High integrity pressure protection systems (HIPPS) are widely used for preventing pressure spikes in pipelines and critical process units. If the mechanical relief layers or conventional controls fail, they’re designed to be incredibly robust last-resort defenses. To maintain functional security integrity, HIPPS shall be kept electrically, logically and cyber-safely separate from control and diagnostic systems. This isolation limits the ability of the operational teams to observe the operation and evolution of the pressure transducers, logic solvers and final components, even though this is required to meet the safety integrity level (SIL). This is why it is a constant challenge to maintain strict independence of functional safety while improving life cycle performance, diagnostics and reliability.
Advantages of edge computing
Recent developments in edge computing provide practical solutions. By introducing a read-only, non-interference layer of edge analytics, operators can obtain real-time insights from the HIPPS without compromising security routes, lockdown logic, or SIL certification. The components of the HIPPS system are affected over time by environmental changes, mechanical wear and stress. The potential experience for operators includes degradation of the response time or the torque of the actuator, slow sensor drift or bias that cannot be detected by the logic solver, limited justification for changing the test interval, difficulties in performing continuous SIL performance evaluations and possible safety blind spots in remote or unmanned installations where the behavior of the device is not sufficiently transparent. Many of the midstream and upstream environments—where pipeline segments, well sites and subsea assets are often not manned—exacerbate these visibility gaps. A layer of non-interference analysis can enhance maintenance planning, lower uncertainty and support lifecycle safety management.
Design considerations
Strict independence requirements must be met by edge analytics architecture to coexist with HIPPS and preserve operational security. For example, the output of field transmitters shall be passively duplicated with isolators or signal-splitting devices. Since the reflected signal is sent to the edge device, the path of the security signal remains unchanged. The HIPPS analytics platform and the HIPPS logic solver shall not share hardware, Internet of Things (IoT) modules, backplanes or memory. Independence is one of the main requirements of IEC 61508-61511. The safety logic cannot be affected by diagnostic information due to the transmission of data only through OPC UA, MQTT or RTU streams. For cyber separation, one-way gates or diodes are recommended.
The analysis node shall not be able to modify security logic or send termination orders. A certified logic solver shall retain full control of all HIPPS operations. While HIPPS strictly follows the safety-of-knowing zones, the analytical components are located in the enterprise or supervision zones. This architecture maintains the independence required for SIL 2, 3 and 4 applications while allowing better monitoring.
The visibility provided by the edge should never compromise the integrity of the SIS. It is recommended that security and analysis networks be strictly separated, that remote program access to the logic solver is forbidden, that one-way data transmission mechanisms are used, that ISA and IEC 62443 zones and circuits are used and that independent authentication and access controls are put in place. The edge device should be used as a supervised diagnostic tool and not as a control element.
Benefits of using a non-interfering edge device with traditional HIPPS:
By examining long-term behavioral trends, the non-interactive edge analytics layer can continuously assess the health and stability of HIPPS pressure transmitters. The sensors may eventually show signs of slow bias accumulation, zero or span instability, environmental drift or irregular response patterns that are not immediately apparent to the logical solver. As these problems often develop gradually, they may go unnoticed until a particular requirement creates the potential for a dangerous failure. Operators can address emerging sensor degradation well before it affects safety functions by using analytics-based monitoring to help early detection of such changes.
Even slight endpoint degradation can have a substantial impact on the probability of a demand failure (PFDavg), which is one of the most crucial elements for the overall reliability of HIPPS. Edge analytics can track changes in the torque requirements of the actuator, track trends in partial stroke test signatures, track variations in valve opening or closing times and identify early indications of seat leakage. The valve assembly’s mechanical condition can be inferred from these operating patterns. Early performance degradation detection enables targeted maintenance interventions to increase system availability and dependability.
The optimization of testing strategies can be greatly facilitated by historical diagnostic data collected through edge analytics. Evidence of stable device performance and high diagnostic coverage may support longer test intervals if warranted by the safety case and reduce the frequency of service breakdowns.
In addition, condition-based maintenance tasks can be planned based on the behavior of the equipment in the real world, rather than on predetermined intervals. to maintain SIL compliance throughout the lifecycle, any change in the test frequency shall always be supported by updated reliability calculations and documented compliance with the requirements of IEC 61511. Predicting algorithms may improve the original design assumptions. Using a Bayesian update, the operator can recalculate the PFDavg, MTTR, diagnostic coverage and the probability of a false-positive trip. These metrics improve the fit between the actual behavior and design stage assumptions.
Applications across critical energy infrastructure
The operation and maintenance of gas transmission compressor stations, offshore wells and pipeline risers, remote or unmanned midstream assets and gathering system overpressure protection may benefit greatly from the application of non-interfering analytics. Real-time visibility can significantly increase safety when traditional manual inspections are impractical.
Final thoughts
Significant operational insight is not hampered by the need for HIPPS to remain isolated to preserve functional safety. A well-designed non-interfering edge analytics layer enables operators to monitor device health, spot emerging reliability problems and support lifecycle performance enhancements without altering the certified safety function. As energy infrastructure becomes more distributed and automated, functional safety and intelligent diagnostics will become increasingly important for risk management and improving system resilience.
