Feature Machine Safety The secret life of a plant


Plant managers rely on real time information provided by their plant monitoring software. However, what if these real time reports do not paint an accurate picture? Wayne Matthews of Yokogawa Marex sheds some light on the secret life of manufacturing plants


The HAZOP technique was initially developed to analyse chemical process systems, but has later been extended to other types of systems and also to other complex operations. It uses software to record the deviation and consequence within plant operations. LOPA is a semi-quantitative risk analy- sis technique. It evaluates risks by orders of magnitude of selected accident scenar- ios and builds on information developed in qualitative hazard evaluation.


T


here are two types of risk a plant manager will face during their career - unacceptable risk and acceptable risk. Unacceptable risk refers to accidents that result in long down-time periods and bring harm of any kind to operators and facilities. Accidents and plant down-time occur when people or equipment fail. Most often it is the interpretation the human element gives to the data received from the safety monitoring systems which lead to plant down-time.


As a plant manager you learn from day one that zero risk is unattainable. Instead, a healthy risk-based approach can save time and reduce the scale of existing vulnerabilities, making contin- gency a little more manageable. A risk-based approach to plant man- agement would typically include five steps. The first is the performance of an initial risk assessment to determine system impact. Next, plant owners need to identify the functions impacting staff safety, product quality and data integrity. Following this, one has to perform func- tional risk assessments and identify con- trols. The penultimate stage is to implement and verify those controls. The final step is to review risks and monitor, which can be achieved by implementing a function monitoring solution. Also, plant safety teams are tasked with conducting hazard and operability studies (HAZOP) and creating layer of protection analysis (LOPA) safety plans.


A hazard and operability study is a


structured and systematic examination of a planned or existing process or oper- ation which identifies and evaluates the problems that might represent risks to personnel or equipment, or prevent effi- cient operation.


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equipment that depends on the equip- ment operating correctly in response to inputs, including the safe management of likely operator errors, hardware fail- ures and environmental changes. Safety functions prevent explosions and environmental damage. For instance, in the case of an oil refinery located in the proximity of a housing estate, understanding the environment and potential hazards is literally a matter of life and death.


The virtuous circle


In case of emergency - such as plant shutdown - time is of the essence. For instance, safety monitoring using histo- rian software can save time, because data can be quickly interrogated to find where the fault lies. This also translates to higher plant availability and lower levels of operator error.


Above: safety


function monitoring is the best way plant managers can make sure they keep their operations


secret-free and reduce acceptable risk to


a minimum


Data-based decision making The objective of implementing func- tional safety systems is alleviating the unacceptable risk of physical injury or of damage to the health of people, either directly or indirectly through damage to property or to the environment. It is also a key requirement of complying with HAZOP and LOPA conditions. Most sophisticated facilities collect immense amounts of safety data using a variety of systems. Collating that data and extracting the essential information needed for the safe running of the plant can be challenging at the best of times. However, not having access to ratio- nally compiled safety KPIs (Key Performance Indicators) and reports makes it more difficult to understand the current performance of a facility versus design expectations.


Functional safety monitoring Plant managers need a reliable function monitoring solution that is able to col- lect, process and present safety data. This enables monitoring and analysis of safety KPIs such as SIF (Safety Instrumented Functions) activations, ILPs (Independent Layers of Protection), initiating causes and overrides. Functional safety is the part of the overall safety of a system or piece of


For best practice reasons, plant man- agers can look at implementing virtuous circle theory. This starts with the mainte- nance and operations element of the business. Here, safety function monitor- ing collects activation data from the safety system as well as other devices critical to safety function performance. Moreover, safety function monitoring also collects process data and partial stroke test data to compare baseline per- formance. This enables accurate report- ing on device failure rates.


Thanks to those reports, process tech- nologists can pinpoint the devices or sys- tems that are not performing as expected. After that, the next link in our virtuous circle is related to the key role safety monitoring plays in validating safety activations with successful performance, which helps optimise test scheduling. This allows supervisors to use func-


tional safety assessment reports to make sure they comply with HSE regulations. The principal benefit of safety moni- toring is that it is configured with each individual


plant’s operational risk


assessment expectations and design, including HAZOP and LOPA, in mind. Risk and contingency, as well as events that are partially hidden to the operator, are all part of the secret life of plants. However, overlooking these pre- cious details can have significant finan- cial and safety costs for manufacturers. Safety function monitoring is the best way plant managers can make sure they keep their operations secret-free and reduce acceptable risk to a minimum.


Yokogawa www.yokogawa.com/uk T: 01928 597 100


Enter 209 JANUARY 2014 Automation


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