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 K3 Corr2 CLN

UR K3 Keyless Fitting of Propellers without Ice Strengthening - Corr.2 June 1998


Subdivision, Stability and Load Line

UR L1 Deleted


UR L2 Rev2 CLN

Intact stability - matter of class - Rev.2 Apr 2013

UR L3 Deleted

Intact stability of tankers during liquid transfer operations - Deleted May 2001

UR L4 Rev3 Corr1 CLN

UR L4 Closure of chain lockers - Rev.3 Corr.1 Aug 2011

UR L5 Rev2 Corr1 CLN

UR L5 Onboard computers for stability calculations - Adopted on Nov 2006. Implementation date 1 January 2007

Note: UR L5 Rev 3 will come into force on 1 July 2018 and can be found in "Previous Revisions" 


Machinery installations

UR M1 Deleted

Cylinder overpressure monitoring of internal combustion engines - Deleted Aug 2004

UR M2 New

UR M2 Alarm devices of internal combustion engines - 1971

UR M3 Rev5 CLN

UR M3 Speed governor and overspeed protective device - Rev.5 Feb 2006

UR M4 Deleted


UR M5 Deleted

Mass production of internal combustion engines, procedure for inspection - Deleted Feb 2015

UR M6 Deleted

Test pressures for parts of internal combustion engines 1) - Deleted Feb 2015

UR M7 Deleted

Re-categorized as “Recommendation” No. 26

UR M8 Deleted

Re-categorized as “Recommendation” No. 27

UR M9 Rev3 Corr2 CLN

UR M9 Crankcase explosion relief valves for crankcases of internal combustion engines - Rev.3 Corr.2 Sept 2007

UR M10 Rev4 CLN

UR M10 Protection of internal combustion engines against crankcase explosions - Rev.4 July 2013

UR M11 New

UR M11 Protective devices for starting air mains - 1972

UR M12 New

UR M12 Fire extinguishing systems for scavenge manifolds - 1972

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