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 W11 Rev8 CLN

UR W11 Normal and higher strength hull structural steels - Rev.8 April 2014 Clean

Note: UR W11 Rev 9 will come into force on 1 July 2018 and can be found in "Previous Revisions" 

UR W12 Deleted


UR W13 Rev5 Corr1 CLN

UR W13 Thickness tolerances of steel plates and wide flats - Rev.5 Corr.1 May 2012

UR W14 Rev2 CLN

UR W14 Steel plates and wide flats with specified minimum through thickness properties (“Z” quality) Rev.2 May 2004

UR W15 Deleted


UR W16 Rev3 CLN

UR W16 High strength steels for welded structures - Rev.3 Mar 2016 Complete Revision

UR W17 Rev4 CLN

UR W17 Approval of consumables for welding normal and higher strength hull structural steels - Rev.4 Jan 2016

UR W18 Rev5 CLN

UR W18 Anchor chain cables and accessories including chafing chain for emergency towing arrangements - Rev.5 May 2004

UR W19 Deleted

Normal and higher strength hull structural steel grades E and E36 with thicknesses above 50 up to 100 mm - superseded by W11,  - Deleted 1995 

UR W20 Deleted

Higher strength hull structural steels with a minimum yield strength of 390 N/mm2 - superseded by W11, - Deleted 1995 

UR W21 Deleted

Hull structural steels for low temperature application - superseded by W11, - Deleted 1995 

UR W22 Rev6 CLN

UR W22 Offshore mooring chain - Rev.6 June 2016

UR W23 Rev1 CLN

UR W23 Approval of welding consumables for high strength quenched and tempered steels for welded structures - Rev.1 1997

UR W24 Rev3 Corr1 CLN

UR W24 Cast copper alloy propellers - Rev. 3 Corr.1 Jan 2013

UR W25 Rev5 CLN

Aluminium alloys for hull construction and marine structure - Rev.5 June 2014

UR W26 Rev1 CLN

UR W26 Requirements for welding consumables for aluminium alloys - Rev.1 June 2005

UR W27 Rev1 CLN

UR W27 Cast steel propellers - Rev.1 May 2004

UR W28 Rev2 CLN

UR W28 Welding procedure qualification tests of steels for hull construction and marine structures - Rev.2 Mar 2012

UR W29 New

UR W29 Requirements for manufacture of anchors - June 2005

UR W30 Deleted

UR W30 Normal and higher strength corrosion resistant steels for cargo oil tanks - Del 1 July 2015

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