Health & Safety
Reducing the risk of human error through automation
Start-up, shutdown and transition actions are often the most dangerous periods of operation in the process industries. Ian Curtis argues that companies could consider reducing the potential for human error by employing automated control through safety permissive sequencing at such times of high risk.
Las actividades de inicio, cierre y transición suelen ser los periodos de más riesgo de explotación en los sectores de procesamiento. Ian Curtis argumenta que las empresas pueden pensar en reducir las posibilidades de errores humanos empleando sistemas de control automatizados a través de la secuenciación permisiva de seguridad en estos periodos de alto riesgo.
Anlauf-, Abschalt- und Umschaltvorgänge sind häufig die gefährlichsten Zeiträume in der Prozessindustrie. Ian Curtis führt an, dass Firmen das Potenzial für menschliches Fehlverhalten reduzieren könnten, indem sie eine automatische Kontrolle zur Sicherheit gewährenden Abfolge in Zeiträumen mit hohem Risiko einführen.
gas, petrochemical, chemical and power industries. Here, compliance with the functional safety standards IEC 61508 and IEC 61511 is the accepted and preferred method of demonstrating that overall risk has been managed in accordance with the legal requirements facing all companies. For continuous processes the
T
probability of a hazardous condition occurring is often proportionately greater when the process is in a state of flux such as during start-ups, shutdowns and process transitions.
Safety instrumented systems Te safety instrumented systems associated with these processes are often designed around steady state conditions, but in order to accommodate the non steady state transitions, certain safety instrumented functions need to be bypassed or over-ridden. Tis is where the potential for risk starts to appear. It seems incongruous that, just when it is needed most, the SIS in place is temporarily sidelined and we step away from the intent of the functional safety standards to leave operators to not only deal with the complexities inherent within any process transition, but also perform the SIS function as well. For a continuous process plant such
transitory states are often infrequent and can be of relatively short duration. In such cases it may be that making the safety instrumented system dynamic enough to provide protection at such higher risk occurrences is deemed to be simply not worth the time and expense involved. Te lack of similarity between processes or between the transition state and the steady state may make it too difficult, time-
70
www.engineerlive.com
he use of Safety Instrumented Systems (SIS) is common throughout high hazard process industry sectors, particularly in the oil and
consuming and troublesome to consider and implement an automated SIS solution. In addition, it could be that the operator’s experienced judgment and ability to subjectively assess a complicated situation is seen as essential at such a stage.
“While plant operators commonly perform their role to the highest standards, nonetheless, human error has, after investigation, often been seen to contribute significantly to process safety incidents.”
Ian Curtis, Siemens Industry Automation & Drive Technologies
However, the argument for an alternative view that sees automation technology support the operator during such phases can be seen. It is clear that the operator in question is likely to experience increased stress levels during a plant transition compared to when the
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80