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 M34 New

UR M34 Scantlings of coupling flanges - 1980

UR M35 Rev7 CLN

UR M35 Alarms, remote indications and safeguards for main reciprocating internal combustion engines installed in unattended machinery spaces - Rev.7 Mar 2016

UR M36 Rev5 CLN

UR M36 Alarms and safeguards for auxiliary reciprocating internal combustion engines driving generators in unattended machinery spaces - Rev.5 Mar 2016

UR M37 Deleted

Scantlings of propeller shafts - Deleted Feb 2005

UR M38 Deleted

k-factors for different shaft design features (intermediate shafts) - Deleted Feb 2005

UR M39 Deleted

k-factors for different shaft design features (propeller shafts) - Deleted Feb 2005

UR M40 New

UR M40 Ambient conditions – temperatures - 1981

UR M41 Deleted

Superseded by UR E10 (1991)

UR M42 Rev4 CLN

UR M42 Steering gear - Rev.4 June 2011

UR M43 New

UR M43 Bridge control of propulsion machinery for unattended machinery spaces - 1982

UR M44 Rev9 Corr2 CLN

UR M44 Documents for the approval of diesel engines - Rev.9 Corr.2 Nov 2016

UR M45 Rev2 CLN

UR M45 Ventilation of machinery spaces - Rev.2 Feb 2011

UR M46 Rev1 CLN

UR M46 Ambient conditions – inclinations - Rev.1 June 2002

UR M47 New

UR M47 Bridge control of propulsion machinery for attended machinery spaces - 1983

UR M48 Deleted

Permissible limits of stresses due to torsional vibrations for intermediate, thrust and propeller shafts - Deleted Feb 2005

UR M49 Deleted

Availability of machinery - Deleted Dec 2003

UR M50 Deleted

Programme for type testing of non–mass produced i.c. engines - Deleted Feb 2015

UR M51 Rev4 CLN

UR M51 Factory Acceptance Test and Shipboard Trials of I.C. Engines - Rev.4 Feb 2015

UR M52 New

UR M52 Length of aft stern bush bearing - 1986

UR M53 Rev2 CLN

UR M53 Calculation of crankshafts for i.c. engines - Rev.2 Jan 2011

Note: UR M53 Rev 3 will come into force on 1 July 2018 and can be found in "Previous Revisions" 

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