CH 3

Industrial Safety & Maintenance
Tsegay G.
Department of Chemical Engineering

tsegay.gebrekidan@mu.edu.et
April 11, 2017
Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 1 / 44

Outline
1 Protective and Preventive Methods in Hazard Controls

Hazard Controls
Preventive Maintenance
Occupational Health Program
Emergency Planning
2 Industrial hygiene, reliability and risk analysis

Industrial Hygiene: Identification
Industrial Hygiene: Evaluation
Industrial Hygiene: Control
Risk Analysis:

Hazard Control
Some control measures are more effective than others at reducing the
hazard.
Be aware of the different types of controls available and the benefits
and limitations of each.
The first consideration for controlling hazards is to eliminate the haz-
ard or substitute a less hazardous material or process.
An example of this method is utilizing a water-based paint rather
than a solvent-based paint.
This control measure minimizes flammable vapors as well as eliminates
health concerns associated with solvent-based paints.
When it is not possible to eliminate a hazard, the hazard control should

be using the following methods (in order):
1 Engineering controls
2 Administrative controls
3 Personal Protective Equipment
Cont
Applying this hierarchy is a systematic approach to identify the most
effective method of risk reduction.
Hazard Control - Engineering
If hazard elimination or substitution is not feasible, engineering con-
trols should be considered next.
Engineering controls are physical changes to the work area or process
that effectively minimize a workers exposure to hazards.
Enclosed Hazard
Enclosure of the hazard, such as enclosures for noisy equipment.
Isolate Hazard
Isolation of the hazard with interlocks, machine guarding, welding cur-
tains, and other mechanisms.
Remove/Redirect Hazard
Removal or redirection of the hazard such as with local and exhaust
ventilation.

Redesign Workplace
Redesign of workstation to minimize ergonomic injuries.
If engineering controls are not feasible you must then consider
implementing administrative controls.
Administrative controls
No physical changes
Limits daily exposure to hazards by
Adjusting work tasks or schedules.
Examples of administrative controls include:
Limited time exposure to hazards
Written operating procedures,
Work practices
Safety and health rules for employees.
Alarms, signs and warnings
Buddy system
Training
Stretching exercises and break policies

Personal Protective Equipment (PPE):
Used when hazards cannot be eliminated through engineering or ad-
ministrative controls,
Must consider PPE necessary for employee protection
According to OSHA, PPE is acceptable as a control method in the
following situations:

Engineering controls do not eliminate hazard

While engineering controls are being developed

Administrative controls and safe work practices are not sufficient protec-
tion, and

tion, and
During emergencies.
The most effective control measure = all three hazard control
types.

tion, and
During emergencies.
The most effective control measure = all three hazard control
types.
For example, consider an operation that generates silica dust.
A ventilation system may be installed to control dust (engineering con-
trol),
Employees are trained and a sign is posted to warn employees of dangers
(administrative controls) and
Goggles are required to operate the equipment (PPE).
Cont

A breakdown of equipment in your facility may cause hazards.

For example,
A pump that fails during the process of delivering hazardous materials
through your production facility may create a hazardous condition.
The best way to prevent breakdowns or failures is to monitor and main-
tain your equipment regularly. Determine what hazards could occur
if your equipment is not maintained properly and plan to detect failures
before they occur.
To ensure your equipment is safe, implement a written preventive
maintenance program, which consists of a schedule of routine main-
tenance and monitoring. Include both safety and non-safety equipment
in your program.
Safety Equipment Examples. A confined space entry gas monitor
requires regular calibration to ensure that it can effectively detect the
gases in the atmosphere.

Cont
Determine the intervals required to maintain your equipment opera-

tional based on the manufacturers recommendation as well as your
experience with the equipment and good management practices.

Cont

Non-Safety Equipment Example.
Forklifts in your facility have daily and annual inspection requirements.
If there is any deterioration in the hydraulic cylinders or tires the capacity

rating reduces and there may be a failure during a lift.
Establish a regular inspection on a preventive maintenance schedule to

keep these devices operating safely.

Cont

Non-Safety Equipment Example.
Forklifts in your facility have daily and annual inspection requirements.
If there is any deterioration in the hydraulic cylinders or tires the capacity

rating reduces and there may be a failure during a lift.
Establish a regular inspection on a preventive maintenance schedule to

keep these devices operating safely.
When developing systems, be sure to include one for Disciplinary ac-
tions that cover all (employees, and contractors)
Ensure that it is applied consistently
Hazard Correction tracking - hazards that have been identified must
be tracked in order to eliminate and implement controls
Manage change
A management of change program ensures that any modifications
or additions to your equipment or processes are understood and con-
trolled, and includes:
Updating relevant building or equipment drawings,
Modifying safety procedures, and
Training employees on the changes.
Such a program is required for processes that utilize highly hazardous
chemicals that are subject to the OSHA Process Safety Management
program.
However, this program is beneficial for all changes in your business,
even if OSHA doesnt require it.
Conduct an analysis of new equipment and processes
Develop a system to conduct:
Comprehensive survey, or
Other worksite analysis technique on new equipment or processes
Implement appropriate controls before being placed into service
Example:
Suppose your business introduces a new raw material into the production
process. You must consider the following:

Example:
Suppose your business introduces a new raw material into the production
process. You must consider the following:
How the material will be stored and handled
What PPE may be required if engineering or administrative controls
are not effective at controlling exposures
If appropriate eyewash and safety showers are available, and
How to train your employees..

Occupational health program
An occupational health program allows the company to respond ef-

fectively to workplace injuries and illnesses and to monitor potential
health problems.
Medical Services & First Aid
The company must make available physician services, first aid to its em-
ployees. This does not mean that the company must provide health
care, but the company is expected to get medical help when medical
conditions arise from work-related events.
Medical Screening
Some OSHA standards require medical screening of employees. Medical
screening monitors if exposure to a hazard leads to a potential decline
in health.
An example is exposure to noise and the Hearing Conservation Program.

Cont
Employee Medical Records

The maintenance and confidentiality of employee medical records are
crucial.
According to OSHA, the company must maintain an employees medical
records for the duration of employment plus 30 years.
Records include employment medical questionnaires or histories, results
of laboratory tests or medical screening, or physicians opinions from
work-related injuries or illnesses.
Develop a system to maintain these records and to ensure that they are
kept in confidence.
Wellness Program
In your occupational health program, consider including health and well-
ness programs for your employees.
Smoking cessation programs, diet and nutrition education, and physical
fitness programs are examples of programs that encourage employees to
lead a healthy lifestyle, which helps them be healthy for work

Emergency Planning
Effective planning for emergencies and non-routine events is another

mechanism of controlling hazards and avoiding employee injuries.
Written Emergency Plan
Determine the actions that employees will take in the event of a fire,
chemical release or natural disaster.
Keep in mind those employees with disabilities, language barriers and
limited literacy.
Develop the written plan and train your employees prior to an emergency.
Dont forget unexpected events such as terrorist acts or workplace vio-
lence.
List emergency contacts and ensure the document is updated regularly
to reflect current personnel.

Cont
Emergency Eyewash and Safety Showers

Install emergency eyewash and safety showers where chemicals are used
or stored to provide quick flushing if an employee is exposed to the
chemical.
Pay close attention to areas such as battery charging stations, mainte-
nance operations, and laboratories where corrosive materials are often
used and require prompt flushing to prevent significant skin or eye dam-
age.
Include these units in your preventive maintenance program. Its impor-
tant to inspect and flush the units regularly to verify operation and to
ensure the water lines are clear of debris prior to emergency use.
Emergency Drills
Practice the elements of your emergency action plan by conducting reg-
ular fire and/or natural disasters drills.
Ensure that employees know how to evacuate buildings, where to take
shelter and who will take headcounts.

Cont
Emergency Contacts
Post emergency numbers at centrally located bulletin boards and update
the list regularly to reflect current personnel.
Ensure that employees who will operate critical equipment following an
emergency are properly trained.
Local Emergency Responders
Coordinate your emergency planning with the local emergency respon-
ders, such as the fire department and/or hazardous materials teams.
Invite them to your facility to teach them your specific worksite hazards
and to improve the emergency response time.

Outline
1 Protective and Preventive Methods in Hazard Controls

Hazard Controls
Occupational Health Program
Emergency Planning
2 Industrial hygiene, reliability and risk analysis

Risk Analysis:

Industrial hygiene
Industrial hygiene is a science devoted to the identification, evaluation,

and control of occupational conditions that cause sickness and injury.
Industrial hygienists are responsible for selecting and using instru-
mentation to monitor the workplace during the identification and con-
trol phases of industrial hygiene projects.
The three phases in any industrial hygiene project are identification,
evaluation, and control:
1 Identification: determination of the presence or possibility of workplace
exposures.
2 Evaluation: determination of the magnitude of the exposure.
3 Control: application of appropriate technology to reduce workplace ex-
posures to acceptable level
Key factors:
Employee exposure to hazards
Control for hazards to protect workers
Cont
In chemical plants and laboratories the industrial hygienist works closely

with safety professionals as an integral part of a safety and loss
prevention program.
After identifying and evaluating the hazards, the industrial hygienist

makes recommendations relevant to control techniques.
The industrial hygienist, safety professionals, and plant operations

personnel work together to ensure that the control measures are applied
and maintained.
It has been clearly demonstrated that toxic chemicals can be handled

safely when principles of industrial hygiene are appropriately applied.

One of the major responsibilities of the industrial hygienist
is to identify and solve potential health problems within
plants.
Chemical process technology, however, is so complex that this task

requires the concerted efforts of industrial hygienists, process designers,
operators, laboratory personnel, and management.
Many hazardous chemicals are handled safely on a daily basis within

chemical plants.
To achieve this operating success, all potential hazards must be identified

and controlled.
When toxic and/or flammable chemicals are handled, the potentially

hazardous conditions may be numerous in large plants there may be
thousands.
Cont
To be safe under these conditions requires discipline, skill, concern, and
attention to detail.
The identification step requires a thorough study of the chemical process,

operating conditions, and operating procedures.
The sources of information include process design descriptions,

operating instructions, safety reviews, equipment vendor
descriptions, information from chemical suppliers, and information from
operating personnel.
The quality of this identification step is often a function of the number of

resources used and the quality of the questions asked.
Resources for evaluating the hazards and developing control methods are
allocated on a priority basis, giving the appropriate time and attention to
the most significant hazards.
Material Safety Data Sheets
One of the most important references used during an industrial hygiene
study involving toxic chemicals is the material safety data sheet (MSDS).

Cont

Cont
A sample MSDS is shown in Figure1 3-2. The MSDS lists the physical
properties of a substance that may be required to determine the potential
hazards of the substance.
MSDSs are available from

1 the chemical manufacturer,
2 a commercial source, or
3 a private library developed by the chemical plant.
The industrial hygienist or safety professional must interpret the physical
and toxicological properties to determine the hazards associated with a
chemical.
These properties are also used to develop a strategy for the proper control
and handling of these chemicals.
1
Chemical Process Safety
Example: A survey of a laboratory is made and the following chemical
species are identified: Sodium chloride, toluene, hydrochloric acid, phenol,
sodium hydroxide, benzene, and ether. Identify the potential hazards in
this laboratory.

The evaluation phase determines the extent and degree of employee

exposure to toxicants and physical hazards in the workplace environment.
During the evaluation phase, the various types of existing control measures
and their effectiveness are also studied.
During the evaluation study, the likelihood of large and small leaks must
be considered.
Sudden exposures to high concentrations, through large leaks, may lead to

immediate acute effects. such as unconsciousness, burning eyes, or fits
of coughing.
Chronic effects, however, arise from repeated exposures to low

concentrations, mostly by small leaks.

Cont
Many toxic chemical vapors are colorless and odorless (or the toxic
concentration might be below the odor threshold).
Small leaks of these substances might not become obvious for months or
even years.
Special attention must be directed toward preventing and controlling low

concentrations of toxic gases.
In these circumstances some provision for continuous evaluation is

necessary; that is, continuous or frequent and periodic sampling
and analysis is important.
To establish the effectiveness of existing controls, samples are taken to

determine the workers exposure to conditions that may be harmful.

Cont
If problems are evident, controls must be implemented immediately;

temporary controls such as personal protective equipment can be
used. Longer term and permanent controls are subsequently developed.
After the exposure data are obtained, it is necessary to compare actual

exposure levels to acceptable occupational health standards, such as
TLVs2 , PELs3 , or IDLH4 concentrations.
These standards together with the actual concentrations are used to

identify the potential hazards requiring better or more control measures.
2
Threshold limit values
3
permissible exposure level
4
immediately dangerous to life and health
Evaluating exposures to volatile toxicants by monitoring
A direct method for determining worker exposures is by continuously

monitoring the air concentrations of toxicants on-line in a work
environment.
For continuous concentration data C(t) the TWA (time-weighted average)

concentration is computed using the equation
Z tw
TWA = C (t)dt (1)
0
Where
C(t) is the concentration (in ppm or mg/m3 ) of the chemical in the air
and tw , is the worker shift time in hours.
The integral is always divided by 8 hours, independent of the length of

time actually worked in the shift.

Cont
Thus, if a worker is exposed for 12 hours to a concentration of chemical

equal to the TLV-TWA, then the TLV-TWA has been exceeded, because
the computation is normalized to 8 hours.
Continuous monitoring is not the usual situation because most facilities do

not have the necessary equipment available.
The more usual case is for intermittent samples to be obtained,

representing worker exposures at fixed points in time.
If we assume that the concentration Ci is fixed (or averaged) over the

period of time Ti , the TWA concentration is computed by
C1 T1 + C2 T2 + ..... + Cn Tn
TWA = (2)
8hrs

Cont
All monitoring systems have drawbacks because
1 the workers move in and out of the exposed workplace and
2 the concentration of toxicants may vary at different locations in the
work area.
Industrial hygienists play an important role in the selection and placement
of workplace monitoring equipment and the interpretation of the data.
If more than one chemical is present in the workplace, one procedure is to

assume that the effects of the toxicants are additive (unless other
information to the contrary is available).
The combined exposures from multiple toxicants with different TLV-TWAs

is determined from the equation
n
X Ci
(3)
i=1
(TLV TWA)i

Cont
where
n is the total number of toxicants,
Ci is the concentration of chemical i with respect to the other toxicants,
and
(TLV-TWA)i , is the TLV-TWA for chemical species i.
If the sum in Equation 3 exceeds 1, then the workers are over exposed.
The mixture TLV-TWA can be computed from

Pn
i=1 Ci
(TLV TWA)mix = Pn Ci
(4)
i=1 (TLV TWA)i
If the sum of the concentrations of the toxicants in the mixture exceeds

this amount, then the workers are overexposed.
For mixtures of toxicants with different effects (such as an acid vapor

mixed with lead fume) the TLVs cannot be assumed to be additive.
Examples
1 Air contains 5 ppm of diethylamine (TLV-TWA of 10 ppm), 20 ppm of
cyclohexanol (TLV-TWA of 50 ppm), and 10 ppm of propylene oxide
(TLV-TWA of 20 ppm). What is the mixture TLV-TWA and has this
level been exceeded?

Examples
2 Determine the 8-hr TWA worker exposure if the worker is exposed to
toluene vapors as follows: (TLV for toluene = 100 ppm)
Duration of exposure (hr) Measured concentration (ppm)
2 110
2 330
4 90

Examples
2 Determine the 8-hr TWA worker exposure if the worker is exposed to
toluene vapors as follows: (TLV for toluene = 100 ppm)
Duration of exposure (hr) Measured concentration (ppm)
2 110
2 330
4 90
3 Determine the mixture TLV at 25 O C and 1 atm pressure of a mixture
derived from the following liquid:
Component Mole percent Species TLM(ppm)
Heptane 50 400
Toluene 50 50
Evaluation of Worker Exposures to Dusts
Industrial hygiene studies include any contaminant that may cause health
injuries; dusts, of course, fit this category.
Toxicological theory teaches that dust particles that present the greatest
hazard to the lungs are normally in the respirable particle size range of
0.2-0.5 m.
Particles larger than 0.5 m are usually unable to penetrate the lungs,
whereas those smaller than 0.2 m settle out too slowly and are mostly
exhaled with the air.
The main reason for sampling for atmospheric particulates is to estimate

the concentrations that are inhaled and deposited in the lungs.
Dust evaluation calculations are performed in a manner identical to that

used for volatile vapors. Instead of using ppm as a concentration unit,
mg/m3 or mppcf (millions of particles per cubic foot) is more convenient.
Example
1 Determine the TLV for a uniform mixture of dusts containing the fol-
lowing particles:
Type of dust Concentration (wt.%) TLV (mppcf)
Nonasbestiform talc 70 20
Quartz 30 2.7

After potential health hazards are identified and evaluated, the appro-
priate control techniques must be developed and installed.
This requires the application of appropriate technology for reducing
workplace exposures.
The types of control techniques used in the chemical industry are illus-
trated in Table 1.
Designing control methods is an important and creative task.
During the design process, the designer must pay particular attention
to ensure that the newly designed control technique provides the de-
sired control and that the new control technique itself does not create
another hazard, sometimes even more hazardous than the original prob-
lem.
The two major control techniques are environmental controls and
personal protection.

Type and explanation Typical techniques
Enclosures
Enclose room or equipment and Enclose hazardous operations such as sample points.
place under negative pressure. Seal rooms, sewers, ventilation, and the like.
Use analyzers and instruments to observe inside equipment.
Shield high-temperature surfaces.
Pneumatically convey dusty material.
Local ventilation
Contain and exhaust hazardous Use properly designed hoods.
substances. Use hoods for charging and discharging.
Use ventilation at drumming station.
Use local exhaust at sample points.
Keep exhaust systems under negative pressure.
Dilution ventilation
Design ventilation systems to Design locker rooms with good ventilation and special areas
control low-level toxics. or enclosures for contaminated clothing.
Design ventilation to isolate operations from rooms and offices.
Design filter press rooms with directional ventilation.
Wet methods
Use wet methods to minimize Clean vessels chemically vs. sandblasting.
contamination with dusts. Use water sprays for cleaning.
Clean areas frequently.
Use water sprays to shield trenches or pump seals.
Good housekeeping
Keep toxicants and dusts contained. Use dikes around tanks and pumps.
Provide water and steam connections for area washing.
Provide lines for flushing and cleaning.
Provide well-designed sewer system with emergency
containment
Personal protection
As last line of defense. Use safety glasses and face shields.
Use aprons, arm shields, and space suits.
Wear appropriate respirators; airline respirators are required
when oxygen concentration is less than 19.5%.
Table: Chemical Plant Control Techniques

Cont
Environmental control reduces exposure by reducing the concentration

of toxicants in the workplace environment.
This includes enclosure, local ventilation, dilution ventilation, wet

methods, and good housekeeping.
Personal protection prevents or reduces exposure by providing a barrier

between the worker and the workplace environment. This barrier is usually
worn by the worker, hence the designation "personal." Typical types of
personal protective equipment are listed in Table 3-10.

Cont

Reading Assignment
Respirators
Ventilation
Local Ventilation
Dilution Ventilation

Risk Analysis:
Hazard: something with the potential to cause harm.
Risk: the likelihood of occurrence and the magnitude of consequences of a

specified hazard being realized.
Risk Analysis:
analytical process to provide information regarding undesirable events;
process of estimating probabilities and expected consequences for iden-
tified risks.
detailed examination including risk assessment, risk evaluation and risk
management alternatives, performed to understand the nature of un-
wanted outcome;

Cont
Risk Analysis: A process undertaken to deal with matters which pose a
potential danger, managed according to certain standard procedure and
according to certain standard procedure and that involves:
Hazard Identification: Identification of the hazard (something poten-
tially harmful) in the given context.
Risk Assessment:The process of evaluating the risk resulting from a
hazard. Risk assessment is only part of the whole process of risk anal-
ysis.
Risk Management:
Based on the results of the risk assessment and the judgement of the
risk managers, decisions are taken and policy is formulated.
Risk management is the process of weighting policy alternatives in con-
sultation with all interested parties considering risk assessment and other
factors.
Risk Communication: Information exchange between risk assessors, risk
managers and those affected by both the risk and the decisions taken
before the final policy decisions are taken.
THANK YOU

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Industrial Safety & Maintenance

Department of Chemical Engineering

April 11, 2017

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 1 / 44

1 Protective and Preventive Methods in Hazard Controls

2 Industrial hygiene, reliability and risk analysis

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 2 / 44

When it is not possible to eliminate a hazard, the hazard control should

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 4 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 5 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 6 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 6 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 6 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 6 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 6 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 7 / 44

A breakdown of equipment in your facility may cause hazards.

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 8 / 44

Determine the intervals required to maintain your equipment opera-

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 9 / 44

Determine the intervals required to maintain your equipment opera-

If there is any deterioration in the hydraulic cylinders or tires the capacity

Establish a regular inspection on a preventive maintenance schedule to

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 9 / 44

Determine the intervals required to maintain your equipment opera-

If there is any deterioration in the hydraulic cylinders or tires the capacity

Establish a regular inspection on a preventive maintenance schedule to

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 11 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 11 / 44

An occupational health program allows the company to respond ef-

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 12 / 44

Employee Medical Records

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 13 / 44

Effective planning for emergencies and non-routine events is another

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 14 / 44

Emergency Eyewash and Safety Showers

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 15 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 16 / 44

1 Protective and Preventive Methods in Hazard Controls

2 Industrial hygiene, reliability and risk analysis

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 17 / 44

Industrial hygiene is a science devoted to the identification, evaluation,

In chemical plants and laboratories the industrial hygienist works closely

After identifying and evaluating the hazards, the industrial hygienist

The industrial hygienist, safety professionals, and plant operations

It has been clearly demonstrated that toxic chemicals can be handled

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 19 / 44

Chemical process technology, however, is so complex that this task

Many hazardous chemicals are handled safely on a daily basis within

To achieve this operating success, all potential hazards must be identified

When toxic and/or flammable chemicals are handled, the potentially

The identification step requires a thorough study of the chemical process,

The sources of information include process design descriptions,

The quality of this identification step is often a function of the number of

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 22 / 44

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 23 / 44

MSDSs are available from

Tsegay G. (EiT-M) Industrial Safety & Maintenance April 11, 2017 25 / 44