Process Safety and the Human Factor

Process Safety and the Human Factor

INTRODUCTION The increasing lifetime of industrial processing plants creates a growing challenge for plant owners/operators to continue to run in a safe and efficient manner. Ageing equipment, especially safety system design and changing legislations, may easily create conditions with demanding requirements. Human factors such as ignorance and habitual routine are often identified as the reason for creating unexpected hazards.

FACTS The average age of production plants in the chemical & petrochemical sector across Europe and North America is rising. Most of the production park originates from the 1960 s to mid 1980 s (30 to 55 years old)

Ageing Plants - Lost of containment effec t Across Europe, between 1980 and 2006, an estimated 96 incidents are reported relating to major accidents due to loss of containment. These being directly connected to ageing plants and loose attitudes. This represents 28% of all reported major accident loss of containment events, approximately 50% of all technical integrity related incidents, the loss of 11 lives, 183 injuries and over 170 Million of economic losses. - Source HSE Report RR823

Plant Design Life The traditional design life for service of production equipment/plant is 25 years For electrical/control and instrumentation equipment the typical design life is 15 years maximum

Effects of Ageing The effect of ageing for industrial installations is not related to how old the plant/equipment is. Ageing is an expression of the condition and change over time of equipment & process. Condition: fitness for purpose of equipment and process.

Pressure Safety Systems Pressure Safety Systems: Are required to protect people and investments against excessive positive & negative pressure from the process. Are an integral part of any process facility and provide the last line of defense against pressure and loss of containment.

Purpose of Pressure Safety Systems Pressure Safety System: - Prevention: Pressure control is always the first option in to control and manage the process conditions. - Protection: Must work when all else fails. Causes could be against catastrophic failure of equipment in case of overpressure and/or underpressure. Must be self actuated!

Safety Systems Ageing Concerns Ageing concern with regards to safety can be expressed as failure to operate as originally intended. Failure to operate can be related to the initially selected design of the protective device/system not being compliant with changed process conditions, or system configurations. Also, lower attention levels on maintenance or operating procedures can lead to an increase in hazards.

Ageing of Pressure Safety Systems Deterioration by time-driven effects ( such as corrosion or mechanical wear) typically resulting in unfitness for purpose or premature failure. Unfitness for purpose relates to potentially unsafe (working or maintenance) conditions. Premature failure may result in potentially unsafe conditions.

Ageing of Pressure Safety Systems - Pressure safety devices must be periodically inspected, functionally tested and where required, repaired. - A study has revealed that up to 34% of installed safety devices (relief valves) in existing plants failed to open as planned/intended. - This can be largely attributed to insufficient or incorrect maintenance or improper usage.

Ageing of Pressure Safety Systems Deterioration by changed discharge system configurations leading to the discharge system being unfit for the intended function. Added or changing effluent handling conditions due to plant geometry change can lead to loss of safety system performance. Requirement for Management of Change (MOC) to assess and document the potential impact of changes to the system.

Risk Based Inspection Risk Based Inspection (RBI): the importance of RBI is increasing due to economical aspects extended availability for service/production. RBI of pressure safety systems is addressed in some industry guidelines (API 580 Recommended Practice for Risk-Based Inspection ). RBI provides a tool to determine preventive replacement intervals prior to actual failure mode is reached.

Effects of Changing Legislation Changes in legislation & technology (such as PED or Machine Directive, ) may lead to subsequent need for design or equipment compromises. Potential deterioration of safety level objectives must be avoided.

Case study:removal of a Safety Critical System March 22 nd, 1987: An intense explosion occured at a hydro-cracking unit in a petrochemical refinery in the UK. - The catastrophic vessel failure and resultant fire caused one fatality and significant plant damage. - Cost of the explosion was 100 million (based on HSE publication The costs of accidents at work )

Case study:removal of a Safety Critical System HP Separator at 155 barg. LP Separator design pressure 10.7 barg. LP Separator Relief Valve sized for Fire. Engulfment not gas breakthrough. Gas Breakthrough not a credible scenario due to low level trips. IPS system disconnected to allow new operating practice. LP Separator failed at an estimated 50 barg.

Case Study: What can we learn? The change to the process operation should have been fully assessed. All cases of overpressure and vacuum pressure should be documented. Where cases are designed out e.g. by Instrument Protective Systems, then the basis of doing so should be included in the documentation and its adequacy (number of isolation valves, instrument redundancy, SIL rating etc.,) be supported by calculations or hazard analysis where necessary. Where protection is provided by IPS then the system should be registered and placed on a regular inspection and maintenance routine. All trips should be regularly tested to ensure their correct and continued operation

Ageing Pressure Relief Systems/Devices Conclusions Ensure that Pressure Relief design and relevant changes are well documented. Review & understand changes, take action based upon inspection data. Ensure Safety Critical Items are installed, understood and maintained. Review the effects of modifications on the relief system. Beware of design creep, assure a documented MOC.

The Solution Pressure Safety Systems - Use simple, tamper-free safety devices such as rupture/bursting discs to avoid that age or attitude ( human factors) can result in an increase of hazards. Explosion Protection Systems - Similar self actuated devices such as explosion vents can be used to avoid catastrophic events.

About Fike Founded 1945 Blue Springs, MO U.S.A. 15 locations, 1250 employees. Globally present...locally active. Innovative process safety solutions: - Pressure safety devices (Bursting/rupture discs: emniyet diskleri ) - Explosion Protection systems (Explosion vents : patlama kapi, Explosion - Detection, Isolation & Suppression) - Fire protection systems / Oil & Gas solutions. - Tested, validated,certified & compliant to global standards.

Ageing of Pressure Safety Systems Thank You For Your Attention! hank.paul@fike.com www.fike.com