Unplanned shutdowns are often viewed as operational setbacks but, in certain cases, can unexpectedly be an opportunity to improve the safety of chemical plant operations. These incidents provide an opportunity to conduct proof testing of safety instrumented functions (SIFs) and confirm safety protocols are met without additional downtime.
SIFs act as critical safeguards that protect against safety and environmental risks and prevent mechanical damage during process upsets. Proof tests for SIFs are typically scheduled during plant outages, like turnarounds. However, shifts in outage schedules can threaten the alignment of these proof test intervals with plant operations, potentially compromising the SIF's effectiveness.
The activation of safety functions often plays a key role in safely shutting down the process. This demonstrated activation is direct proof of the SIF components' reliability. In some instances, this can be considered a proof test and is a benefit of an unplanned shutdown.
By recognizing and crediting this functionality, plant operators can lengthen the time between scheduled SIF proof tests, minimizing maintenance costs and downtime. This approach addresses the risk introduced by possible scheduling delays and supports operational integrity and safety.
Strategic Approach to Proof Test Credits
This method credits the shutdowns as unscheduled proof tests and demonstrates the SIF’s effectiveness more frequently than originally intended, which allows an end user to extend the scheduled proof testing intervals of their SIFs.
Guidelines should be created for this process to facilitate crediting the unplanned shutdown. This may include a detailed comparison of comprehensive tests (e.g., full-stroke tests) against more limited evaluations (e.g., partial-stroke tests) to determine whether the unplanned shutdown should be credited as a full or partial proof test.
It can be easy to overcredit this type of shutdown, particularly when portions of the traditional proof test are not executed (e.g., visual inspections). Through a detailed review of each incident, plant managers can analyze shutdown causes, the components involved and the effectiveness of the shutdown in simulating proof-test conditions. This, along with an understanding of component behavior, can help identify which components have been tested and to what degree. End users should prioritize caution in credit allocation and ensure all aspects of the proof test are considered in the process.
Additionally, compliance with regulatory standards may be required. This involves understanding how unplanned shutdowns impact the plant's ability to meet environmental and safety regulations.
Challenges of Integrating Proof Credits
Integrating proof-test credits into safety protocols can involve challenges, such as accurately calculating the extent of applicable credits and assessing their impact on SIF proof-testing schedules. A primary challenge is quantifying the extent of credit that can be applied when an unplanned incident occurs around the time of a scheduled proof test.
Assigning the appropriate credit requires balancing industry standards with specific operational data. Software and data analytics can support estimating the effects of unplanned shutdowns on maintenance timelines and safety system reliability.
AI’s Role in Future Proof Testing and Plant Operations
Automation and AI will likely have a massive impact on proof testing as software's capability for real-time scenario analysis becomes more common. These emerging technologies will strengthen operational productivity and profitability, transforming chemical plant operations and improving decision-making driven by data analytics. AI is progressing so quickly that we'll likely see technologies emerge in the next five years that aren't even on the back of a napkin yet.
Final Notes
Crediting unplanned shutdowns as proof tests can be an effective strategy for maintaining safety while improving operational efficiency in chemical plants. Detailed planning, analysis and documentation are crucial for addressing the challenges related to integrating proof test credits. By viewing unplanned shutdowns as opportunities for critical safety system testing, plants can reduce planned downtime without compromising operational safety.
