Assessment & review of safety-related systems

We offer specialist expertise and experience in the review and safety assessment of electronic instruments (and other software based systems) in accordance with IEC 61508: “Functional safety of electrical/electronic/programmable electronic safety-related systems”. Principal applications include the nuclear, defence and petrochemical sectors.

Safety assessment of software based systems is important since software is capable of introducing systematic failures that are difficult to detect, or cannot be found, by testing alone. The software must be developed against rigorous processes which ensure the safety and correct operation of the system.

It is essential that the assessment of safety-related software includes an examination of the software processes, tools and techniques used during development of the software. Cygnet develops software for business critical and safety-related systems, and is well-placed to independently assess the processes and software of other organisations.

We provide services to assess the functional safety of ‘smart’ instruments (see below) and software-based systems against the IEC 61508 standard and other relevant standards, such as IEC 61513 and IEC 61226 in relation to the nuclear industry. Services include:

• Reliability assessment;
• Liaison with designers/manufacturers/suppliers to collect detailed evidence supporting functional safety claims;
• Assessment of evidence against relevant standards;
• Use of the Emphasis tool for applications in the nuclear industry. This tool provides a rigorous structured objective assessment against IEC 61508 and permits the collation and storage of data (specifications, evidence, auditors’ reports, etc.) in a consistent manner aiding assessment and promoting objectivity;
• Determination of appropriate safety integrity level (SIL);
• FMEA/FMEDA (and software equivalent where appropriate);
• Audit of the supplier’s processes, systems, records and evidence;
• Assessment of software processes to ISO 9001 (TickIT);
• Software code analysis/reverse engineering for safety-related applications;
• Static analysis of software;
• Development of compensatory arguments to address shortfalls in compliance;
• Input to safety cases.

Cygnet with its background in process control industries is able to offer assessment of ‘smart’ instruments. These are now commonplace devices with many manufacturers. Assessing the functional safety of such instruments requires knowledge and understanding of:

• Control and instrumentation (C&I) principles;
• The operation and use of instruments;
• Software development methodologies;
• Verification and validation principles for software.

Many instrument manufacturers claim a Safety Integrity level (SIL) and/or compliance with IEC 61508. Some have been independently certified. The level of rigour employed by each certification body is different, and often the scope of certification excludes the software. An independent assessment by Cygnet provides the assurance that a claimed SIL is well-founded.

For more information on any aspect of our ICT consultancy work, please contact sales@cygnets.co.uk.