CASS Documents

The templates of the CASS methodology can support consistent compliance of IEC 61508 and related standards.

The assessment of functional safety can be challenging and there are many aspects to consider and assess through the process. The CASS templates are designed to guide / support a competent assessor through various aspects of functional safety (dependent upon the specific form). Further details on CASS can be found on the CASS webpages of this website.

The CASS Scheme Association management team welcome feedback on the content and use of the documents. Feedback can be provided either directly to the CASS Scheme Association or via The 61508 Association (contact us).

Important Note: Anyone is welcome to use the CASS templates, however, it must be realised that when performing conformity assessments, an appropriate level of competence is required of the assessor in the specific area that is being assessed. Please also review the CASS guide and especially the CASS disclaimer.

Conformity Assessment templates

The conformity assessment templates referenced in the above chart can be downloaded from the links below once they are available.

• Guide to using the CASS methodology
• Rules for use of the CASS logo (Applicable to certification bodies)
• CASS disclaimer (An important notice to all those using the CASS methodology)
• Functional Safety Management Declaration Lodged with CASS-appointed Body

• CASS RFSA Scheme Manual.
• Competence requirements for CASS Assessors Product Certification to IEC 61508.

• CASS TOES for the Functional Safety Assessment process from IEC 61508-1_2010 v1.

• Cross reference between IEC 61508-1:1998 and IEC 61511-1:2003 for Management of Functional Safety 

• The list of current registered functional safety assessors can be found here.

• CASS TOES for Functional Safety Management Assessment to IEC 61508-1:2010 (becomes CASS-508-A).
• CASS TOES for the Overall Safety Lifecycle Assessment to IEC 61508-1:2010 (becomes CASS-508-C).
• CASS TOES for the E/E/PE System Safety Lifecycle Assessment to IEC 61508-2: 2010 (becomes CASS-508-D).
• CASS TOES for Element and Sub-systems SIL-capability Assessment to IEC 61508-2:2010 (becomes CASS-508-E).
• Guide to CASS-508-F - CASS TOES for software assessment to IEC 61508-3:2010 (full requirements).
• CASS-508-F - CASS TOES for software assessment to IEC 61508-3:2010 (abridged for audit).

• CASS TOES for FSM Assessment to IEC 61511-1:2016 (becomes CASS-511-A).
• CASS TOES for Functional Safety Assessment (FSA) to IEC 61511-1:2017 (becomes CASS-511-B) - Available soon.
• CASS TOES for the SIS Safety Life Cycle to IEC 61511-1:2016 (becomes CASS-511-C).

• CASS-061: CASS TOES for the SCS safety lifecycle (all aspects) to IEC 62061:2021.

Summary Papers

The following documents summarise important requirement of IEC 61508 and related standards. Each paper targets a specific audience or a specific subject. The papers are intended for those needing a quick overview of Functional Safety as defined in IEC 61508.

• T6A001 - IEC 61508 for Directors responsible for overseeeing projects that involve the 61508 group of standards.
• What is functional Safety Management?  - A brief overview of what Functional Safety Managemenet includes.
• Process Safety and Functional Safety - Can you spot the difference?
• T6A002 - IEC 61508 for Senior Management  overseeing applications that use the IEC 61508 group of standards.
• T6A003 - IEC 61508 for Installers for those companies undertaking installation and commissioning work under the IEC 61508 standards.
• T6A004 - IEC 61508 for Maintenance Engineers undertaking installation and commissioning work under the IEC 61508 standards.
• T6A005 - IEC 61508 for Operators of plant or equipment that involve SIL rated safety functions, trips or interlocks.
• T6A006 - IEC 61508 for Project Engineers  and project managers undertaking a project using the IEC 61508 group of standards.
• T6A007 - IEC 61508 for Purchasers  purchasing goods and services for the IEC 61508 group of standards.
• T6A008 - IEC 61508 for Quality / Inspection Engineers  involved with a project using the IEC 61508 group of standards.
• T6A009 - IEC 61508 for Salespersons  promoting products and services for projects requiring compliance to IEC 61508 standards.

• T6A010 - Combined basic Process Control systems and Safety Instrumented Systems  A document to aid the demonstration of Independence between Control & Safety based upon both IEC 61508 2nd edition and IEC 61511 1st edition
• T6A011 - Where Process Safety meets Machine Safety A brief overview of combining machine and process Functional Safety.
• T6A012 - SIL rated alarms – Can you really afford them? Key points for those considering having a SIL rated alarm under IEC 61508.

Technical papers and guides

The following documents are intended for those needing a more in-depth consideration of technical issues. Where there is a companion in the section above, it is recommended they be studied together.

• T6A033 - FS Certificates and Safety Manuals (2022)
• T6A032 - Considerations for Cybersecurity during the Safety Lifecycle (2020).
• T6A031 - The Requirements of a Design File for a Safety Instrumented System (SIS) in accordance with IEC 61511 (2020).
• T6A030 - Functional Safety Assessments (2019)
• T6A029 - ALARP - As Low As Reasonably Practical (2019)
• T6A028 - Cyber Security - An introduction for Functional Safety Systems (2017).
• T6A024 - Proven in use (2017)
• T6A023 - When Process Safety meets Machine Safety to aid understanding between the end user and machine builder (2016).
• T6A022 - EPC Roles and responsibilities (2016).
• T6A021 - Combined BPCS and SIS Systems A document to aid the demonstration of independence between Control and Safety (2015).
• T6A020 - Cyber Security - Initial concepts (2014).
• T6A019 - SIL Calculations - easy or difficult? A presentation by Sella Controls / Hima-Sella (2012).
• T6A018 - Legacy System Management (2011).
• T6A017 - Basic Priciples for the Functional safety of Legacy systems (2009).
• T6A016 - Maintaining Safety Instrumented Systems (SIS) (2009).

Technical Paper for Public Comment (please use the "contact us" option if you wish to submit comments):

• T6A041 - Reliability and Availability (2022).
• T6A042 - Effects of Proof Testing (2022).
• T6A043 - Fault Tolerant Systems (2022).
• T6A044 - Staggered Proof Testing Coefficients (2022).

Technical papers presented by members

Technical papers presented by members of the 61508 association

Achieving Hardware Fault tolerence: Paper presented by Mirek Generowicz of I&E Ststems Pty - Australia 

Competency based assessment in Functional Safety: Paper presented by Mirek Generowicz of I&E Sysems Pty - Australia

Cyber security - Paper presented by Peter Brown of Siemens Ltd.

Demonstrating Prior Use: Paper presented by Dave Ransom

Practical SIS Design and SIL verification: Paper presented by Paul Reeve of Silmetric

Reassessing Failure Rate Data - Paper presented by Mirek Generowicz of I&E Ststems Pty - Australia 

Systematic capability for Elements: Paper presented by Paul Reeve of Silmetric

The use of an operator as a SIL1 component: Paper presented by Andrew Derbyshire of DNV Ltd

New approach to SIL verification: Paper presented by Mirek Generowicz of I&E Systems Pty - Australia

Miscellaneous

Miscellaneous downloads from 61508 Association.

The 61508 Association Logo

• Guidelines for the use of the logo Guide for the use of the 61508 logo.
• 61508 logo (gif)
• 61508 logo (png)