Procedural Automation to Improve Operation Safety and Efficiency
/Operational procedures are an important component to the safe and efficient operation of process plants, including gas processing and pipeline transportation. These procedures consist of a set of tasks that need to be executed in a consistent manner, time-after-time, in order to achieve a specific objective such as starting up, shutting down or transitioning a process through a feed change or a maintenance activity.
What follows will highlight an emerging standard ISA106, which focuses on Procedural Automation for Continuous Process Operations and covers the following:
Key definitions so that owner/operators, automation vendors, and system integrators can use commonly understood terms to discuss requirements.
Models such as equipment and procedural models where systems can be designed to be modular and flexible, reducing engineering and total lifecycle costs.
Overview of benefits such as reducing operational errors, improving process efficiency and enabling more efficient responses to process upsets.
Introduction
Throughout upstream, midstream and downstream of the energy and petrochemical value chain, most processes can be considered continuous and steady states. But separation plants, well pads, processing units and pipelines still need to be started up, shut down or transitioned from one set of operating conditions to another.
Despite the strong focus on safety in the process industries, there continues to be incidents and many are caused by operational errors. For instance, in an analysis of pipeline failure investigation reports, incorrect operation was listed as the primary cause 15% of the time. Additionally, incorrect operation has been a contributing cause in many of the incidents involving equipment or material failure due to repeated incorrect operation over time causing stress on the system.
In the development of process control systems over the past 30 years, both Programmable Logic Controllers (PLC) and Distributed Control Systems (DCS) initially focused on discrete and continuous control. Procedural control functions were added later and the logic was more complex. Batch processes are procedural in nature, but typically involve sets of procedures running in parallel on varying process units and almost always need to have inbuilt flexibility. The ISA88 standard released in 1995 addressed batch automation very well and was widely adapted in food, pharmaceutical and specialty chemical industries. But the execution of procedures in continuous process applications remained a very manual and intensive task for board and field operators, who can be prone to human error and cause safety incidents or inefficient process operations.
The Benefits of Procedural Automation
Reduced Variability: When procedures are performed manually, there is often a large variability in how they are executed by different operators. Automating procedures enforces consistent execution of procedures and operation of the process, resulting in reduced process variation and higher throughput. Operators are able to operate with fewer errors and less stress, enabling them to concentrate on the overview of all the processes they are responsible for in the control room or a higher situational awareness. This results in more efficient and safer operations.
Capturing Operator Knowledge: In many plants, the existing paper-based Standard Operating Procedure (SOP) manuals contain the “static” knowledge documented when the production platform was being built and brought on-line. Over time, the actual procedural knowledge and skill resides more and more in the heads of the most experienced operators. In many cases, this knowledge and the accompanying skill sets are leaving the workplace due to retirement, and the availability of experienced operators to run these procedures manually is diminishing. How to preserve the knowledge of the best operators is an important need in many process plants and pipelines. Additionally, many plants and pipelines continue to operate with lean technical staffs and the level of technological complexity is increasing. The timely flow of information, data, and knowledge is more important than ever in the process industries. This increased demand for accurate, real-time information will translate into additional systems and higher, more sophisticated levels of automation. The smaller, less experienced workforce that will exist in the future must be empowered with new technologies and workflows that can transfer knowledge on demand.
Figure 1 below depicts the methodology of capturing procedural best practices. The goal of this approach is to “distill” best operating practices of operators and find the right balance between manual and automated procedures, documenting and implementing the procedures and then performing continuous improvement cycles on them. Automating every procedure does not always provide the best solution. What does provide the best solution is to consciously examine events, then examine the procedural operations associated with those events, document them and determine what type of implementation will provide the best operational result while improving safety, health and the environmental metrics for the facility.
Figure 1: Capturing Procedural Best Practices
Improving Process Flexibility and Reliability: By automating procedures, the goal is to improve overall performance through faster and smoother transitions from one set of process conditions to another. This contributes to extended equipment life and optimized production, throughput or product yield. There are three broad operational procedures involving transitions: start-up, shut-down and unit state change. The unit state change includes transitions like grade changes, production rate changes, process equipment switches, etc. Managing state transitions through procedural automation can be applied to a complete process unit and to a selected piece of equipment in a process unit, like a shut-down valve, or a test separator or a heat exchanger.
Additionally, procedural automation can address issues like a process trip resulting in a unit shut down or a larger event causing a plant-wide shut down. In some abnormal conditions, most of the time there is an opportunity for a process operator to reset equipment and operating conditions, to re-establish normal conditions before a safety system shut-down. The goal is to minimize production rate disruption. But the time window is narrow, very challenging, and stressful to execute during an abnormal event – and most often the affected process is brought to a much longer shut-down state with the result of higher production losses.
Challenges in Automation Procedure
For the last 20 years, many owner/operators in the process industries have made an attempt at automating procedures. Often, a dedicated engineer would go in and write code in a control system or a bespoke sequential control software application and meet with initial success in implementing automated procedures. Commonly, the engineer would transition to a different job and a new engineer would take responsibility. However, the procedural code would not be structured or documented well which would make the new engineer reluctant to make updates, changes and improvements. This typically would cause the automated procedures to fall into disuse and the plant operators eventually return the traditional ways of using manual procedures. Batch manufacturers had a similar problem and developed an industry wide standard, ISA88 in 1995 where end-users, automation vendors, and system integrators were able to apply the same common definitions and structural models to solve procedural control and automation. Many attempts were made to adapt the ISA88 standard to continuous process application but it was never widely adapted because it did not address many requirements in continuous process applications.
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ISA106: An Emerging Standard to Address Automation Procedures in Continuous Process Applications
In 2010, the ISA (International Society of Automation) approved the formation of a new committee and it adopted the title “Procedural Automation for Continuous Process Operations.” At the first meeting in June 2010, the committee agreed that its purpose was to develop standards, recommend best practices and publish technical reports on the life cycle of automated procedures for continuous process industries.
Over the last 5 years, the committee has grown in size substantially. It has received input and support from 39 manufacturers and suppliers including many energy companies that run refining, petrochemical, midstream and upstream operations. The committee met their goal to publish a technical report based on good practices that are used today. The technical report was approved in August 2013 and published by the ISA. Currently, the committee is working on refining the material to publish a standard.
Some of the contents that would be relevant to the standard are as follows:
Common Definitions and Terminology:The technical report has defined a common set of 52 terms with uniform definitions to describe the requirements for improvements and changes in automating procedures. This improves communication between EPCs, system integrators, automation suppliers, and internal company functional departments. The primary models that are used in the technical report to organize equipment and procedures are as follows:
Physical Model: Organizes physical equipment into a hierarchy that is the foundation for the Foundation of the ISA106 work. Each item in the model can have procedures associated with it. The model’s common set of terms and equipment levels allow for companies in different industries to map their terms to such. A mill in the paper industry would be associated with the common term plant.
ISA 106 Key Models
Procedural Requirements Model: Procedure requirements are the definition of what actions are required to accomplish an objective. They are used as functional requirements when automated procedures are implemented. Procedure requirements may exist at any physical model level.
Procedure Implementation Model: This model shows the hierarchy of implementation modules that result from implementing procedure requirements. Implementation modules are created based upon procedure requirements. They represent the configured or programmed result of implementing procedure requirements in the control system used for the process.
Summary
The value of procedural automation is well-proven in many different process applications. Properly designed and programmed, it will improve repeat-ability, utilization, and safety of your process. Still today, many procedural operations in continuous applications are run manually and often inefficiently and sometimes unsafe.
With pressures to reduce costs, improve quality while reducing safety and environmental incidents, and an aging workforce - automating procedures offers the ability to preserve and manage a plant and a company’s overall operational/procedural knowledge and improve safety performance.
Modularizing the design and implementation also provides cost savings, while allowing the flexibility to make changes without impacting production. The ISA106 Technical Report and upcoming standards committee can provide guidance in implementing procedural automation.
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