Lessons Learned From Chemical Accidents Reported to MARS

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Lessons Learned From Chemical Accidents Reported
to MARS
Institute for the Protection and Security of the
Citizen
The Use of HarsMeth As A Tool For Accident
Analysis
Jaime Sales, EC-JRC-MAHB
Ispra - 2 February 2007
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Analysis of Chemical Accidents

• Runaway reactions are known to be hazardous
  (Seveso).
• Generally unexpected lack of chemical
  knowledge.
• Possible consequences of process failures
  underestimated Process analysis.
• Hazards of chemical substances.
• Companies not always ready to cope with the
  effects of loss of control of chemical reactions
  Mitigation, response.
• A selection of 132 accidents from MARS involving
  chemical reactivity has been analysed.
• Accidents involving chemical reactions.
• Accidents related to decomposition of unstable
  substances or unexpected mixing of incompatible
  substances.

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Consequences of chemical accidents (I)

• Chemical accidents can happen anywhere in a
  chemical establishment.
• Maintenance and cleaning accidents generate the
  most serious consequences.

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Consequences of chemical accidents (II)

• Chemical accidents can happen anywhere in a
  chemical establishment.
• Maintenance and cleaning accidents generate the
  most serious consequences.

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Main causes leading to chemical accidents (I)
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Main causes leading to chemical accidents (I)
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Lessons learned from Chemical Accidents

• Process analysis Process conditions (and
  possible variations) must be studied in order to
  identify hazards related to a process.
• Stability of substances
• Compatibility of reactants
• Critical parameters for a reaction (dosing,
  agitation, etc.).
• Safety measures and control systems It must be
  assured that any parameter identified as critical
  for the safety of the process will always be kept
  under safe conditions no matter what deviation
  may occur (reliability, design).
• Interlocks for chemical reactors (T-dosing,
  T-cooling, Agitation-Dosing, etc.)
• Pressure relief systems
• Organisational measures The development of a
  safety management system is indispensable in
  order to spread an appropriate safety culture in
  a chemical establishment.

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HarsMeth What is it?

• Hazard Assessment of Highly Reactive Systems
  Methodology.
• Developed by EC funded network HarsNet
  (1998-2002). Followed by Safety2Safety (S2S)
  (2002-2006).
• Currently under development by Institut Quimic de
  Sarria, Ramon LLull University, Barcelona
  (Spain).
• Checklist based system to identify thermal
  hazards of batch or semi-batch chemical reactions
  for Small Medium Industrial Companies.
• Available at
• http//www.harsnet.net http//www.s-2-s.org

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HarsMeth Structure
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Failure Scenario Diagram
Decomposition or secondary reactions triggered
Loss of process control
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Stoessel Diagram
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Objectives of Accident Analysis With HarsMeth

• To match accidental causes from MARS reports with
  the issues covered by the methodology to enhance
  accident analysis.
• To identify how the use of HarsMeth could have
  helped to avoid accidents.
• To improve the methodology by identifying common
  failure modes in chemical reactions by means of
  lessons learned.
• To provide recommendations for reporting of
  chemical accidents.

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Safety Management Systems

• Related to routine operations Work permits
• Independent from process

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Preliminary Safety Analysis

• Substances and mixtures
• Usually related to storage and handling operations

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Bench Scale Analysis

• Critical parameters for the reaction
• Analysis of possible deviations from expected
  process conditions

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Industrial Scale Analysis

• General recommendations in relation to previous
  hazard identification
• First action should be to try to eliminate the
  hazard

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Conclusions

• Could accidents in MARS have been avoided with
  the use of HarsMeth?
• Identification of key issues to be reported to
  MARS in case of chemical accidents
• Study has clear benefit for the methodology as
  testing exercise
• Necessity to increase awareness of chemical
  hazards (not only operators, but senior
  management)
• Dissemination of results to companies to improve
  their safety culture

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Lessons Learned From Chemical Accidents Reported
to MARS
Institute for the Protection and Security of the
Citizen
The Use of HarsMeth As A Tool For Accident
Analysis
Jaime Sales, EC-JRC-MAHB
Ispra - 2 February 2007
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Lessons learned from Chemical Accidents Process
Analysis

• Identification of properties of the substances
  involved in the process related to chemical or
  physical stability, including safety margins for
  temperature, humidity, storage time, etc.
• Identification of incompatibility of the mixtures
  that could be generated (intentionally or
  unintentionally) in the chemical establishment.
  Compatibility with auxiliary and construction
  materials must also be studied.
• Identification of those physical and chemical
  parameters (temperature, pH, reaction time,
  etc.), the variation of which could lead to a
  loss of control of a chemical reaction or other
  process operations.
• Identification of possible actions (inhibition,
  extra cooling, containment, etc.) that could be
  taken in order to stop a runaway event.
• Identification of possible physical consequences
  (toxic release, explosion and/or fire) that could
  be originated as a result of a runaway.

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Lessons learned from Chemical Accidents Safety
Measures and Control Systems (I)

• Whenever a hazardous substance has been
  identified, it should be replaced, if possible,
  with a less hazardous one, or at least its use
  should be minimized.
• For storage and transport, the control and
  monitoring of critical parameters of unstable
  substances must be made available. These may
  include, among others, temperature and humidity
  control, and verification of storage periods.
• Measures must be introduced to ensure that
  incompatible substances will not come into
  contact at any stage of the process.
• When using flammable materials, if their use
  cannot be avoided, two conditions are of great
  importance.
• To avoid oxidant atmospheres that may trigger an
  explosion, this can be achieved by the use of
  inert gases like nitrogen.
• To avoid ignition sources such as static
  electricity, hot surfaces, or sparks originating
  from other operations such as welding works.

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Lessons learned from Chemical Accidents Safety
Measures and Control Systems (II)

• For reaction and process operations, sensors to
  monitor the evolution of critical safety
  parameters identified during process analysis
  should be incorporated into the plant equipment.
• Sensors should be interlocked with the equipment
  devices (such as cooling system, dosing devices,
  agitation system, etc.), so that the control
  system can act to restore appropriate process
  conditions.
• The correct functioning of the control system
  must always be guaranteed, for this reason it
  should be a policy to provide redundant control
  systems. These must also be effective and
  reliable when called upon.
• If a loss of process control should happen, it
  must always be possible to stop the activity.
  Systems to kill a reactive process, such as
  inhibitors, addition of solvent to quench a
  reaction, or transfer of reaction mass to
  catchment tanks should be provided.

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Lessons learned from Chemical Accidents Safety
Measures and Control Systems (III)

• The implementation of mitigation measures should
  also be considered in case the risk analysis has
  identified the potential for an accident to
  occur, even if it is considered unlikely. Some
  possibilities would include
• Use of water curtains or foam sprays to dilute
  toxic releases.
• Relief valves or rupture disks or other devices
  to deal with pressure increases in order to avoid
  explosions
• Fire containment and extinguishing systems.
• It must be guaranteed that, in case they should
  be necessary, safety measures are always
  effective and correctly designed.
• It must be granted that supply lines such as
  electrical power, cooling circuits, air, steam or
  nitrogen feeds will always be operational.

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Lessons learned from Chemical Accidents
Organisational Measures

• Preparation of training systems is of primary
  importance. Workers must be aware at any point of
  the hazards involved in chemical processes.
• Detailed maintenance and cleaning procedures must
  be implemented. These have to take into account
  the incompatibility of substances used for these
  operations.
• Emergency plan systems must include the
  activation of defence systems, evacuation routes,
  identification of personnel on site during an
  accident, correct alarm systems, etc.
• Appropriate operating procedures must be
  provided, according to the process analysis.
  After evaluating the hazards of a chemical
  process, the appropriate methods to perform
  common operations should be decided. Some
  examples are
• Implement correct labelling rules and procedures,
  including verification, to avoid mishandling of
  chemicals.
• Provide description of requirements for safe
  handling of chemicals for transport and loading
  operations. This should include personal
  protection measures and equipment (isolation,
  connections, etc).
• Ensure fluent communication throughout a process.
• Ensure appropriate supervision of hazardous
  activities.

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