Automation World: What is the biggest challenge you’ve seen in implementing a successful safety integrated system (SIS)? Angela Summers: The biggest challenge is maintaining the good engineering practice of a separate and independent SIS in a world where everyone seems to be seeking complete integration. A defense-in-depth strategy remains the hallmark of good engineering practice that has repeatedly yielded proven system integrity, reliability and security. If any single component failure, whether due to human, software, firmware, hardware, utility or communication faults, can disable multiple systems, the implemented solution has violated the long-standing practice of independence and separation. Too often, users assume that [the International Electrotechnical Commission standard] IEC 61511 requires that the SIS be implemented using a programmable electronic system. That is simply not the case. In many cases, conformance to the standard can be achieved using a stand-alone hardwired system.AW: How have engineers and managers juggled conflicting demands of production, quality and safety?Summers: While the reliance on instrumented systems has increased at an incredible pace, the resources allocated to properly assess, design, operate, inspect, test and maintain these systems has declined, leading to significant deficiencies in instrumented system performance. It is unfortunately all too easy to find evidence of poor performing instrumentation and controls, inadequate operating and maintenance procedures, poor recordkeeping and retention practices, and out-of-date documentation. The user is ultimately responsible for safe operation and for determining that equipment is fit for service. The top-performing companies are continuously working to improve the quality of their mechanical integrity and reliability programs to ensure their safety systems operate as specified when required. Those who continue to cut corners find it increasingly difficult to ensure safe operation. Some facilities are operating near the edge of a catastrophe.AW: If readers learn nothing else from your book, what is the one thing that should be implemented?Summers: Management must be fully committed to and engaged in the development and implementation of a rigorous management system for instrumentation and controls installed in protective applications. Commitment requires establishing safe and reliable operation as a priority and providing the resources, tools and training needed to get the job done right. The management system should address how each instrumented protective system is designed and managed to achieve seven core attributes: independence, functionality, integrity, reliability, access security, management of change and auditability. To be sustainable, these attributes should be considered in each project and operational phase so that improving process safety and reliability are a normal part of doing business.
