Setting a new standard for process safety

Working in a safe environment is something many people take for granted. However, for workers in the process industries, the knowledge that the work environment is as safe as possible will always be of paramount importance.

Functional safety is always a prime concern. Functional safety is defined as 'that part of overall safety relating to the equipment under control and the control system which depends on the correct functioning of the electric, electronic and programmable electronic (E/E/PES) safety related systems, other safety related systems and external risk reduction facilities'. With the increasing use of such systems, the problem of knowing whether a safety system will work effectively to prevent a catastrophe is very real. IEC 61508 is an international standard for safety related systems that sets out a generic approach for all safety lifecycle activities for systems comprised of E/E/PES components used to perform safety functions.

This unified approach has been adopted so that a rational and consistent technical policy can be developed for all electrical safety-related systems. A major objective is to facilitate the development of application sector standards.

Compliance to IEC 61508 allows manufacturers, systems integrators and end-users to demonstrate to customers and the HSE that good practice has been followed through the whole lifecycle and that risks are being managed. Purchasers of systems, or system components, are already using the standard to specify their performance requirements in terms of safety functions.

IEC 61508 is based upon risk assessment. The standard requires investigation based on evidence to judge functional safety. It calls for independent assessment and recommends minimum levels of independence all related to the consequences of failure of the system, and to the safety integrity levels of the system.

Until now, however, it has not been possible to obtain accredited certification against IEC 61508. In September this changed when Sira Certification Service became accredited to certify the Functional Safety Capability of organisations against IEC 61508 using the CASS (conformity assessment of safety-related systems) scheme. This is now being developed to certify other phases of the safety lifecycle.

Developed by industry and supported by the DTI and HSE, CASS provides a framework for a conformity assessment scheme based on IEC 61508. Third-party accredited certification bodies can use it to certify conformity assessment for all activities within a safety lifecycle.

The scope of the CASS scheme will cover all those involved in the specification, design, development, manufacture, implementation, support and application of hardware and software components and complete systems, across many sectors. It will cover off-the-shelf products and application-specific systems, and their operation and maintenance.

The scheme will enhance confidence in the safety of complex E/E/PES systems through an accredited assessment standard. This, in turn, will reduce procurement costs by facilitating reuse; reduce long-term operational and capital costs by facilitating the use of a 'building block' approach; reduce design and development costs; generate increased end-user confidence in current and emerging technologies; promote international trade in certified equipment; and provide a yardstick to national regulatory authorities.

Sira has just received its accreditation from UKAS (the UK accreditation service) based on witnessed assessments carried out over the last few months. Accreditation of the certification process is important as it gives independent assurance of the competence of the certifier and ensures that the results of the process are consistent.

It facilitates recognition of certificates both in the UK and internationally through mutual recognition agreements.

Sira provides a service to certify companies with a Functional Safety Capability Assessment (FCSA). One company that is taking advantage of this is Moore Industries, which provides solutions for companies that need to interface field processes with computer-based systems and instrumentation.

To maintain and improve on high safety standards, process companies should specify that products are supplied by companies whose functional safety capability has been certified to the standard. This will demonstrate commitment to safety, meeting both industry and international standards to accredited procedures.

Using suppliers whose capability has been certified will give engineers and other users the added security of knowing that products have been manufactured for the paramount safety of the industries in which they are utilised.