Publicly Available Specification – ISO/PAS 23263:2019(E)

In view of the implementation of maximum 0.50 % mass Sulphur fuels (VLSFOs), the International Organisation for Standardisation (ISO), has produced a Publicly Available Specification in order to provide technical guidance in relation to 0.50% mass S fuels. Produced in consultation with a number of industry organisations including ship owners and operators, fuel suppliers and fuel testing agencies, the document details technical characteristics for consideration when purchasing, testing and utilising 0.50% mass S fuels. VLSFOs will continue to be tested against ISO 8217:2005/2010/2012/2017, however the PAS can be consulted in conjunction with the ISO 8217 standard.

The PAS provides specific guidance on the following characteristics:

• Kinematic viscosity
• Cold flow properties
• Stability
• Ignition characteristics
• Catalyst fines
• Compatibility

To encompass the potential for a broad spectrum of fuels ranging from asphaltenic to paraffinic, additional stability and compatibility tests are highlighted for consideration.

The publication is available to purchase from the ISO online store which can be found using the below link:

If you wish to discuss any aspects of the PAS in more detail, please feel free to contact our technical team on +44 (0)1325 390183 or email