Chemical processing is an industrial activity involving the use, storage, manufacturing, handling or moving of chemicals. The process can be designed using inherently safer strategies to ensure safe operation under foreseen process upsets. An example of an inherently safer practice is to design a vessel to withstand the maximum and minimum operating conditions existing under emergency operations. When the process is not designed to withstand these conditions, process safety is achieved through the implementation of safeguards that act when conditions become dangerous. Internationally, safeguards are maintained under a program referred to as functional safety management.
The owner/operator has the responsibility to verify that the process is designed, maintained, inspected, tested and operating in a safe manner, regardless of the means used to achieve safety. The safe operation of chemical processes is demonstrated through the data records and information gathered to comply with process safety management programs. The risk of unsafe operation can be lowered by leveraging the inherently safer strategies throughout the entire design, including the safeguard design.
Many types of equipment are implemented as safeguards within the process industry. Long-term sustainability can be significantly different for various safeguards even when designed and managed to provide similar risk reduction. Automated systems, whether in manual or automatic mode, are complex systems where many different devices must work successfully to achieve the desired functionality.
The process control system, safety alarm system and safety instrumented system (SIS) can achieve similar risk reduction, but the resilience of the SIS to human error is higher due to its more rigorous design, verification and validation processes. A pressure relief valve and a check valve are both mechanical devices, yet the pressure relief valve has a more sustainable level of risk reduction in service than a check valve. Making protection layers more resilient to human error is an inherently safer practice. For example, training with real-time simulators can yield faster troubleshooting, higher response effectiveness and safer operation when manual operator actions are required.
Safeguards are designed and managed using a safety lifecycle, which includes myriad activities intended to identify and eliminate human errors. Many different skill sets and planned activities are needed to ensure the safeguards work as desired when required. These activities include competency assessment, verifications, functional safety assessments, configuration management, management of change, audits and metrics. Keeping up with all these activities and maintaining the necessary documentation require a strong safety culture that cares about safeguard reliability. Sustaining attention on the numerous details associated with safeguard performance is a significant challenge.
Automation is undergoing a massive step-change and will take many years to become widely adopted. The latest architectures are information technology networks relying on countermeasures to secure increasingly open communication between plant automation and the outside world. Interconnectivity is highly desirable, but introduces sources of human error and cybersecurity risks that did not exist 20 years ago. “The way things are done” may not be good enough when practices haven’t kept up with changes in technology. Documentation, procedures and training must evolve to keep up.
For more information about how safeguard implementation helps achieve maximum safety during chemical processing, visit www.sistech. com or call (713) 909-2100.
