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6.0 RISK ASSESSMENT AND DISASTER MANAGEMENT PLAN
6.1 Introduction
Hazard analysis involves the identification and quantification of various hazards
(unsafe conditions) that exist in the plant. On the other hand, risk analysis deals
with the identification and quantification of risks, the plant equipment and personnel
are exposed to, due to accidents resulting from the hazards present in the plant.
In the sections below, the identification of various hazards, probable risks in the
plant, maximum credible accident analysis, and consequence analysis are addressed
which gives a broad identification of risks involved in the plant operations. Based on
the risk estimation disaster management plan has also been presented
6.2 Approach to the Study
Risk involves the occurrence or potential occurrence of some accident consisting of
an event or sequence of events. The risk analysis assessment study covers the
following:
Identification of potential hazard areas;
Identification of representative failure cases;
Visualization of the resulting scenarios in terms of fire (thermal radiation) and
explosion;
Assess the overall damage potential of the identified hazardous events and the
impact zones from the accidental scenarios;
Assess the overall suitability of the site from hazard minimization and disaster
mitigation points of view;
Furnish specific recommendations on the minimization of the worst accident
possibilities; and
Preparation of broad Disaster Management Plan (DMP), On-site and Off-site
Emergency Plan, which includes Occupational and Health safety plan.
6.3 Hazardous Chemical Storage at the Plant
The storage capacities of various fuels in the plant are given in Table-6.1. In the
proposed expansion few more storage tanks will add to the existing inventory.
TABLE-6.1
STORAGE CAPACITIES OF FUELS AND CHEMICALS IN PLANT
Sr. No.
Name of the Chemical Storage Capacity
(KL)
Type of Storage Classification of Storage
Tank
1 Toluene 45 KL Under Ground B
2 Acetone 46 KL Under Ground B
3 DNS 221 KL Under Ground B
4 Methanol 120 KL Under Ground B
5 Ethyl acetate 21 KL Under Ground B
6 DMF 6 KL Barrel B
7 Hexane 12 KL Barrel B
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Sr. No.
Name of the Chemical Storage Capacity
(KL)
Type of Storage Classification of Storage
Tank
8 THF 12 KL Barrel B
9 Pyridine 8 KL Barrel B
10 MTBE 16 KL Barrel B
11 MDC 34 KL Barrel B
12 Isopropanol 16 KL Barrel B
13 EDC 31 KL Under Ground B
A: Dangerous Petroleum B: Non- Dangerous Petroleum C: Heavy Petroleum
6.4 Hazard Identification
6.4.1 Introduction
Identification of hazards in plant is of primary significance in the analysis,
quantification and cost effective control of accidents involving chemicals and
process. A classical definition of hazard states that hazard is in fact the
characteristic of system/plant/process that presents potential for an accident.
Hence, all the components of a system/plant/process need to be thoroughly
examined to assess their potential for initiating or propagating an unplanned
event/sequence of events, which can be termed as an accident. The following two
methods for hazard identification have been employed in the study:
Identification of major hazardous units based on Manufacture, Storage and
Import of Hazardous Chemicals Rules, 1989 of Government of India (GOI Rules,
1989); as amended in 2000 and;
Identification of hazardous units and segments of plants and storage units based
on relative ranking technique, viz. Fire-Explosion and Toxicity Index (FE&TI).
6.4.2 Identification of Major Hazardous Units
6.4.2.1 Classification of Major Hazardous Substance
Hazardous substances may be classified into three main classes: Flammable
substances, Unstable substances and Toxic substances. The ratings for a large
number of chemicals based on flammability, reactivity and toxicity have been given
in NFPA Codes 49 and 345 M. Hazardous characteristics of the major flammable
materials and chemicals that are employed in different processes are listed in
Table-6.2.
TABLE-6.2
PROPERTIES OF FUELS/CHEMICALS USED
Chemical Type TLV
(mg/m3) FBP MP FP UEL LEL
°C % Toluene Flammable Liquid 50 ppm
(TWA) 110.4 -95 4 7.1 1.1
Acetone Flammable Liquid 1780 56.5 - 20 12.8 2.6 DNS Flammable Liquid Methanol Flammable Liquid 260 64.5 - 11.1 36.5 6.0 Ethyl acetate Flammable Liquid 1400 - -83 37.8 - -
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Chemical Type TLV (mg/m3)
FBP MP FP UEL LEL
°C % DMF Flammable Liquid 30 - 153 136 - - Hexane Flammable Liquid 176 - -95 -22.5 - - THF Flammable Liquid 599 - -108.3 -14.5 - - Pyridine Flammable Liquid - - - - - - MTBE Flammable Liquid - -109 -28 - - MDC Flammable Liquid 50 ppm
(TWA) -95 - - -
Isopropanol Flammable Liquid 1230 82 -88.5 11.66 12.0 2.0 EDC Flammable Liquid 40 83.5 -35 13.0 15.9 6.2
TLV : Threshold Limit Value FBP : Final Boiling Point MP : Melting Point FP : Flash Point UEL : Upper Explosive Limit LEL : Lower Explosive Limit
6.4.3 Identification of Major Hazard Installations Based on GOI Rules, 1989 (amended in
2000)
Following accidents in the chemical industry in India over a few decades, a specific
legislation covering major hazard activities has been enforced by Govt. of India in
1989 in conjunction with Environment Protection Act, 1986. This is referred here as
GOI rules 1989 (amended in 2000). For the purpose of identifying major hazard
installations the rules employ certain criteria based on toxic, flammable and
explosive properties of chemicals.
A systematic analysis of the fuels and their quantities of storage has been carried
out, to determine threshold quantities as notified by GOI Rules and the applicable
rules are identified.
6.4.4 Fire Explosion and Toxicity Index (FE&TI) Approach
Fire, Explosion and Toxicity Indexing (FE & TI) is a rapid ranking method for
identifying the degree of hazard. The application of FE&TI would help to make a
quick assessment of the nature and quantification of the hazard in these areas.
However, this does not provide precise information. Respective Material Factor (MF),
General Hazard Factors (GHF), Special Process Hazard Factors (SPH) are computed
using standard procedure of awarding penalties based on storage handling and
reaction parameters. For each separate plant process, which contains flammable or
toxic substances, a fire and explosion index F and/or a toxicity index T may be
determined in a manner derived from the method for determining a fire and
explosion index developed by the Dow Chemical Company.
6.4.4.1 FE and TI Methodology
Dow's Fire and Explosion Index (F and E) is a product of Material Factor (MF) and
hazard factor (F3) while MF represents the flammability and reactivity of the
substances, the hazard factor (F3), is itself a product of general process hazards
(GPH) and special process hazards (SPH). An accurate plot plan of the plant, a
process flow sheet and Fire and Explosion Index and Hazard Classification Guide
published by Dow Chemical Company are required to estimate the FE & TI of any
process plant or a storage unit.
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6.4.4.2 Computations and Evaluation of Fire and Explosion Index
The Fire and Explosion Index (F&EI) is calculated from -
)()(& SPHGPHMFEIF
The degree of hazard potential is identified based on the numerical value of F&EI as
per the criteria given below:
TABLE-6.3
HAZARD POTENTIAL IDENTIFICATION
F&EI Range Degree of Hazard
0-60
61-96
97-127
128-158
159-up
Light
Moderate
Intermediate
Heavy
Severe
6.4.4.3 Toxicity Index (TI)
The toxicity index is primarily based on the index figures for health hazards
established by the NFPA in codes NFPA 704, NFPA 49 and NFPA 345 m.
6.4.4.4 Classification of Hazard Categories
By comparing the indices F&EI and TI, the unit in question is classified into one of
the following three categories established for the purpose are presented in Table-
6.4.
TABLE-6.4
FIRE EXPLOSION AND TOXICITY INDEX
Category Fire and Explosion Index
(F&EI)
Toxicity Index (TI)
I F&EI < 65 TI < 6
II 65 < or = F&EI < 95 6 < or = TI < 10
III F&EI > or = 95 TI > or = 10
Certain basic minimum preventive and protective measures are recommended for
the three hazard categories.
7.4.4.5 Results of FE and TI for Storage/Process Units
Based on the GOI Rules, the hazardous fuels/chemicals used in the existing plant
were identified. Fire and Explosion are the likely hazards, which may occur due to
the fuel storages. Hence, Fire and Explosion index has been calculated for in plant
storage. Detailed estimates of FE&TI are given in Table-6.5.
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TABLE-6.5
FIRE EXPLOSION AND TOXICITY INDEX FOR STORAGE FACILITIES
Sr.
No.
Chemical Total Quantity
(KL)
F&EI Category TI Category
1 Toluene 45 KL 11.2 Light - -
2 Acetone 46 KL 21.1 Light - -
3 DNS 221 KL - -
4 Methanol 120 KL 9.3 Light - -
5 Ethyl acetate 21 KL 36.2 Light - -
6 DMF 6 KL 3.0 Light - -
7 Hexane 12 KL - Light - -
8 THF 12 KL - Light - -
9 Pyridine 8 KL - Light - -
10 MTBE 16 KL -
11 MDC 34 KL 11.2 Light - -
12 Isopropanol 16 KL 36.2 Light - -
13 EDC 31 KL 10.5 Light - -
6.5 Hazard Assessment and Evaluation
6.5.1 Introduction
Preliminary hazards analysis is based on the philosophy "PREVENTION IS BETTER
THAN CURE". How safe are the operations? Safety is relative and implies freedom
from danger or injury. But there is always some element of danger or risk in
anything we do or build. When a chemical process facility is considered safe? This
calls for identification of hazards, quantification of risk and further suggests hazard-
mitigating measures, if necessary.
6.5.2 Methodology
An assessment of the conceptual design is conducted for the purpose of identifying
and examining hazards related to feed stock materials, major process components,
utility and support systems, environmental factors, proposed operations, facilities
and safeguards.
6.5.3 Preliminary Hazard Analysis (PHA)
A preliminary hazard analysis is carried out initially to identify the major hazards
associated with storages and the processes of the proposed plant. This is followed
by consequence analysis to quantify these hazards. Finally, the vulnerable zones are
plotted for which risk reducing measures are deduced and implemented.
6.5.3.1 Fuel/Chemical Storage
In case of tank of fuel/chemical released in the dyke area catching fire, a steady
state fire will ensue. Failures in pipeline may occur due to corrosion and mechanical
defect. Failure of pipeline due to external interference is not considered as this area
is licensed area and all the work within this area is closely supervised with trained
personnel.
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TABLE-6.6
PRELIMINARY HAZARD ANALYSIS FOR PROCESS AND STORAGE AREAS
Sr.
No.
Blocks/Areas Hazards Identified
1 Boilers
Fire (mainly near oil burners), steam; Explosions, Fuel Explosions
2 Power Transformers Explosion and fire.
3 Switch-yard Control Room Fire in cable galleries and Switchgear/Control
Room.
4 Tank farms Fire
5 Incinerators Explosion and fire.
TABLE-6.7
PRELIMINARY HAZARD ANALYSIS FOR THE WHOLE PLANT IN GENERAL
PHA
Category Description of
Plausible Hazard
Recommendation Provision
Environmental
factors
If there is any
leakage and eventuality of source of
ignition.
-- All electrical fittings and
cables are provided as per the specified standards. All motor starters are
flame proof.
Highly
inflammable nature of the chemicals may cause fire hazard in the storage facility.
A well-designed fire
protection including protein foam, dry powder, CO2 extinguisher should be provided.
Fire extinguisher of small
size and big size are provided at all potential fire hazard places. In addition to the above, fire hydrant network is also provided.
6.5.4 Maximum Credible Accident Analysis (MCAA)
Hazardous substances may be released as a result of failures or catastrophes,
causing possible damage to the surrounding area. This section deals with the
question of how the consequences of the release of such substances and the
damage to the surrounding area can be determined by means of models. Major
hazards posed by flammable storage can be identified taking recourse to MCA
analysis. MCA analysis encompasses certain techniques to identify the hazards
and calculate the consequent effects in terms of damage distances of heat
radiation, toxic releases, vapor cloud explosion, etc. A host of probable or
potential accidents of the major units in the complex arising due to use, storage
and handling of the hazardous materials are examined to establish their
credibility. Depending upon the effective hazardous attributes and their impact on
the event, the maximum effect on the surrounding environment and the
respective damage caused can be assessed.
The reason and purpose of consequence analysis are many folds like:
Part of Risk Assessment;
Plant Layout/Code Requirements;
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Protection of other plants;
Protection of the public;
Emergency Planning; and
Design Criteria (e.g. loading on Control Room).
The results of consequence analysis are useful for getting information about all
known and unknown effects that are of importance when some failure scenario
occurs in the plant and also to get information as how to deal with the possible
catastrophic events. It also gives the workers in the plant and people living in the
vicinity of the area, an understanding of their personal situation.
6.5.4.1 Damage Criteria
The fuel storage and the supply pipelines may lead to fire and explosion hazards.
The damage criteria due to an accidental release of any hydrocarbon arise from fire
and explosion. Contamination of soil or water is not expected as these fuels will
vaporize slowly and would not leave any residue. The vapors of these fuels are not
toxic and hence no effects of toxicity are expected.
Fire Damage
A flammable liquid in a pool will burn with a large turbulent diffusion flame. This
releases heat based on the heat of combustion and the burning rate of the liquid. A
part of the heat is radiated while the rest is convicted away by rising hot air and
combustion products. The radiations can heat the contents of a nearby storage or
process unit to above its ignition temperature and thus result in a spread of fire. The
radiations can also cause severe burns or fatalities of workers or fire fighters located
within a certain distance. Hence, it will be important to know beforehand the
damage potential of a flammable liquid pool likely to be created due to leakage or
catastrophic failure of a storage or process vessel. This will help to decide the
location of other storage/process vessels, decide the type of protective clothing the
workers/fire fighters’ need, the duration of time for which they can be in the zone,
the fire extinguishing measures needed and the protection methods needed for the
nearby storage/process vessels. Table-6.8 presents the damage effect on
equipment and people due to thermal radiation intensity.
TABLE-6.8
DAMAGE DUE TO INCIDENT RADIATION INTENSITIES
Sr.
No.
Incident
Radiation (kW/m2)
Type of Damage Intensity
Damage to Equipment Damage to People
1 37.5 Damage to process equipment 100% lethality in 1 min. 1% lethality in 10 sec.
2 25.0 Minimum energy required to ignite wood at indefinitely long exposure without a flame
50% Lethality in 1 min. Significant injury in 10 sec.
3 19.0 Maximum thermal radiation
intensity allowed on thermally unprotected adjoining
equipment
-- --
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4 12.5 Minimum energy to ignite with a flame; melts plastic tubing
1% lethality in 1 min.
5 4.5 -- -- Causes pain if duration is longer than 20 sec, however blistering is un-likely (First
degree burns)
6 1.6 -- -- Causes no discomfort on long exposures
Source: Techniques for Assessing Industrial Hazards by World Bank
The effect of incident radiation intensity and exposure time on lethality is given in
Table-6.9.
TABLE-6.9
RADIATION EXPOSURE AND LETHALITY
Radiation Intensity
(kW/m2) Exposure Time
(seconds) Lethality (%) Degree of Burns
1.6 -- 0 No Discomfort even after long exposure
4.5 20 0 1st
4.5 50 0 1st
8.0 20 0 1st
8.0 50 <1 3rd
8.0 60 <1 3rd
12.0 20 <1 2nd
12.0 50 8 3rd
12.5 -- 1 --
25.0 -- 50 --
37.5 -- 100 --
6.5.5 Scenarios Considered for MCA Analysis
6.5.5.1 Modeling Scenarios
Based on the storage and consumption of all stored chemicals/fuels the following
failure scenarios in the plant have been identified for MCA analysis and the scenarios
are discussed in Table-6.10.
TABLE-6.10
SCENARIOS CONSIDERED FOR MCA ANALYSIS (EXISTING)
Sr. No. Failure of Fuel/Chemical Total Storage
Quantity (KL) Model Considered for
Assessment
1 Toluene 45 KL Pool Fire
2 Acetone 46 KL Pool Fire
3 DNS 221 KL Pool Fire
4 Methanol 120 KL Pool Fire
5 Ethyl acetate 21 KL Pool Fire
6 DMF 6 KL Pool Fire
7 Hexane 12 KL Pool Fire
8 THF 12 KL Pool Fire
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Sr. No. Failure of Fuel/Chemical Total Storage Quantity (KL)
Model Considered for Assessment
9 Pyridine 8 KL Pool Fire
10 MTBE 16 KL Pool Fire
11 MDC 34 KL Pool Fire
12 Isopropanol 16 KL Pool Fire
13 EDC 31 KL Pool Fire
6.5.5.2 Methodology
A perusal of Table-6.10 clearly indicates that the storage is flammable liquids. Fires
could occur due to presence of ignition source at or near the source of spill. Tank
fires may occur due to the following:
Ignition if rim seal leak leading to rim seal fire and escalating to full-fledged tank
fire. Lighting is a major source of ignition of tank fires.
Overflow from tank leading to spillage, vapor cloud formation and its subsequent
ignition, which flashes back to the tank leading to tank fire. The chance of
overflow should be less unless operator has grossly erred in receiving fuel into
the same tank. Spillage due to overflow may result in a dyke fire if ignition
occurs after sufficiently long period.
Sinking of floating roof: This may occur due to mechanical defect or due to
accumulation of rainwater in the roof, which is not drained.
For the present study, the scenarios under consideration assume that the peak level
of radiation intensity will not occur suddenly. Based on the past experience, it is
found that 20-30 minutes time will be required before a tank fire grows to full size.
For radiation calculations, pool fire has been considered. From the above
considerations, the criteria of 4.5 kW/m2 have been selected to judge acceptability
of the scenarios. The assumptions for calculations are:
It is not continuous exposure;
It is assumed that No fire detection and mitigation measures are initiated
There is not enough time available for warning the public and initiating
emergency action;
Secondary fire at public road and building is not likely to happen;
The effect of smoke on reduction of source radiation intensity has not been
considered; therefore hazard distances calculated tend to be conservative; and
Shielding effect of intervening trees or other structures has not been considered.
No lethality is expected from this level of intensity although burn injury takes
place depending on time of exposure.
Based on the above assumptions each storage facility have been assessed with
respect to Pool fires. The following assumptions are made for evaluating the risk on
the plant and personnel due to the failure scenarios.
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6.5.5.3 Properties of Fuels Considered for Modeling Scenarios (Pool fire)
The chemical data for various fuels used for modeling is tabulated in Table-6.11
and are compiled from various literature.
TABLE-6.11
PROPERTIES OF FUELS CONSIDERED FOR MODELING
Sr.
No.
Fuel Molecular Weight
g/mol
Boiling Point (oC) Density
Kg/m3
1 Toluene 92.14 110.6 3.1
2 Acetone 58.05 56 2.0
3 DNS 228.12 174 MP -
4 Methanol 34.04 64.7 1.11
5 Ethyl acetate 88.11 170.6 3.04
6 DMF 73.09 307.4 2.51
7 Hexane 86.18 154.4 2.97
8 THF (Tetra Hydro Furan) 72.11 65 2.5
9 Pyridine 79.1 115 0.97
10 MTBE 88.15 55.2 3.1
11 MDC 84.94 40 2.9
12 Isopropanol 60.1 82.6 2.07
13 EDC 98.96 84 3.4
6.5.6 Model Computations
6.5.6.1 Results and Discussion - Pool Fire
The results of MCA analysis are tabulated indicating the distances for various
damages identified by the damage criteria. Calculations are done for radiation
intensities levels of 37.5, 25, 19, 12.5, 4.5 and 1.6 kW/m2, which are presented in
Table-6.12 and in Figure-6.1 for different scenarios.
TABLE-6.12
OCCURRENCE OF VARIOUS RADIATION INTENSITIES- POOL FIRE
Radiation Quantity (KL) Radiation Intensities (kW/m2)/Distances (m)
37.5 25.0 12.5 4.5 1.6 Toluene 45 KL 42.0 52.9 78.6 140.7 253.6 Acetone 46 KL 43.5 54.8 81.4 145.7 262.6 Methanol 120 KL 75.7 95.4 141.6 253.5 457 Ethyl acetate 21 KL 29.3 36.9 54.8 98.0 176.8 DMF 6 KL 11.3 14.2 21.1 37.8 68.2 Hexane 12 KL 24.7 31.2 46.3 82.8 149.4 THF 12 KL 29.0 36.5 54.2 97 174.8 MTBE 16 KL 31.3 39.5 58.6 104.9 189 MDC 34 KL 42.1 53.0 78.7 140.8 253.9 Isopropanol 16 KL 31.8 40.1 59.5 106.5 192.0 EDC 31 KL 37.8 47.6 70.7 126.5 228.1
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FIGURE-6.1
RISK CONTOUR OF STORAGE AREAS
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7.5.6.2 Conclusions on Pool Fire
A review of modeling results clearly indicates that the maximum damage and
fatality would occur at <85 m distance. The radiation intensities would envelop the
storage tank and will be confined in and around the storage area.
The radiation intensities of 37.5 kW/m2 represent 100% lethality on people and
complete damage to the process equipment and minimum energy required to ignite
wood (without a flame) and melting of plastic. The equipment and the personal
falling within the distance computed for 37.5 kW/m2 would be damaged and 100%
fatality is likely to occur, which in-turn depends on the number of people working
within this vulnerable distance at that particular time.
A perusal of modeling results tabulated in Table-6.12 indicates that the
radiation intensity of 37.5 kW/m2 is likely to occur within a maximum distance
(range) of 75.7 m around the Methanol tank. But, all the tanks are not located
at a place, but with some distance. Therefore, if one tank gets fire and it will
affect adjacent tank.
The radiation intensity of 12.5 kW/m2 represents 1% lethality on people and
minimum energy required to ignite wood (with a flame) and melting of plastic.
The equipment and the personal falling within the distance computed for 12.5
kW/m2 would be partially damaged and 1% lethality is likely to occur, which in-
turn depends on the number of people working within this vulnerable distance
at that particular time.
A perusal of modeling results tabulated in Table-6.12 indicates that the
radiation intensity of 12.5 kW/m2 is likely to occur within a distance of 141.6
m, considering the Methanol tank is at an outer edge tank farm area. About 1%
lethality and partial damage depending on the type of equipment is likely to
occur within these distances.
As the storage tanks are provided with dyke, the fire would be confined within the
dyke wall. The frequency of such a bund fire, taking place is very low and is of the
order of 1 in 2000 to 4000 years for one tank rupture. It may be noted that the
occurrence of pool fire is rather rare but such data/discussions are useful for
emergency planning. There will be adequate time to evoke emergency planning
and evacuate people by the time a small fire in tank area can grow into a full
fledge bund fire.
6.6 Risk mitigation and management measures
6.6.1 Hierarchy of Controls
There are a number of ways to control the risks associated with hazardous
chemicals. Some control measures are more effective than others. Control
measures are ranked from the highest level of protection and reliability to the
lowest. This ranking is known as the hierarchy of control.
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The foremost effort has been to eliminate hazard as well as risk, and if not,
reasonable practicable risk is minimized by using one or more of the following
approaches
Substitution Isolation Engineering Controls
If the risk persists it is further minimized by administrative controls, and
further minimized with certain personnel protective equipments.
6.6.2 Eliminating the hazard
Elimination of hazardous work practices from the work places is the most
effective control measure before considering any control measures. Substituting a
less volatile material to control vapour hazard has been envisaged to maximum
extent, and use of any chemical in powder form is completely avoided. Wherever
feasible it is proposed to use less concentration of acid and alkalis.
6.6.2 Isolation of hazard
Isolation of hazard involves separating people from the chemicals or hazards by
distance or barriers to prevent or minimize exposure. Isolate workers from
chemicals, use of closed systems for transfer of chemical, use of glove boxes or
glove bags, installation of process units in closed enclosure fitted with
mechanical exhausts, and access restricted to properly protected personnel,
undertake operations under positive pressure to prevent air borne contaminants,
distancing workers from hazardous chemicals and any potential hazards
generated by their use. When storing chemicals on shelving or other storage
systems, hazardous chemicals will not be stored above or below other chemicals
or other things.
6.6.3 Engineering controls
Engineering controls are physical in nature involving usage of mechanical devices
or processes that eliminate, suppress or contain chemicals, or limit the area of
contamination in the event of spills and leaks. Installation of closed enclosures
and appropriate design of local exhaust ventilation system to eliminate air borne
contaminants.
Maintaining a safe atmosphere in the storage and handling area of hazardous
chemicals, and ensure no recirculation of air within the closed enclosure.
Provision of scrubber in the exhaust system to reduce airborne contaminants
which may be harmful to the environment or people prior to discharge to the
atmosphere.
Regular checks of exhaust system as in planned maintenance schedules to ensure
that vents remain unobstructed. Mechanical ventilation Inlet and outlet vents
located on opposite sides of the storage area at low levels provide airflow across
the floor.
For solvent storage areas, where heavier than air vapours may accumulate in
lower regions with a subsequent buildup of hazardous concentrations, vents
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provided at a level immediately above any spill containment, on the opposite
sides of a room to provide for airflow across the storage or handling area.
6.6.4 Administrative controls
Administrative controls are considered to supplement other control measures.
Administrative controls are extremely important for emergencies when other
control measures fail, such as for managing spills and leaks and are particularly
important for those workers who are required to clean up spills, or who carry out
regular cleaning and maintenance work.
There is well written policy and work procedures for safe work method, and also
reducing the number of workers exposed to the chemical as also reducing the
duration and/or frequency of workers’ exposure through specific work procedures
through job rotation, reducing quantities of hazardous chemicals through
inventory reduction and prompt disposal of hazardous chemicals that are no
longer required .
Implementation of procedures where only staff who are involved in the use,
handling, storage or generation of hazardous chemicals are allowed access to
high risk areas where there may be a greater risk of exposure , implementing
procedures to prevent introduction of ignition sources into hazardous areas .
Reducing the period of time in which a chemical could escape into the work area,
by minimizing the time that mixers, reactors are open to the environment both
during and after use)
Using vacuum wet methods to suppress dust that may be generated during dry
sweeping, keeping containers of hazardous chemicals tightly closed when not in
use, cleaning up spills immediately, prompt cleaning of residues from empty
containers that have held hazardous chemicals.
Prohibiting eating, drinking and smoking in potentially contaminated areas,
providing washing facilities for rinsing off chemicals (e.g. hand washing, safety
showers, laundering of clothes). Provision of Training and supervision to ensure
administrative controls are effectively implemented.
6.6.5 Personal Protective Equipment (PPE)
PPE are selected to minimize risk to health and safety, suitable for the nature of
the work and any hazard associated with the work, a suitable size and fit and
reasonably comfortable for the person wearing it, maintained, repaired or
replaced so it continues to minimize the risk , used or worn by the worker, so far
as is reasonably practicable.
A worker is ensured, so far as reasonably able, wear the PPE in accordance with
information, training or reasonable instruction. In most circumstances, PPE
includes overalls, aprons, footwear, gloves, chemical resistant glasses, face
shields and respirators. PPE is used to supplement higher level control measures.
The effectiveness of PPE relies heavily on workers following instructions and
procedures correctly. It is also imperative to observe workers, if PPE, is fit, is
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comfortable or is not a hindrance in the work. It will also be ensured to observe
workers after the task is complete to ensure that the PPE they have used is
stored and maintained correctly.
6.6.6 Specific control measures
This includes key control measures for managing risks from hazardous chemicals
in the workplace viz.,.
Use of water free vacuum generation using mechanical pumping system in a
closed circuit by means of dry pumping
Use of Surface heat exchangers
Us of pigging system in pipes using compressed air
Optimized equipment cleaning to prevent direct VOC release via openings
Often cleaning of equipment is finished with a final rinse of solvent. After addition
of solvent the vessel is cleaned by stirring or heating. Residual solvent is removed
by applying vacuum
Containment and Enclosure of sources
Elimination of openings
Use of vapor balancing
Use of circuits under nitrogen atmosphere for drying operation including
condenser for solvent recovery
Use of closed equipment for cleaning
Implementation of a Monitoring and Maintenance program
Us of pumps that designed to be tight
Use of double action mechanical seals and multiple sealing systems
Flanged joints will be used only where necessary with negligible leakage ratio
To ensure the airtightness of a vessel, all openings are checked and where
necessary sealed until the vessel keeps an applied pressure or vacuum and
pressure test carried out regularly
6.6.7 Keeping hazardous chemicals stable
As far as is reasonably practicable that hazardous chemicals do not become
unstable, decompose or change so as to create a hazard different to the hazard
originally created by the hazardous chemical or significantly increase the risk
associated with any hazard in relation to the hazardous chemical. Some
hazardous chemicals are inherently unstable or highly reactive, or they can
become unstable under certain conditions during use, often in a deliberate
process. This is mainly for hazardous chemicals that are dangerous goods,
however other hazardous chemicals may also present a risk if stability is not
maintained. To keep hazardous chemicals stable, manufacturer’s instructions are
followed, maintain specified proportions of ingredients, goods and other
components that constitute the hazardous chemicals.
Wherever appropriate, keep the hazardous chemicals within any control
temperature range where necessary, keep the hazardous chemical and the
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packaging dry, unless the packages themselves are impervious to moisture. This
does not apply where the hazardous chemicals are about to be used in a
manufacturing process. Some hazardous chemicals may provide an expiry date
on the label ,Where a chemical has passed its expiry date it should not be used,
but be disposed of in accordance with manufacturer’s instructions and local laws.
6.6.8 Impact Protection – Containers, Structures and Plant
To prevent damage from the movement of the structure or plant including any
attached pipe work or equipment, it would be ensured that structures or plant
used for the storage or handling of hazardous chemicals are appropriately located
and fixed to stable foundations. Impact protection measures are provided for
structures containing large quantities of hazardous chemicals, plant and
equipment including storage and process vessels, associated pipe work, pumps
and controls ,storage areas (including transit storage) for packages, and
associated shelves and racks „ exposed parts of the fire protection systems.
Containers are kept away from trafficable areas or prevent vehicle access.
Installation of crash protection measures, such as bollards and guardrails for
impact protection.
6.6.9 Containing spills
Wherever there is a risk of a spill or leak of a hazardous chemical in a solid or
liquid form, provision is made in each part of the workplace where a hazardous
chemical is used, handled, stored or generated for a spill containment system
that contains within the workplace any spill or leak of a hazardous chemical and
any resulting effluent. When a spill, leak or accidental release of hazardous
chemicals occurs, appropriate actions is taken to contain the hazardous chemicals
within the workplace. The spill containment system describes how to contain,
cleanup and dispose of the spill or leak and any resulting effluent.
Spill containment system will be large enough to ensure that all spills can be held
safely until cleaned up. A separate spill containment is provided for incompatible
goods.
The materials used to construct the containment system, as well as any materials
used for absorption, are compatible with the hazardous chemicals, other
materials in the vicinity that will prevent contamination of groundwater or soil,
the system’s integrity will be maintained in any reasonably foreseeable incident.
For large quantities of hazardous chemicals, bunding may be required. Bunding is
designed and constructed in accordance with the relevant Standard specific to the
type of hazardous chemical.
During the transfer process, avoiding spillage or overflow, including overflow
protection on equipment and receiving vessels „ providing emergency shut-offs to
limit the amount of hazardous chemicals released during a loss of containment „
providing a spill containment system „ reducing static electricity and vapour
generation. ensuring transfer fittings are compatible „ installing flow and pressure
regulators on pipe work or pumps „ installing interlocking of valves and switches „
implementing systems for detecting losses from pipe work and fittings, such as
static pressure loss detectors, measurement to determine losses in transfer or
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external sensors. Plumbed eye wash stations and safety showers will be installed
in areas where workers may be exposed in the event of a spill during transfer
operations.
Key considerations for safe storage and handling of gas cylinders include:
maintaining and regularly checking cylinders, regulators, hoses and pipes to
cylinders to ensure that there are no leaks or dents, storing cylinders in an
upright position to ensure the safety device functions correctly, securing cylinders
to prevent dislodgement, transport cylinders with appropriate equipment such as
trolleys or gas cages, keep the cylinder valve closed when the cylinder is not
being used, keep all sources of heat and ignition away from gas cylinders, even if
the cylinders do not contain flammable material, store cylinders outdoors or in
very well ventilated areas. Gas cylinders will be fitted with a bursting disc safety
device. If a small leak occurs, the cylinder valve will be closed if it is safe to do
so. Appropriate personal protective equipment will be put on before attempting to
locate the leak point.
For toxic gases, self-contained breathing apparatus will be used for emergency
use. The area will be well ventilated and air conditioning systems will turned off to
avoid spreading gas. However, if a large amount of gas escapes, the area will be
evacuated. If it is safe to do so, before evacuating, ventilate the area and remove
or isolate ignition sources. Contact the gas supplier for advice, or in an
emergency, contact the emergency services authority.
asphyxiation include: avoiding work being carried out in oxygen-depleted (under
19 per cent) atmospheres - for example this could be done by testing the
workplace atmosphere using an approved and intrinsically-safe gas monitor,
keeping the work area well-ventilated, particularly in low-lying areas and roof
spaces where gases can accumulate – this could be done by ensuring windows
are open where necessary and ventilation and extraction systems are on and are
fully functional, purging, using an air-supplied respirator, particularly in confined
spaces, checking cylinders, cylinder fittings, hoses and connections to ensure that
they are not damaged or in poor condition – this might include checking fittings
and hoses for signs of corrosion or degradation or spraying them with a small
amount of detergent solution or leak-detection spray and looking for bubble
formations which may indicate the presence of a gas leak.
6.6.10 Maintaining control measures
It must be ensure that the implemented control measures remain effective. This
includes checking that the control measures are fit for purpose; suitable for the
nature and duration of the work and are installed and used correctly. Maintenance
of control measures may involve the following: regular inspections of control
measures, supervision to ensure workers are using the control measures
properly, preventative maintenance and testing programs for chemical storage
and handling systems, periodic air monitoring to ensure that engineering and
administrative controls remain effective. Maintenance procedures will include
mechanisms for workers to report defective control measures as soon as they are
identified so that prompt remedial action can be taken.
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6.6.11 Preventative Maintenance and Integrity Testing
It must be ensured, so far as is reasonably practicable, that a system used at the
workplace for the use, handling or storage of hazardous chemicals is used only
for the purpose for which it was designed, manufactured, modified, supplied or
installed and is operated, tested, maintained, installed, repaired and
decommissioned having regard to the safety or workers and other persons at the
workplace.
Systems for the storage and handling of hazardous chemicals generally require
on-going maintenance and testing to ensure that they continue to be safe for the
intended use and that they maintain their operational integrity. Such systems
include, but are not limited to, reaction vessels, chemical transfer lines, pumps,
spill bunding and storage tanks, filters etc. To ensure that the integrity of
chemical handling systems is preserved, planned maintenance programs be
designed and carried out at regular intervals, consistent with manufacturer’s
instructions or advice provided by other competent persons. If this is not
reasonably practicable, inspections and maintenance should be carried out
annually.
Inspection of glass linings on steel or metal alloy reaction vessels to ensure there
are no cracks or holes which might allow contact of incompatible materials with
the metal vessel. Regular checking of bursting (rupture) discs and pressure-relief
systems on pressure vessels to ensure they have not “blown” and are of the
correct pressure rating for the work being performed. Bursting or rupture discs
are safety features of cylinders that prevent damage or injury from over-
pressurization. Checking spill bunding walls for cracks or other signs of wear to
ensure that, in the event of a spill, the bunding will not leak or fail. Checking for
signs of corrosion or degradation on tanks, pipework and compressed gas fittings.
If preventative maintenance checks show that the integrity of any chemical
handling system is in doubt or not performing as it is intended, repair or
replacement of the faulty system should be carried out as soon as practicable and
before its next use.
6.6.12 Providing information, training, instruction and supervision
It must be ensured that information, training and instruction provided to a
worker is suitable and adequate having regard to: „ the nature of the work
carried out by the worker „ the nature of the risks associated with the work at the
time the information, training or instruction is provided, and „ the control
measures implemented. Must also provide any supervision necessary to protect
workers from health and safety risks arising from the work at the workplace, if
the worker: „ uses, handles, generates or stores a hazardous chemical „ operates,
tests, maintains, repairs or decommissions a storage or handling system for a
hazardous chemical, or „ is likely to be exposed to a hazardous chemical.
Information, training, instruction and supervision must be provided not only to
workers but to other persons at the workplace such as visitors. Information,
training and instruction should include the following: the nature of the hazardous
chemicals involved and the risks to the worker, the control measures
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implemented, how to use and maintain them correctly, for example how and
when to clean or replace filters, the arrangements in place to deal with
emergencies, including evacuation procedures, containing and cleaning up spills
and first aid instructions, the selection, use, maintenance and storage of any
personal protective equipment (PPE) required to control risks and the limitations
of the PPE, any health monitoring which may be required and the worker’s rights
and obligations, the labelling of containers of hazardous chemicals, the
information that each part of the label provides and why the information is being
provided.
The work practices and procedures to be followed in the use, handling,
processing, storage, transportation, cleaning up and disposal of hazardous
chemicals. Information, training and instruction must be provided in such a way
that it is easily understood.
6.6.13 Health monitoring
it must be ensure health monitoring is provided to a worker carrying out work for
the business or undertaking if: the worker is carrying out ongoing work using,
handling generating or storing hazardous chemicals and there is a significant risk
to the worker’s health because of exposure to a hazardous chemical, and either
valid techniques are available to detect the effect on the worker’s health or a
valid way of determining biological exposure to the hazardous chemical is
available and it is uncertain, on reasonable grounds whether the exposure to the
hazardous chemical has resulted in the biological exposure standard being
exceeded. Health monitoring of a person means monitoring the person to identify
changes in the person’s health status because of exposure to certain substances.
It involves the collection of data in order to evaluate the effects of exposure and
to confirm that the absorbed dose is within safe levels. This allows decisions to be
made about implementing ways to eliminate or minimize the worker’s risk of
exposure, for example, reassigning to other duties that involve less exposure or
improving control measures.
If the results indicate that a worker is experiencing adverse health effects or signs
of exposure to a hazardous chemical, the control measure must be reviewed and
if necessary revised. inform workers and prospective workers about health
monitoring requirements, ensure health monitoring is carried out by or under the
supervision of a registered medical practitioner with experience in health
monitoring, consult workers in relation to the selection of the registered medical
practitioner, pay all expenses relating to health monitoring, provide certain
information about a worker to the registered medical practitioner, take all
reasonable steps to obtain a report from the registered medical practitioner as
soon as practicable after the monitoring has been carried out, provide a copy of
the report to the worker and the regulator if the report contains adverse test
result or recommendations that remedial measures should be taken. Also provide
the report to all other persons conducting a business or undertaking who have a
duty to provide health monitoring for the worker
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