What can be done to Prevent Accidental Toxic Release, Fire & Explosion in Chemical Process Industry?-Juniper Publishers
Juniper Publishers
Abstract
Public perceptions are significantly affected by
industrial incidents and the contribution and essential societal role of
different industries are often overlooked when any catastrophic
incident occurs. What can be done to prevent release of toxic chemical,
fire & explosion or any other catastrophic incidents? Majority of
the incidents occurred in the process industries due to lack of
competence, system failure, human error and/or someone did not do what
they were supposed to do. The root causes of the incidents in process
industries are more or less same. The incidents can be avoided if the
organization maintains a positive safety culture to improve its process
safety performance and take advantage of lesson learned from the
previous incidents. Everyone in any organization starting from the
Chairman and Chief Executive Officer, senior executives, supervisors and
operators should be accountable and responsible for their appropriate
roles to ensure health and safety performance of the company.
Keywords: Bangladesh; Chemical Incidents; PSM Standard; Lesson Learned; Toxic release and Fire & ExplosionIntroduction
The toxic and hazardous chemicals release, fire
& explosion were pretty frequent which caused multiple fatalities,
injuries, significant property and environmental damage [1-3]. The
question remains that can the occurrence of these disastrous accidents
be reduced in the future and their consequences minimized? An effective
implementation of Process Safety Management (PSM) program in the process
industries could significantly reduce the risk and avoid catastrophic
fires, explosions, releases of hazardous substances and/or minimized its
consequences. In United States, process industries are required to meet
OSHA PSM standard. OSHA Process Safety Management (PSM) standard has
fourteen majors’ interrelated elements [4]. Employee Participation,
Process Safety Information, Process Hazard Analysis (PHA), Safe
Operating Procedures, Training, Contractors, Pre-startup Safety Review,
Mechanical Integrity, Hot Work Permit, Management of Change, Incident
Investigation, Emergency Planning and Response, Compliance Audits and
Trade Secrets. All of these elements are equally important. Among them,
process hazard analysis (PHA) is heart of OSHA’s Process Safety
Management (PSM) standard. Process hazard analysis is a thorough,
orderly and systematic approach or technique to identify, assess and
control the potential hazard associated in process industries. Process
hazard analysis must need be
conducted to identify all causes, estimate the risk and develop
strategies to address the risk in chemical process industries.
Many of the developing countries (e.g. Bangladesh)
do not have the process safety regulations/standards for process
industries. There are significant numbers of industries in Bangladesh
dealing with toxic, flammable and others hazardous chemical or materials
those have potential to cause serious harm to employees, public and the
environment. The number of chemical incidents is also increasing in
Bangladesh these days. There were three major chemical incidents in 2016
which caused 40 fatalities, significant property and environmental
damage. Quite often the accidental release of toxic chemicals, fire and
explosion are narrowly defined and include only the ones that caused
serious or catastrophic consequences [2].
The government or regulatory authorities should
adopt the process safety management standard for process industries if
they don’t have yet. An effective implementation of process safety
management program in the process industries and monitoring the process
safety performance are required to avoid any future catastrophe. The
process industries should have a good incident investigation procedures
necessary to take advantage of the lessons learned.
Major Safety Incidents
Piper Alpha, a North Sea Oil Production Platform was located
approximately 120 miles Northeast of Aberdeen. On 6th July
1988, an explosion occurred on a North Sea oil production
platform known as Piper Alpha which killed 167 employees.
Total property damage from the explosion was estimated to be
approximately $1.4 bn. A safety relief valve for a spare condensate
pump was removed and temporarily sealed with a blind flange by
the day shift operators. Unaware of the temporary replacement
the night shift operators restarted the spare pump and gas
condensate leaked from the flanges and ignited. The incident
was attributed mainly to human error and an eye opener for
the offshore industries regarding the safety issues. Inadequate
maintenance and safety procedures, lack of communication
between shift, faulty design and improper emergency response
and planning led to the catastrophe [1,3]. After Piper Alpha,
safety policies and regulations were developed and implemented
in United Kingdom.
The incidents of Flixborough (1974), Seveso (1976) and
Bhopal (1984) showed the world its catastrophic potential of
process industry that can cause harm to people and environment
[1]. Bhopal tragedy became the worst ever industrial accident
in the history. On 3rd December 1984 40 ton of highly toxic
methyl isocyanate (MIC) was released due to runway reaction
in MIC storage tank. Water was accidentally entered into the
MIC storage tank and reacted with MIC exothermally. This
caused runway reaction and produced excessive heat inside
the tank. Consequently, MIC was vaporized and released to the
atmosphere. The toxic exposure immediately killed over 2000
people of Bhopal due to respiratory distress [4] and caused a
significant increase of morbidity and thousands of premature
deaths in the subsequent years. The fundamental causes of the
incident were inadequate reactive hazard assessment, faulty
instruments and ineffective release management system [5].
Process Safety Management and Legislation
Bhopal incident was the wake-up call for the Indian
government. After the disaster, environmental policies and
regulation enacted including the Air Act (1987), the Hazardous
Waste (Management and Handling) Rules and the Environment
Protection (2nd Amendment) Rules 1992. The Bhopal incident
received widespread media attention and changed world view
on the importance of process safety issues. U. S Unions begin
to lobby for a Process Safety Standard. By investigating the
underline causes of major industrial incidents, OSHA proposed a
process safety management (PSM) standard for highly hazardous
chemicals in 1990. After an extensive public hearing and debate,
PSM standard was effective in 1992 aiming to prevent accidental
release of chemicals that could pose a threat to employees or
the environment. Seveso incident was main driver to develop
process safety regulations for European Union. EU process
safety management and legislations were introduced as Seveso I Directive (1982), Seveso II Directive (1996), later modified in
2003 and Seveso III Directive (2012).
Case Study: Effect of Deficiencies in Process Safety Management Program
Let’s look at the case of a recent incident at Williams
Geismar Olifins Plant, Geismar, Louisiana. A reboiler (shell &
tube heat exchanger) that supplied heat to distillation column
was catastrophically ruptured on 13th June 2013, causing a
boiling liquid expanding vapor explosion and fire. The incident
killed two operators and injured 167 individuals [6]. What went
wrong? In original design, two reboilers were continuously
in operation to feed the distillation unit. However, it requires
shutdown of the distillation unit for periodic maintenance and
cleaning due to fouling on the tube surface of the reboiler. For
reduction of process downtime, Willium decided to change the
process and installed new valves and piping in 2001 so that it
allows one reboiler at a time and the other can be kept standby
or ready to use. These changes introduced a new process hazard
as the additional valves isolated the reboiler from its relief valves
that located on the top of the distillation column.
On the day of the incident, Willium operators noticed the
flow rate of hot water in functioning reboiler was decreasing
last couple of days. It could be because of fouling. So operators
decided to switch the standby reboiler online. Unknown to the
operators the reboiler shell side process valve was closed and
blocked-in with partially filled liquid propane due to valve
leaking or inadvertent opening of a valve. When reboiler hot
water valves were opened, liquid propane inside the shell
begun to heat up. Due to thermal expansion of liquid propane,
a dramatic pressure rise within the shell caused boiling liquid
vapor explosion and fire. Process safety management program
weaknesses at Willium facility during 12 years led to the reboiler
to be unprotected from overpressure. These weaknesses include
deficiencies in implementing Management of Change (MOC),
Pre-Startup Safety Review (PSSR) and Process Hazard Analysis
(PHA). Chemical Safety Board investigated the incident and
identified a number of process safety management program
deficiencies that contribute to the incidents which includes
A. Willium didn’t perform adequate Management of
Change,B. Willium did perform three process hazard analysis during 2001 to 2013, but they didn’t implement the action items from PHAs or recommendation from a contracted pressure relief system engineering analysis
C. Willium didn’t assess the hazard before the start up of standby reboiler which was a crucial mistake. The incident of Willium facility could be avoided if they performed MOC appropriately, assessed the overpressure hazard and/or implemented the recommendation of PHAs. One of key lesson from the incident is that overpressure protection is essential for all pressure vessels and PHA team must need to ensure the effective overpressure protection system for all the pressure vessels in process industry.
Conclusion
Despite all the rules and regulations, chemical accidents
are still happening. The analysis of the past catastrophic
incident clearly indicates the lack of scientific and technical
competencies as well as deficiencies in managing safety issues.
Therefore, a three-way partnership is required from academia,
industry and the government. Academics from the universities/
research/training institutions should recognize the importance
of process safety to improve the technical competency level for
both practicing engineers and new graduates. The process safety
education should be integrated into the engineering curriculum.
The government regulatory authority should set a minimum
safety program requirements or standards for process industries.
The process industries should implement various programs
aiming to improve process safety management performance and
develop a good safety culture.
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