Compliance Assessment Case studies

Case Study: 61508 Proven in Use Assessment

A component manufacturer contacted =Method to determine whether it was possible to obtain SIL certification for an existing product. The valve had been on the market for a long period and was developed prior to introduction of functional safety standards. The manufacturer was not familiar with IEC 61508 and none of their current product range had been assessed against the standard.

=Method analysed the manufacturers returns data for the product, generating the evidence required for a Proven in Use Case. Through calculation of a quantitative reliability figure for the valve, =Method demonstrated that the likelihood of faults that affect the ability of the device to perform its safety related function was sufficiently low enough for the manufacturer to claim a SIL 2 capability for the device. =Method delivered a SIL certificate and assessment report for the valve to the manufacturer, without the need for generation of additional evidence or design changes.

Case Study: 61511 Prior Use Case

Following an inspection from the HSE, a process industry operator required evidence that a device installed in an existing Safety Integrated Function (SIF) was fit for purpose. The operator contacted =Method for support in determining whether the installed device met the requirements for a SIL 1 function.

=Method analysed the evidence available from the operator’s maintenance records to determine whether it was suitable and sufficient for the requirements of 61511 Prior Use. Once this had been established, the data was used to calculate a historical failure rate for the device and estimate the statistical confidence in the calculation. The evidence was compiled into an assessment report and delivered by =Method alongside a SIL certificate for the device.

Case Study: 61508 Proven through Design route – existing device

A component manufacturer had identified that they would have significant market advantage if they were able to claim SIL compliance for an existing product that was relatively new to market. They contacted =Method for support in understanding how difficult it would be to demonstrate compliance.

=Method recommended that the client begin with a “Gap Analysis” workshop, during which =Method delivered an overview of the high-level requirements of IEC 61508 and facilitated a retrospective assessment of the product against these requirements. The output of this workshop was identification of short-falls in evidence of compliance against the 61508 standard and a set of mitigating measures and recommendations to address any non-compliances. The delivered output gave the client sufficient confidence that SIL compliance could be achieved with a minimal volume of re-work to the product. =Method worked with the client to ensure that sufficient evidence existed that applicable requirements of the standard had been addressed and issued a SIL Certificate and accompanying assessment report for the device.

Case Study: 61508 Proven through Design - New Product Development

=Method was contacted by a product developer requiring support to understand how to develop a new device, such that the finished product could be marketed as ‘SIL Compliant’. =Method worked closely with the client to develop a programme of support activities that would maximise the likelihood of a successful product development with minimal impact to the product development cost.

The initial stage of the programme was to deliver a one-day training course to key people involved in the product development process. This ensured that all persons with responsibility for functional safety had an awareness of the full scope of the standard and the reasons it was being implemented for their product. =Method supported the company in development of a set of 61508-compliant company procedures which could then be implemented for all future projects. These procedures were used during development of the new product which was assessed as, and released to market as, a SIL 2 capable device.