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CDB2012
Health, Safety andEnvironment
Heat, Temperatureand Pressure Hazards
Lecture 8Dr. Abrar Inayat
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Identify the information on heat, temperature and pressure hazards at workplace.
To overcome the hazards associated with theextreme heat, temperature and pressures.
OBJECTIVE
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Part I:Heat and Temperature Hazards
Part II:
Pressure Hazards
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Part I:
Heat and Temperature Hazards
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HEAT AND TEMPERATURE HAZARDS
Operations with high potential of causing heatstress normally involve high temperatures, radiantheat sources, high humidity, direct physical contactwith hot objects.
The American Conference of Government Industrialhygienists 1992 (ACGIH) states that workers shouldnot be permitted to work when their deep bodytemperature exceeds 38C.
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Example :
Iron and steel foundry
Electrical utilities (boiler room)
Bakeries , food canneries
Chemical plants
Construction, refining, asbestos removal
Hazardous waste site (require wearingimpermeable protective clothing)
POTENTIAL HEAT STRESSOPERATION
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DEFINITIONS
Temperature The degree of hotness or coldness ofa body or environment (corresponding to itsmolecular activity) that can be measured using athermometer.
Heat A form of energy that can be transferred fromone system to another system as a result oftemperature difference (from high to lowtemperatures).
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WET BULB GLOBE THERMOMETER(WBGT)
Most accurate measurement of heat hazards
Takes into account humidity, radiant heat and airtemperature
Reading lower than regular thermometer Testing should be done under normal working
conditions as close to the work as possible
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BODYS RESPONSE TO HEAT
Factors affecting Heat Stress:
Intensity of the heat
Duration of the exposure period
Tasks involved
Person performing the tasks
Presence of other stresses
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CAUSAL FACTORS
Personal Factor:
Age, weight, degree of fitness, degree ofacclimatization, metabolism, use of drug or alcohol,type of clothing worn, hypertension
Environmental Factor:
Radiant heat, air movement, conduction, relativehumidity
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EFFECTS ON PERSONNEL
The severity at which a person will burn is basedmainly on the depth to which the burn penetrates,which is dependent on:
Intensity of thermal energy transfer through-
* Radiation
* Convection
* ConductionAbsorptivity of the skin
Length of exposure
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Conduction
Convection
Radiation
HEAT TRANSFER MECHANISM
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HEAT DISORDER AND HEALTHEFFECTS
A. Heat Cramps
Involve muscular pains and spasms, coldsweating and vomiting. Generally occurs due to adepletion of salt and potassium.
Action: Replenish the bodys salt and potassiumsupply orally. (ie. Commercially produce liquids
with proper quantity of salts, potassium,electrolytes and other elements).
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B. Heat Exhaustion
Next step after heat cramp. May lose the ability tostand erect. Water or salt depletion. Body
becomes dehydrated.
Action: Move person to a cool, but not coldenvironment and allowed to rest lying down.Fluids should be taken slowly but steadily bymouth until the urine volume indicates that the
bodys fluid level is once again in balance.
HEAT DISORDER AND HEALTHEFFECTS
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C. Heat Stroke
More serious than heat cramps or exhaustion.Patient will have a temperature of 105 F(40.5 C)or more, with corresponding hot skin, but it will
be dry, with no perspiration.
Action: Immediately reduce his or her body coretemperature. Victim should be immersed inchilled water if facilities are available.
HEAT DISORDER AND HEALTHEFFECTS
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CONTROLLING AND PREVENTINGHEAT STRESS
Engineering controls: ventilation, shielding, cooling fans etc .
Work practise : provide plenty of drinking water, firstaids training
Alternating work and rest periodsEmployee education
Heat Stress Card : OSHA publication 3154
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CLASSIFICATION OF BURNSEVERITIES
Tolerance to Burns:
The ability of a person to survive exposure to heat isgoverned by two factors:
Tolerance to pain
Heat-exposure level at which second-degree burns begin
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SEVERITY OF BURNSFirst-degree burn: Only cause a redness of the skin,which indicates a mild inflammation. The mostcommon is sunburn. All are considered minor.
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Part II:
Pressure Hazards
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Pressure Hazard - Hazard caused by adangerous condition involving pressure
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BOILER AND PRESSURE VESSELS HAZARDS
Boiler: A closed vessel in which water isheated to form steam, hot water, or hightemperature water under pressure.
Common types of failures:
Cracking
Leakage
Explosion
Rupture
Corrosion
Creeping
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BOILER AND PRESSURE VESSELS HAZARDS
Common Hazards associated with rupture / leakage:
Blast effects
Fragmentation
Suffocation
Poisoning
Fire
Chemical burn
Thermal burn
Explosion
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BOILER AND PRESSURE VESSELS HAZARDS
Potential causes of hazards :
Design, construction, and / or installation errors
Poor or insufficient training of operators
Human Error
Mechanical breakdown / failure
Failure or blockage of control and / or safety devices
Insufficient or improper inspectionImproper applications of equipment
Insufficient preventive maintenance
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Proper design
Proper training
Proper housekeeping
Continual inspection
Visual observation (for detecting cracks)
Use of appropriate safety equipment
Periodic testing
PREVENTIVE MEASURES
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NON DESTRUCTIVE TESTING OF PRESSUREVESSELS
Visual Examination visually check for sign ofcorrosion, erosion or hydrogen blistering
Liquid Penetration Test use liquid penetrantover an area and letting it seep in. When removed,some of penetrant remains in the area ofdiscontinuities
Magnetic Particle Test applying fine particles of ferromagnetic material to surface ofvessel. Discontinuity can cause disturbance inmagnetic field
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Radiography Test Use X-ray negative on a given portion of vessel. Irregularities (eg. Holes, voids) ordiscontinuities appear darker on the X-ray negative
Ultrasonic Testing short signal induced into thematerial. Waves reflected back from discontinuities aredetected by transducers
NON DESTRUCTIVE TESTING OF PRESSUREVESSELS
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Summary Heat and temperature hazards Factors involved in heat hazards Health effects (e.g. Heat stroke etc) Severity of burns (e.g 1 st degree burn etc) Pressure hazards Boilers and pressure vessels
Prevention measures for heat, temperatureand pressure hazards