Unified Requirements


Unified Requirements are adopted resolutions on matters directly connected to or covered by specific Rule requirements and practices of classification societies and the general philosophy on which the rules and practices of classification societies are established.

Subject to ratification by the governing body of each Member Society, Unified Requirements shall be incorporated in the Rules and practices of the Member Societies, within one year of approval by the IACS General Policy Group. 

The existence of a UR does not oblige a Member Society to issue respective Rules if it chooses not to have Rules for the type of ship or marine structure concerned.

Unified Requirements are minimum requirements. Each Member remains free to set more stringent requirements.

The technical backgrounds (development histories) of Unified Requirements since 1999 can be found by following this link.

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

UR M75 New

UR M75 Ventilation of emergency generator rooms - Feb 2016

UR M76 New

UR M76 Location of fuel tanks in cargo area on oil and chemical tankers - Apr 2016

UR M77 New

UR M77 Storage and use of SCR reductants - Sep 2016

Note: UR M77 will come into force on 1 January 2018.



UR N1 New

UR N1 One man bridge operated (OMBO) ships - 1992


Pipes and Pressure Vessels

UR P1 Rev5 CLN

UR P1 Rules for pipes - Rev.5 Nov 2001

UR P2 Rev2 CLN

UR P2 Rules for piping design, construction and testing - Rev.2 Jan 2013

UR P3 Rev4 CLN

UR P3 Air pipe closing devices - Rev.4 Jan 2016

UR P4 Rev4 CLN

UR P4 Production and application of plastic pipes on ships - Rev.4 Dec 2008


See also UI LL36 and Recommendations 4 & 5

UR P5 Deleted

Ballast water systems. Requirements on ballast water exchange at sea - Del Apr 2011

UR P6 Rev1 CLN

UR P6 Shell type exhaust gas heated economizers that may be isolated from the steam plant system - Rev.1 June 2015


Strength of Ships

UR S1 Rev7 CLN

UR S1 Requirements for Loading Conditions, Loading Manuals and Loading Instruments - Rev.7 May 2010


UR S1A Additional Requirements for Loading Conditions, Loading Manuals and Loading Instruments for Bulk Carriers, Ore Carriers and Combination Carriers - Rev.6 May 2010

UR S2 Rev1 CLN

UR S2 Definition of Ship's Length L and of Block Coefficient Cb - Rev.1 May 2010

UR S3 Rev1 CLN

UR S3 Strength of End Bulkheads of Superstructures and Deckhouses - Rev.1 May 2010

UR S4 Rev4 CLN

UR S4 Criteria for the Use of High Tensile Steel with Minimum Yield Stress of 315 N/mm2, 355 N/mmand 390 N/mm2 - Rev.4 April 2017 Clean

UR S5 Rev1 CLN

UR S5 Calculation of Midship Section Moduli for Conventional Ship for Ship's Scantlings - Rev.1 May 2010

UR S6 Rev8 CLN

UR S6 Use of Steel Grades for Various Hull Members - Ships of 90m in Length and Above - Rev.8 Dec 2015

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