A report on Accident Scenarios in process plants and how HAZOP can take lead role in prevention

1. A Report on Accident Scenarios in
process plants & How HAZOP can take
lead Role in Prevention
By
Kancherla. Ravi Chandra
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2. Presentation structure
1. Introduction to chemical Accidents
2. Management of Chemical Accidents
 Regulations
 Codes of Practices, Procedures and Standards
 Statutory Inspection, Safety Audit and Testing of Emergency Plans
 Technical Information
3. Case Studies about some of the major chemical accidents
4. Lessons learned from accidents
5. How Process Hazard Analysis (PHA) helps in prevent accidents
6. Role of Hazard and Operability Study – HAZOP
7. Conclusions
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3. 1. Introduction to chemical Accidents
 The growth of chemical industries has led to an increase in the risk of
occurrence of incidents associated with hazardous chemicals (HAZCHEM). A
chemical industry that incorporates the best principles of safety can largely
prevent such incidents.
 Common causes for chemical accidents are deficiencies in safety management
systems and human errors, or they may occur as a consequence of natural
calamities or sabotage activities.
 Chemical accidents result in fire, explosion and/or toxic release. The nature of
chemical agents and their concentration during exposure ultimately decides the
toxicity and damaging effects on living organisms in the form of symptoms and
signs like irreversible pain, suffering, and death.
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4. 1. Introduction to chemical Accidents
 Causative factors for chemical accidents:
Fire.
Explosion.
Toxic release.
Poisoning.
Combinations of the above.
Technical errors
Human errors
Lack of information
Organizational errors
 Initiators of Chemical Accidents:
Process and Safety System Failures
Natural Calamities
Terrorist Attacks/Sabotage
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5. 1. Introduction to chemical Accidents
Impact of Chemical Accidents/ Disasters
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6. 2. Management of Chemical Accidents
 Regulations
Lack of legislation on risk assessment requirements
and classification, labeling and packaging for industrial
chemicals.
Need to identify technical competent authorities and
standardization of reporting mechanisms for the status
of implementation of various chemical disaster-related
activities.
Non-availability of statutes for grant of compensation
to chemical accident victims.
Harmonization and incorporation of international
laws in chemical management.
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7. 2. Management of Chemical Accidents
 Statutory Inspection, Safety Audit and Testing of Emergency
Plans
Safety Audit
Medical Emergency Plans
Inspection System in Factory Inspectorates
Commissioning and Decommissioning Plans
On-Site Emergency Plan
Off-Site Emergency Plans
 Codes of Practices, Procedures and Standards
The specific gaps in these Codes of Practices, Procedures and Standards are as follows:
 Lack of national-level risk assessment criteria and acceptable risks for chemical plants
viz., failure rate and probability of accidents, etc.
 Procedure for conduct of safety audit and safety report preparation.
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8. 2. Management of Chemical Accidents
 Technical
Information, Education &
Training
 Information on Chemicals
 Technical Information & Technology
 Education
 Training of Emergency Services and
District Authorities
 Medical Preparedness and Response
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9. 2. Management of Chemical Accidents
 Technical
Information, Education &
Training
 Capacity Development

Infrastructural

Skilled Manpower

Material Logistics
 Awareness Generation
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10. 3. Case Studies about some of the major chemical
accidents
Case study 1: Bhopal Tragedy:
1984 – Bhopal, India – Toxic Material
Released
2,500 immediate fatalities; 20,000+
total died.
Many other offsite injuries
 Cause:
Most of the safety systems
were not functioning. Many valves and lines
were in poor condition
HAZARD:
Highly Toxic
Methyl Isocyanate
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11. 3. Case Studies about some of the major chemical
accidents
Case study 2: Hindustan Petroleum
Corporation (HPCL) at Visakhapatnam
On 14th September 1997 disaster in
Visakhapatnam refinery is one of the major
failure in industries of India
 Cause:
"A drop in pressure on shore compared with
that on the ship implies a leak”.
"LPG was leaking from the time the ship
started pumping it on shore late last night. It
leaked for several hours as it was not detected.
"The leak could not be detected as imported
LPG is odorless. "The gas is heavier than air, so
it spread at ground level. There was a flash fire
when the LPG ignited”.
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12. 4. Lessons learned from Accidents
 Different lessons learned can be derived by analyzing the causes that lead to the
accidents studied. These lessons learned can be grouped under three
categories: Process Analysis, Safety Measures & Organizational Measures.
I suppose that I
should have done that
HAZOP Study!
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13. 4. Lessons learned from Accidents
 Process Analysis:
Identification of incompatibility of the
mixtures that could be generated in the chemical
establishment.
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 protective measures
(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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14. 4. Lessons learned from Accidents
 Safety measures and control systems:
One should follow proper safety measures and controls while Handling, storage
& Transportation of Hazardous substances & Flammable Materials
First, to avoid oxidant atmospheres that may trigger an explosion, this can be
achieved by the use of inert gases like nitrogen.
Second, to avoid ignition sources such as static electricity, hot surfaces, or
sparks originating from other operations such as welding works.
And now 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.
These sensors should be interlocked with the equipment devices (such as
cooling system, reactant dosing devices, agitation system, etc.), so that the control
system can act to restore appropriate process conditions.
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15. 4. Lessons learned from Accidents
 Organizational measures
Proper training should be given to the all employees &
workers in the plant & Training procedures should
include case studies, describing possible effects of
chemical accidents.
Detailed maintenance and cleaning procedures must
be implemented.
Emergency plan systems must include the activation of
defense systems, evacuation routes, identification of
personnel on site during an accident, correct alarm
systems, etc.
Implement
correct
labeling
rules
and
procedures, including verification, to avoid mishandling
of chemicals.
Ensure fluent communication throughout a process &
ensure appropriate supervision of hazardous activities.
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16. Key Questions to be Answered….!
 Do toxic, explosive or flammable substances in the
facility constitute a major hazard?
 Do chemicals or agents exist
combined, could become a toxic hazard?
which,
if
 Which failures or errors can cause abnormal
conditions leading to a major accident?
 If a major accident occurs, what are the
consequences of a fire, an explosion or a toxic release for
the employees, people living outside the facility, the
plant or the environment?
 What can management do to prevent these
accidents from happening?
 What can be done to mitigate the consequences of
an accident?
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17. 5. How Process Hazard Analysis (PHA) helps in
prevent accidents
Process Hazard Analysis is a systematic effort designed to identify and analyze
hazards associated with the processing or handling of highly hazardous materials;
and it is a method to provide information which will help workers and employers in
making decisions that will improve safety.
 Key Features of PHA
Determine locations of potential
safety problems.
Identify corrective measures to
improve safety.
Preplan emergency actions to be
taken if safety controls fail.
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18. 5. How Process Hazard Analysis (PHA) helps in
prevent accidents
 Common PHA Methods
Hazard and Operability Study (HAZOP)
Checklists
What If
Failure Mode and Effect Analysis (FMEA)
Fault-Tree Analysis
 The HAZARD and OPERABILITY Study is the most commonly used PHA
method in process industries. While the HAZOP method provides more thorough
and complete treatment than other classical PHA methods.
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19. 6. Role of Hazard and Operability Study – HAZOP
 Over the past few decades Hazard and Operability Study (HAZOP) has been
imposing itself as one of the most powerful tools for identifying process hazards.
 In addition, with the use of more or less simplified semi-quantification
systems, HAZOP is being increasingly used both as a tool for risk assessment and for
prioritizing actions for risk mitigation.
 The advantages offered by HAZOP over other process risk analysis tools are
numerous, not least the following:
It has a rigorous character: structured, systematic and comprehensive.
It helps to anticipate potential accidents and it is easy to learn and apply.
It is adaptable to the majority of process industry operations.
It allows the interchange of the knowledge and experience of the participants.
It acts as sort of a training for participating personnel; the participants are
looking at the process from another perspective; not “how should it run”, but
“how can it fail to run correctly”.
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20. HAZOP Study can be applicable to…
Process development
Process definition
Process Design
Procurement &
construction
Commissioning
Operation
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21. A typical HAZOP WORK SHEET
Design Conditions/parameters
Flow rate:
Temperature:
Pressure:
Level:
Node:
Deviation:
Type:
Causes
Consequences
Risk Matrix
S
S - Hazard Severity
L
Safeguards Recommendations
RR
L – Likelihood of hazard occurrence
RR – Risk Rank
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22. Risk Matrix
HAZARD SEVERITY(S)
No
Injury
Likelihood
of
Hazard
Occurrence (L)
Minor Injury Injury or
Moderate
Health
Impact
Death or
severe
health
Impact
Unlikely
A
A
C
C
Possible
A
C
C
N
Likely
C
C
N
U
Very Liely
C
N
U
U
A- Acceptable (No Risk control measures are needed)
C- Acceptable with control( Risk control measure are in place)
N-Not desirable (Risk control measure are to be introduced within a specified time
period)
U - Unacceptable
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23. 7 Conclusions
 The study of past accidents is an effective method to learn lessons to avoid
recurrence of similar situations in the future. For the analysis of specific cases involving
chemical reactivity, the possible failures during a process included in the HAZOP
methodology gives a good possibility to identify the causes of the accidents.
 The lessons learned should be included in the operating procedures of chemical
companies whenever necessary. These lessons involve both organizational and technical
issues; from the management point of view, a true commitment of all staff is required in
order to develop an appropriate safety culture in the establishment.
 Considering the complexity of today's chemical processes, the challenges involved in
facilitating a PHA study, and the potential liabilities from an incident, your best option
for completing PHAs may be to seek the assistance of expert specialists.
 An important benefit of HAZOP studies is that the resulting knowledge, obtained by
identifying potential hazards and operability problems in a structured and systematic
manner, is of great assistance in determining appropriate remedial measures.
 Thus the HAZOP methodology represents an extremely powerful tool for the
identification, semi-quantification and mitigation of risks/ accidents in process plants.
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