lecture 8-cdb 2012-may 2014

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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.


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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.


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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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Common Hazards associated with rupture / leakage:

Blast effects

Fragmentation

Suffocation

Poisoning

Fire

Chemical burn

Thermal burn

Explosion

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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

lecture 8-cdb 2012-may 2014

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