The impact of Industry 4.0 on safety instrumented systems

Greater connectivity raises cyber security and other important issues.

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By Rafal Selega, ABB

Industry 4.0 aims to facilitate the interaction between humans and technology by providing information at all industrial plant levels. Persons or tools can access process sensors or final element information (such as measured value or configuration settings, etc.) from any part of the world if authorized to do so. Among other things, this allows device and system performance optimization though delivery of remote services for maintenance and upgrades or repair from a remote location via the “cloud.” Another part of this concept assumes that “smart devices” will communicate with neighboring devices to optimize their own performance based on information about surrounding conditions, e.g., a flow transmitter autonomously compensates its measured value with data from connected pressure or temperature sensors.

The benefit is faster and cheaper optimization than is possible with the current conventional approach because the location of the expert knowledge team doesn’t matter anymore; travel costs and time no longer come into play. Industry 4.0 goes even further. For example, a process operator wishing to optimize the settings for a proportional-integral-derivative controller may use a web-based tuning tool to analyze the current process conditions and dynamics and to provide the optimal tuning algorithm for the valve positioner configuration settings.

Supporters of Industry 4.0 expect inherent optimization features to increase the income of a medium-size process plant by several million dollars per year. In addition, Industry 4.0 should boost production flexibility, enabling a facility to rapidly adapt its operations to market changes. For instance, a plant control system could autonomously adjust output based on fluctuating utility prices, thereby optimizing the costs of production.


However, as with any major shift, Industry 4.0 poses some issues. Many process plants handle flammable, explosive or toxic materials. So, they rely on safety instrumented systems (SISs) to prevent incidents that potentially could result in multiple fatalities or environmental disasters. Industry 4.0 impacts SISs in a number of ways.

Cyber security. The underlying principle of Industry 4.0 is that all systems, including those devices utilizing Internet-protocol addresses, are connected to the globally accessible Internet infrastructure. It is frightening to imagine what could happen if a cybercriminal broke into an Industry 4.0 plant system environment to access and control each and every device associated with the local area network.

Wireless communication. Industry 4.0 promotes the wireless communication layer. By its very nature, wireless communication is open to outside influences from Mother Nature such as lightning, adverse weather, solar magnetic storms and solar plasma ejection. Buildings and plant equipment also can pose obstacles; mobile equipment, new construction, overgrown vegetation, vehicles or temporary screens used for maintenance or repair work can interfere with a signal path. Increased wireless infrastructure also raises the risk of intrusion by hackers and terrorists.

Current functional safety standards don’t allow a risk reduction credit greater than 10 for wireless safety instrumented functions (SIFs). This means wireless devices presently can only be used in non-safety-integrity-level applications. (Refer to ISA TR 84.00.08 for further guidance.)

Real-time constraints. Industrial control systems require real-time reaction, making changes to the systems very difficult. Downloading the necessary data for plant system operation from the cloud requires the plant’s system to access “big data” in cyberspace in real time. Loading available software patches onto the system’s malware scanners and antivirus programs could influence the stability of the process. Any real-time communication must be fast enough to facilitate process automation requirements. For example, a SIF for turbine over-speed protection may need to respond within 10 ms on demand. Currently, the available safety fieldbuses that would form the core of Industry 4.0 are too slow for every process safety application.

Shorter device lifetimes. Some safety devices on the market lack a processor with fast enough response to process conditions or sufficient memory capacity for Industry 4.0; in a short time, they will require replacing. Industry 4.0 may actually lessen device serviceable lifetime, directly impacting capital deployed and increasing operating expenditure.

More-numerous software versions and shortened device lifetime will prevent the user from getting good “prior use” or “proven in use” evidence for a device to be employed in a safety application.

Systematic failure. Devices and systems will boast increased software complexity, due in large measure to powerful new software tools. This means most expected system failures will reside in the software lifecycle. We already depend heavily on software; our dependency will become much greater. Unfortunately, the reliability of current information technology software is far from perfect—Industry 4.0 will ratchet up the challenges.

As our software dependency increases, our incentive for higher levels of software reliability becomes greater. Ultimately, human factors may be the weakest link of Industry 4.0 for safety related systems.

Modularization. Industry 4.0 promotes system modularization. Plants will consist of intelligent modules that may be connected like bricks within the automation foundation. The modularization concept may conflict with the required performance-based approach for the design and development of a safety system. Standards for functional safety and cyber security represent a performance-based approach because experts in this field believe that the plant-specific risk must be first assessed and then the required risk-reduction measures applied to meet defined tolerable levels.

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