the links shown below.

Implementation Dates

The Implementation dates of the Unified Requirements (UR) and Unified Interpretations (UI) are shown in the "Implementation Date" column of the tables. However, as each UR / UI has its own implementation scheme, e.g. contract basis, keel laying basis, etc. please confirm the implementation dates included in the texts.

Unified Requirements and Unified Interpretations will be incorporated into the ClassNK Rules / Guidance and apply to ships classed with ClassNK.

UR Abbreviations

A : Mooring, Anchoring and Towing C : Containers D : Mobile Offshore Drilling Units
E : Electrical Installations F : Fire Protection G : Gas Tankers
I : Polar Class K : Propellers L : Load Line
M : Machinery Installations N : Navigation P : Pipes and Pressure Vessels
S : Strength of Ships W : Materials and Welding Z : Survey and Certification

UI Abbreviations

GC : IGC Code / GC Code HSC : HSC Code LL : Load Line
MPC : MARPOL PASSUB : Passenger Submersible Craft
SC : SOLAS TM : Tonnage Measurement

IACS Unified Requirement

Resolution Revision Adoption Date Title Implementation Date
UR E10 Rev.8 Corr.1 Jan. 2022 Test Specification for Type Approval ---
UR D11 Rev.4 Dec. 2021 Safety features Jan. 2023
UR M60 Rev.1 Nov. 2021 Control and Safety of Gas Turbines for Marine Propulsion Use Jan. 2023
UR S6 Rev.9 Corr.2 Nov. 2021 Use of Steel Grades for Various Hull Members - Ships of 90 m in Length and Above ---
UR M66 Corr.1 22 Oct. 2021 Type Testing for Crankcase Explosion Relief Valves ---
UR M56 Corr.1 22 Oct. 2021 Marine gears – load capacity of involute parallel axis spur and helical gears ---
UR M42 Corr.1 22 Oct. 2021 Steering Gear ---
UR G1 Rev.3 Corr.2 Oct. 2021 Vessels with cargo containment system for liquefied gas ---
UR W26 Rev.2 Sep. 2021 Requirements for Welding Consumables for Aluminium Alloys 1 Jan. 2023
UR W25 Rev.6 Sep. 2021 Aluminium Alloys for Hull Construction and Marine Structure 1 Jan. 2023
UR W18 Rev.6 Sep. 2021 Anchor chain cables and accessories including chafing chain for emergency towing arrangements 1 Jan. 2023
UR W17 Rev.6 Sep. 2021 Approval of consumables for welding normal and higher strength hull structural steels 1 Jan. 2023
UR W14 Rev.3 Sep. 2021 Steel plates and wide flats with specified minimum through thickness properties (“Z” quality) 1 Jan. 2023
UR W13 Rev.7 Sep. 2021 Thickness tolerances of steel plates and wide flats 1 Jan. 2023
UR W2 Rev.3 Sep. 2021 Test specimens and mechanical testing procedures for materials 1 Jan. 2023
UR M77 Rev.3 Sep. 2021 Storage and use of SCR reductants Jul. 2022
UR A1 Rev.7 Corr.1 Sep. 2021 Anchoring Equipment ---
UR F46 New Aug. 2021 Low pressure CO2 piping system Jul. 2022
UR Z17 Rev.16 Aug. 2021 Procedural Requirements for Service Suppliers Jan. 2022
UR W33 Rev.1 Corr.1 Aug. 2021 Non-destructive testing of ship hull steel welds ---
UR Z28 Corr.1 Jun. 2021 Surveys of Watertight Cable Transits ---
UR F45 New Jun. 2021 Installation of BWMS on-board ships Jul. 2022
UR M74 Rev.2 Jun. 2021 Ballast Water Management Systems Jul. 2022
UR P3 Rev.5 Apr. 2021 Air Pipe Closing Devices Jul. 2022
UR W1 Rev.4 Apr. 2021 Material and welding for gas tankers 1 Jul. 2022
UR S6 Rev.9 Corr.1 Mar. 2021 Use of Steel Grades for Various Hull Members - Ships of 90 m in Length and Above ---
UR N1 Del. Mar. 2021 One man bridge operated (OMBO) ships ---
UR M78 Rev.1 Feb. 2021 Safety of internal Combustion Engines Supplied with Low Pressure Gas ---
UR E21 Rev.1 Feb. 2021 Requirements for uninterruptible power (UPS) units as alternative and/or transitional power Jul. 2022
UR E17 Rev.1 Feb. 2021 Generators and generator systems, having the ship’s propulsion machinery as their prime mover, not forming part of the ship’s main source of electrical power Jul. 2022
UR E11 Rev.4 Feb. 2021 Unified requirements for systems with voltages above 1 kV up to 15 kV Jul. 2022
UR E7 Rev.5 Feb. 2021 Cables Jul. 2022
UR F15 Rev.6 Feb. 2021 Reinforced thickness of ballast and cargo oil piping Jul. 2022
UR D9 Rev.4 Feb. 2021 Machinery Jul. 2022
UR D8 Rev.3 Feb. 2021 Hazardous areas Jul. 2022
UR P4 Rev.6 Feb. 2021 Production and Application of Plastic Piping Systems on Ships Jul. 2022
UR M69 Rev.1 Feb. 2021 Qualitative Failure Analysis for Propulsion and Steering on Passenger Ships Jul. 2022
UR M68 Rev.3 Feb. 2021 Dimensions of propulsion shafts and their permissible torsional vibration stresses Jul. 2022
UR M66 Rev.4 Feb. 2021 Type Testing for Crankcase Explosion Relief Valves Jul. 2022
UR M56 Rev.4 Feb. 2021 Marine gears – load capacity of involute parallel axis spur and helical gears Jul. 2022
UR M44 Rev.10 Feb. 2021 Documents for the approval of diesel engines Jul. 2022
UR M42 Rev.5 Feb. 2021 Steering Gear Jul. 2022
UR P2 --- Feb.2021 P2.12 (Rev.3) Flexible Hoses Jan. 2022
UR P2 --- Jan. 2021 P2.7.4 (Rev.10): Mechanical joints  
P2.11 (Rev.5): Type Approval of Mechanical joints  
P2.13 (Rev.1): Installation
Jul. 2022
UR M81 New Jan 2021 Safety measures against chemical treatment fluids used for exhaust gas cleaning systems and the residues which have hazardous properties Jul. 2022
UR M75 Rev.1 Jan 2021 Ventilation of emergency generator rooms Jan. 2022
UR E12 Rev.2 Dec. 2020 Electrical Equipment allowed in paint stores and in the enclosed spaces leading to paint stores Jan. 2022
UR M77 Rev.2 Dec. 2020 Storage and use of SCR reductants Jan. 2022
UR E15 Rev.4 Dec. 2020 Electrical Services Required to be Operable Under Fire Conditions and Fire Resistant Cables Jan. 2022
UR E13 Rev.3 Dec. 2020 Test requirements for Rotating Machines Jan. 2022
UR Z7 Rev.28 Corr.1 Dec. 2020 Hull Classification Surveys ---
UR S11 Rev.10 Dec. 2020 Longitudinal Strength Standard 1 Jan. 2022
UR F7 Rev.3 Corr.1 Nov. 2020 Portable instruments for measuring oxygen and flammable vapour concentrations ---
UR Z28 New Oct. 2020 Surveys of Watertight Cable Transits 1 Jul. 2021
UR Z23 Rev.7 Oct. 2020 Hull Survey for New Construction 1 Jul. 2021
UR Z17 Rev.15 Oct. 2020 Procedural Requirements for Service Suppliers 1 Jul. 2021
UR W27 Corr.1 Sep. 2020 Cast Steel Propellers ---
UR A2 Rev.5 Sep. 2020 Shipboard fittings and supporting hull structures associated with towing and mooring on conventional ships 1 Jan. 2022
UR A1 Rev.7 Sep. 2020 Anchoring Equipment 1 Jan. 2022
UR W32 Rev.1 Sep. 2020 Qualification scheme for welders of hull structural steels 1 Jan. 2022
UR Z1 Rev.8 Jul. 2020 Annual and intermediate classification survey coverage of IMO Resolution A.1140(31) ---
UR W27 Rev.2 Jul. 2020 Cast Steel Propellers 1 Jul. 2021
UR W24 Rev.4 Jul. 2020 Cast Copper Alloy Propellers 1 Jul. 2021
UR L5 Rev.4 Jun. 2020 Computer Software for Onboard Stability Calculations 1 Jul. 2021
UR F7 Rev.3 Jun. 2020 Portable instruments for measuring oxygen and flammable vapour concentrations 1 Jul. 2021
UR W33 Rev.1 May 2020 Non-destructive testing of ship hull steel welds 1 Jul. 2021
UR Z18 Rev. 9 Apr. 2020 Survey of Machinery Jul. 2021
UR S33 Rev.3 Feb. 2020 Requirements for Use of Extremely Thick Steel Plates in Container Ships 1 Jul. 2021
UR M79 Rev. 1 Feb. 2020 Towing winch emergency release Systems Jul. 2021


IACS Unified Interpretation

Resolution Revision Adoption Date Title Implementation Date
UI LL77 New Corr.1 Dec. 2021 Application of Load Line Requirements to Conversions of Single-hull Oil Tankers to Double-hull Oil Tankers or Bulk Carriers ---
UI LL55 Rev.1 Corr.1 Dec. 2021 Least Moulded Depth for a Ship with a Rake of Keel (Regulation 3(1)) ---
UI SC169 Rev.1 Nov. 2021 Foam systems positions of aft monitors Jan. 2023
UI SC167 Rev.1 Corr.1 Nov. 2021 Electrical distribution boards ---
UI LL15 Rev.4 Nov. 2021 Length of superstructure (Regulation 34(1) and 34(2)) Jan. 2022
UI HSC6 Rev.1 Nov. 2021 Protection of Propeller Shafts Jul. 2022
UI HSC4 Del. Nov. 2021 Ventilation Grille in Toilet Entrance Door Jul. 2022
UI HSC3 Del. Nov. 2021 Public spaces extending over 2 decks Jul. 2022
UI HSC2 Del. Nov. 2021 Classification of stairways Jul. 2022
UI HSC1 Del. Nov. 2021 Cupboard as part of the space Jul. 2022
UI SC213 Rev.5 Sep. 2021 Arrangements for remotely located survival craft Jan. 2023
UI SC159 Rev.1 Corr.1 Sep. 2021 Equivalent Protection SOLAS II-2/10.7.2 ---
UI SC154 New Corr.1 Sep. 2021 Provision of Detailed Information on Specific Cargo Hold Flooding Scenarios (SOLAS XII/9.3) ---
UI SC170 Del Aug. 2021 Low pressure CO2 systems Jul. 2022
UI SC126 Rev.2 Corr.1 Aug. 2021 Fire Protection Materials for Cargo Ships ---
UI SC146 Rev.2 Jun. 2021 Fire hose couplings and nozzles 1 Jul. 2022
UI SC295 New Jul. 2021 Interpretation of Performance Standards for Float-free Emergency Position-indicating radio beacons (EPIRBs) Operating on 406 MHz (resolution MSC.471(101)) Jul. 2022
UI SC64 Rev.2 Jun. 2021 Fire dampers in ventilation ducts 1 Jul. 2022
UI LL50 Rev.6 Jun. 2021 Protection of Crew (Load Line Convention Regulation 25(4), 26(2) and 27(7) and SOLAS II-1/3-3) 8 Jun. 2021
UI LL35 Del. Jun. 2021 Stowage of timber deck cargo on ships having timber freeboards assigned (ICLL Reg.44 and 45) ---
UI MPC11 Corr.1 Jun. 2021 Interpretation to MARPOL I/27 ---
UI SC85 Rev.2 May 2021 Ro-Ro Space 1 Jul. 2022
UI SC49 Rev.3 May 2021 Fire protection arrangements in cargo spaces 1 Jul. 2022
UI SC161 Rev.2 Apr. 2021 Timber deck cargo in the context of damage stability requirements 1 Jul. 2022
UI LL8 Rev.2 Apr. 2021 Miscellaneous openings in freeboard and superstructure decks (Regulation 18(2) & 18(3)) 1 Jul. 2022
UI FTP3 Rev.3 Apr. 2021 FIRE DOOR 1 Jan. 2022
UI SC128 Del. Apr. 2021 CO2 Discharge Time ---
UI SC225 Corr.1 Mar. 2021 The occupied volume by flooded water of a flooded space in the SOLAS Chapter II-1 (Regulation 2(14)) ---
UI SC197 Rev.2 Mar. 2021 Non-combustible cargoes (Reg.II-2/ ---
UI SC87 Rev.2 Mar. 2021 Certification of Carriage of Solid Dangerous Bulk Cargoes (Reg. II-2/19.3 and 19.4) ---
UI SC61 Del. Mar. 2021 Fixed deck foam systems ---
UI HSC5 Del. Feb. 2021 Aluminium Lube Oil Sump or Tank ---
UI SC274 Rev.1 Feb. 2021 Hazardous area classification in respect of selection of electrical equipment, cables and wiring and positioning of openings and air intakes Jul. 2022
UI SC194 Rev.1 Feb. 2021 nstallation of electrical and electronic appliances on the bridge and vicinity of the bridge Jul. 2022
UI SC180 Rev.4 Feb. 2021 Hold, ballast and dry space water level detectors and Performance Standards for Water Level Detectors on Bulk Carriers and Single Hold Cargo Ships other than Bulk Carriers (Resolution MSC.188(79)) Jul. 2022
UI SC179 Rev.3 Feb. 2021 Dewatering of forward spaces of bulk carriers Jul. 2022
UI SC79 Rev.5 Feb. 2021 Certified Safe Type Electrical Equipment for Ships Carrying Dangerous Goods Jul. 2022
UI SC70 Rev.4 Feb. 2021 Cargo tank vent systems and selection of electrical equipment Jul. 2022
UI SC57 Rev.2 Feb. 2021 Venting, purging, gas freeing and ventilation Jul. 2022
UI SC43 Rev.3 Feb. 2021 Precaution against ignition of explosive petrol and air mixture in closed vehicle spaces, closed ro-ro spaces and special category spaces Jul. 2022
UI SC42 Rev.3 Feb. 2021 Precaution against ignition of explosive petrol and air mixture in closed vehicle spaces, closed ro-ro spaces and special category spaces Jul. 2022
UI SC10 Rev.3 Feb. 2021 Precautions against shock, fire and other hazards of electrical origin Jul. 2022
UI SC1 Rev.2 Feb. 2021 Main source of electrical power Jul. 2022
UI GC37 New Feb. 2021 Suitable Pressure Relief System for Air Inlet, Scavenge Spaces, Exhaust System and Crank Case Jul. 2021
UI GC36 New Feb. 2021 Oxygen Deficiency Monitoring Equipment in a Nitrogen Generator Room Area Jul. 2021
UI GC35 New Feb. 2021 Inhibition of Cargo Pump Operation and Opening of Manifold ESD valves with Level Alarms Overridden Jul. 2021
UI GC34 New Feb. 2021 Cargo Filters Jul. 2021
UI GC33 New Feb. 2021 Cargo Sampling Jul. 2021
UI GC32 New Feb. 2021 Outer Duct in Gas Fuel Piping Systems Jul. 2021
UI GC28 Corr.1 Feb. 2021 Guidance for sizing pressure relief systems for interbarrier spaces ---
UI SC11 Rev.1 Feb. 2021 Precautions against shock, fire and other hazards of electrical origin Jul 2022
UI LL65 Rev.3 Feb. 2021 Ships with assigned or reassigned reduced freeboards and intended to carry deck cargo 1 Jul. 2021
UI SC147 Rev.2 Feb. 2021 Watertight door closure ---
UI SC93 Rev.2 Feb. 2021 Enclosure of stern tubes on cargo ships 1 Jul. 2021
UI SC156 Rev.2 Jan. 2021 Doors in watertight bulkhead of cargo ships and passenger ships 1 Jul. 2021
UI SC63 Del. Jan. 2021 Pre-discharge alarm of fixed gas fire extinguishing system (FSS Code, Ch. ---
UI SC62 Rev.2 Dec. 2020 Inert gas systems Jan. 2022
UI FTP1 Del. Dec. 2020 Adhesives used in A or B class divisions ---
UI SC125 Rev.3 Dec. 2020 B and C Class Divisions ---
UI SC34 Del. Dec. 2020 Automatic sprinkler, fire detection and fire alarm system ---
UI LL10 Rev.2 Nov. 2020 Air pipes (Regulation 20) ---
UI SC137 Rev.1 Nov. 2020 Definition of High-Speed Craft ---
UI SC86 Del. Nov. 2020 Weather Decks ---
UI SC17 Rev.3 Nov. 2020 Definitions – Control Stations ---
UI SC117 Del. Sep. 2020 Fire detection system with remotely and individually identifiable detectors ---
UI MPC20 Corr. 1 Jul. 2020 Annex VI of MARPOL 73/78 Regulation and 13.2.2 ---
UI MPC101 Corr.1 Sep. 2020 Supplement to the International Air Pollution Prevention (IAPP) Certificate – Section 2.3 ---
UI GC31 New Jun. 2020 Discharge test of dry chemical powder fire-extinguishing systems 1 Jan. 2021
UI MPC115 Corr. 1 May 2020 2017 Guidelines Addressing Additional Aspects of the NOx Technical Code 2008 with regard to Particular Requirements related to Marine Diesel Engines Fitted With Selective Catalytic Reduction (SCR) Systems ---
UI SC182 Del. Apr. 2020 Bulk carriers not complying with SOLAS XII/9 as of 1 January 2004 ---
UI GC22 Rev.1 Apr. 2020 Water spray system 1 Jan. 2021
UI GC30 New Apr. 2020 Emergency fire pump Jan. 2021
UI SC292 New Feb. 2020 Ships intended to operate in low air temperature in Polar waters - Survival craft and rescue boat communications capabilities 1 Jul. 2021
UI SC293 New Feb. 2020 Lifebuoy Arrangements for Means of Embarkation/Disembarkation Jul. 2020
UI SC294 New Feb. 2020 Fire integrity of the division between engine room and urea or sodium hydroxide solution tank installation spaces Jul. 2020
UI SC291 New Jan. 2020 Safe Type requirements for twoway portable radiotelephone apparatus for fire-fighter's communication 1 Jul. 2020
UI SC207 Corr.2 Jan. 2020 SOLAS XII/5 in terms of Structural Strength of Bulk Carriers in case of Accidental Hold Flooding ---
UI MPC32 Rev. 1 Jan. 2020 Technical Code on Control of Emission of Nitrogen Oxides from Marine Diesel Engines Jul. 2020
UI SC242 Rev. 2 Jan. 2020 Arrangements for steering capability and function on ships fitted with propulsion and steering systems other than traditional arrangements for a ship’s directional control 1 Jul. 2020