Plant controls and safety initiatives for industrial facilities
Safety for the industrial automation worker is a two-sided coin. It depends on the safety layers built into the process operations as well as the process operators’ dedication and knowledge of safety strategies and policies. Control systems have automated safety layers that are designed to prevent accidents, but machines and alarms can only handle so much of the risk. The remainder of that responsibility-and the key to minimizing risk-lies with people and the safety strategies that are followed.
Layers of risk reduction
A basic process control system (BPCS) is typically designed to have layers of safety functions and built-in safeguards to eliminate or reduce hazards. The BPCS runs the process, but also functions as the first line of defense for the operators through independent protection layers (IPLs). It identifies abnormal situations, such as an out-of-tolerance measurement or other issue, and sets off an alarm or takes another action in response.
To address the next layer of safety risk, a process hazard analysis (PHA)/hazard and operability (HAZOP) study or other audit is performed to determine the remaining safety-related issues or to identify those situations or other potential system failures that could happen to cause an accident or issue. Next, the safety instrumented system (SIS) layer is designed to minimize those risks that have been identified as unacceptable through the HAZOP study. It’s integrated with the BPCS with independently operating safety instrumented functions (SIF). SIS importance is heightened as the BPCS ages, when it lacks maintenance or even when the skill level of operators shifts through employee attrition or lack of knowledge.
Even with all these built-in protection layers and safeguards, it’s still necessary to monitor and maintain safety systems. Having these systems in place doesn’t eliminate the need for on-site personnel. Nothing is 100% failsafe.
A safety risk can arise at anytime, anywhere, due to any combination of factors. Therefore, it’s vital to have safety initiatives, strategies, and policies in place. There should be a zero-tolerance policy for not adhering to safety policies and procedures to ensure the life safety of personnel.
Operator safety awareness
Complacency is the enemy of process operations. This is an area where a corporate culture and policies can have the biggest influence on safety—by working hard to keep safety policies and procedures ingrained in operators and other personnel to keep them well-trained, informed, and vigilant. Operator training and sharing tribal knowledge is key. Ask the following six questions to ensure operators are well-trained:
1. Do the operators understand their role in keeping themselves and others out of harm’s way?
2. Are they trained on situational awareness and do they know where to go for help and what to do in an emergency?
3. How well do they know the facility’s system and the danger it holds?
4. Are they kept up to date on changes to the systems and processes?
5. Do they know best safety practices for tasks they may be asked to perform that are unfamiliar or outside the scope of their normal workload?
6. Is their system designed to interface with operators in a clear, concise manner with the right information available at the right times?
For some systems, operators can get overloaded with information and may unintentionally miss taking the necessary action needed to prevent a safety risk. For example, on some older human-machine interface (HMI) screens in a control room, the colors may be inconsistent. An operator might see an array of alarm colors to indicate potential failures or compromises such as a stuck valve or pressure rising or a tank overfilling. In one part of the facility, the alarms might turn blue and yellow to open and close a valve, but in every other area, the colors turn green and red. An operator might wonder if seeing "red" is abnormal or not, which creates confusion. The control system may sport a sea of colorful icons on its monitor, but fancy graphics may impede the operator in recognizing critical alarms. Alarms often seen may be considered a nuisance and ignored because it’s the "norm" to believe they don’t indicate a serious safety risk.
Safety incidents occur when operators can’t tell the difference between a critical event or a normal one. High-performance HMI graphics help operators to identify alarms using grayscale screens with consistent colors or shapes. However, operators should still be properly trained on critical alarm elements and other piping and instrumentation diagram (P&ID) symbols and be able to recognize and respond to abnormal situations. They also should have a clear understanding as to what’s happening with the facility’s systems and processes.
Trained operators are the key to taking advantage of the BPCS and SIS’s automated safety functions. One is the right hand and one is the left. Without one or the other, the risk of an incident increases. For example, if a BPCS or SIS is giving off a warning signal and it’s ignored, or the operator is not properly trained to identify its warning signs, it defeats the purpose of having system safeguards.
By the same token, if measures are being taken to lower facility risk, but the equipment is degrading or the proper machine or predictive maintenance policies and procedures have not been followed, benefits are easily negated. If a PHA/HAZOP audit outlines potential risk factors in systems, the right course of action is to heed the recommendations to prevent a potentially catastrophic event. It’s important to have a cohesive safety policy in place that includes the personnel and how the facility is run.
Risk tolerance level
As part of the process to further corporate culture safety strategies, policies and initiatives, look at the larger automation picture and perform an analysis of systems and processes that are in place. In doing so, it’s them important to determine the tolerable and intolerable risks. Key areas will be to review whether all of the facility’s automation, safety systems, and personnel work together to ensure safe and secure operations.
Answers and guidance is available in industrial safety standards, including the IEC 61511; Functional Safety-Safety instrumented systems for the process industry sector and ISA84-Standard for Safety Instrumented Systems that can help with SIS and SIF decisions. The process is a huge undertaking and may require help from a platform-independent automation solutions provider, who can combine process and automation knowledge with SIS expertise to help improve operations and analyze safety factors. Operators will also need to be trained to understand their roles in the larger safety picture and tolerated risk levels.
Safety doesn’t just happen. It greatly depends on buy-in from all areas of a facility-management, engineering, operations, maintenance, etc. It requires a mix of process control safeguards and safety policies, strategies, and initiatives. With these elements in place, an effective corporate safety culture can be built to keep automation systems and people safe.
Susan Colwell is publishing and content development manager for Maverick Technologies, a system integrator and CFE Media content partner. Edited by Emily Guenther, associate content manager, Control Engineering, CFE Media, firstname.lastname@example.org.
Susan Colwell, publishing and content development manager for Maverick Technologies, has more than 25 years of experience editing, writing, and publishing technical content for the industrial automation and control industry.