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Lessons Learned From Chemical Accidents Reported to MARS

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Title: Lessons Learned From Chemical Accidents Reported to MARS


1
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
2
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.

3
Consequences of chemical accidents (I)
  • Chemical accidents can happen anywhere in a
    chemical establishment.
  • Maintenance and cleaning accidents generate the
    most serious consequences.

4
Consequences of chemical accidents (II)
  • Chemical accidents can happen anywhere in a
    chemical establishment.
  • Maintenance and cleaning accidents generate the
    most serious consequences.

5
Main causes leading to chemical accidents (I)
6
Main causes leading to chemical accidents (I)
7
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.

8
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

9
HarsMeth Structure
10
Failure Scenario Diagram
Decomposition or secondary reactions triggered
Loss of process control
11
Stoessel Diagram
12
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.

13
Safety Management Systems
  • Related to routine operations Work permits
  • Independent from process

14
Preliminary Safety Analysis
  • Substances and mixtures
  • Usually related to storage and handling operations

15
Bench Scale Analysis
  • Critical parameters for the reaction
  • Analysis of possible deviations from expected
    process conditions

16
Industrial Scale Analysis
  • General recommendations in relation to previous
    hazard identification
  • First action should be to try to eliminate the
    hazard

17
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

18
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
19
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.

20
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.

21
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.

22
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.

23
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.

24
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