MODULE 5 - CLASS NOTES - MCN401- INDUSTRIAL SAFETY ENGINEERING

MODULE 5 ((hazard identification and analysis)

Hazard and risk, Types of hazards –Classification of Fire, Types of Fire extinguishers, fire explosion and toxic gas release, Structure of hazard identification and risk assessment. Identification of hazards: Inventory analysis, Fire and explosion hazard rating of process plants - The Dow Fire and Explosion Hazard Index, Preliminary hazard analysis, Hazard and Operability study (HAZOP)) – methodology, criticality analysis, corrective action and follow-up. Control of Chemical Hazards, Hazardous properties of chemicals, Material Safety Data Sheets (MSDS).

Hazard and Risk

Hazard is a source or a situation with potential to cause harm such as human injury or ill- health, damage to property or environment or both. hazard means danger or potential danger. Hazards are identified in the performance of various activities, storage and handling of materials, and operation and maintenance of plants and equipment.

Risk is the chance or probability that a person will be harmed or experience an adverse health effect if exposed to a hazard. It may also apply to situations with property or equipment loss, or harmful effects on the environment.

For example: the risk of developing cancer from smoking cigarettes could be expressed as: "cigarette smokers are 12 times (for example) more likely to die of lung cancer than non-smokers"

Types of hazards

Hazards may be classified as under:

1. Mechanical hazards.

2. Electrical hazards.

3. Chemical hazards.

4. Construction hazards.

5. Physical (Hygiene) Hazards.

6. Biological Hazards.

7. Stress Hazards.

8. Radiation Hazards.

Mechanical Hazards

Mechanical hazards are the most spotted hazards and are responsible for the majority of the accidents in work situation, therefore every work place and every equipment shall be properly examined for identifying mechanical hazards and for taking mitigating measures.

Common source of mechanical hazards are:

(i) Unguarded or inadequately guarded shafting, shaft ends, belt drives, gears, pulleys, projections on rotating parts, chain and sprocket drives, any exposed component parts of machines, power driven equipment which rotate rapidly, or any machine component which moves rapidly, which may strike, crush: or otherwise injure a worker etc.

(ii) Other important mechanical hazards relate to machine of all kinds including transmission machinery, hand tools, handling materials, lifting and other appliances.

(iii) Lifting equipment may be cause of accidents due to mechanical failure or unsafe operating practice. Frequent periodic inspection and maintenance of such parts as chain, wire ropes, gears, clutches, brakes, bearings, etc., may constitute a vital part of efficient performance:

(iv) Improper use of tools. One must always use right type of tools for various types of jobs. They-must be placed properly and should be well maintained.

(v) Failure of components of a mechanical system due to faulty design, faulty assembly, lack of repair and maintenance.

(vi) Laxity in the use of PPE.

(vii) Pressure hazards and pressure vessels.

Electrical hazards

Since almost every machinery and plant is power driven, severe injury may cause by the passage to the body through electric current. These may be due to contact with wire, cable or rail or from stroke of lightening. The immediate effect of this is shock which may be relatively mild or severe so as to cause death depending upon the strength of the current and/or the path it takes passing the earth through the body. Another result is burning and the burns may be severe and deep especially with higher voltage. Causes of the electric hazards maybe of following types:

(i) Electric shocks may be caused by an exposed live conductor or a faulty piece of equipment.

(ii) Electrical flashovers resulting in death, fire, damages etc.

(iii) Electric faults resulting in arcing, explosions and fires.

(iv) Explosions in electric equipment resulting in damage to installations and deaths.

(v) Electrocution due to long boom of a mobile crane or showel coming in contact with overhead power line.

(a) A mobile crane with a long boom can accidentally contact a power line or other overhead live conductor.

(b) A man carrying or climbing an aluminium ladder can come in contact with overhead conductors.

(vii) Other causes may be:

(a) Faulty equipment, either badly installed or improperly repaired/badly maintained.

(b) Unskilled electricians.

(d) Defective wiring which may cause short circuit.

(e) Poor installations. misuse or overloading.

(j) Aging and attack by foreign substances cause insulation failures which causes electrical fires

Chemical hazards

The usages of chemicals with the resultant hazardous gases, vapours and fumes is one of the most dangerous thing in industries. The list of toxic gases vapours and fumes is exhaustive.

(i) Metallic dusts and fumes,

(ii) Mineral dusts.

(iii) Volatile liquids and solids,

(iv) Poisonous gases,

(v) Toxic chemicals,

(vi) Spontaneous fire due to various types of gases

Construction hazards

Various construction activities are big source of safety and health hazards. Some of the common hazards, not discussed above are:

(i) Formwork, scaffolding, ladder and platform.

(ii) Foundation and excavation work.

(iii) Work on or adjacent to water.

(iv) Cement concrete work.

(v) Asphalt concrete work.

(vi) Demolition.

(vii) Tunnelling and underground work.

(viii) Handling, storage and transportation of explosives.

(ix) Drilling and blasting.

(x) Piling work.

(xi) Work in sewers.

(xii) Shaft excavation works.

Physical (Hygiene) Hazards

Hygiene in construction industries identifies and evaluates hazards present in the workplace which may cause sickness. impaired health and wellbeing. discomfort and inefficiency among workers, and devising means to control or eliminate them. Various hygiene or physical hazards are:

(i) Temperature, noise, vibration, heat, cold. humidity, dampness.

(ii) Ergonomic hazards. Such as improper tools, lifting, repeated motions in awkward position, incorrect chairs. wrong postures, incorrect or poor job design.

(iii) Improper lighting/illumination.

(iv) Ultraviolet and infra-red rays, ionizing, radiations.

Biological Hazards

Biological hazards include bacteria, viruses, insects, fungi, sanitation, sewage, hazardous waste. These dangers can come from unclear rest room, fungus, insect sting, animal bites, poorly stored medical waste.

Stress Hazards

Stress can lead to long term health problems like headaches, anxiety and impatience, which are early signs of stress.

Causes of stress include:

· Heavy workloads.

· Working in shifts

· Fear of job loss

· Lack of control over the peace of work

· Noise and vibrations

· Conflict with the employer

Radiation Hazards

Radiation dose is defined as the total quantity of radiation energy absorbed by part or all the body. Radiation protection programmes are important like detection and measurement, shielding and monitoring. The uncontrolled entry of radioactivity into the body to produce harmful effects.

CLASSIFICATION OF FIRE, TYPES OF FIRE EXTINGUISHERS

There are five classes of fires:

Class A: solid materials such as wood or paper, fabric, and some plastics

Class B: liquids or gas such as alcohol, ether, gasoline, or grease

Class C: electrical failure from appliances, electronic equipment, and wiring

Class D: Certain flammable metallic substances such as sodium, titanium, zirconium, or magnesium

Class K: grease or oil fires specifically from cooking

Class A Fires: “Ordinary” Fires

Class A fires are the most common of the 5 different classes of fires. They occur when common combustible materials like wood, paper, fabric, trash, and light plastics catch fire. it’s recommended to have adequate protection against “ordinary” fires in addition to other condition-specific fires.

Despite being “ordinary”, don’t rule this class of fire as low-risk. If there’s an abundance of fuel present, these fires can intensify quickly. It’s best to put out a Class A fire quickly before it spreads using water or monoammonium phosphate.

Class B Fires: Liquids & Gases

Class B fires involve flammable liquids and gases, especially fuels like petroleum or petroleum-based products such as gasoline, paint, and kerosene. Other gases that are highly flammable are propane and butane, which are common causes of Class B fires. The best way to deal with these types of fires is by smothering them or removing oxygen using foam or CO2 fire suppression equipment.

Be aware that Class B fires do not include grease fires or cooking fires, which belong to their own class, Class K.

Class C Fires: Electrical Fires

Electrical fires fall under Class C and are common in facilities that make heavy use of electrical equipment, but they can occur in a wide range of industries. For example, data centres might be an obvious risk area for Class C fires. They must have safeguards in place to deal with electrical fires.

Construction sites are another common Class C fire risk: electrical power tools or appliances used for cooking can cause sparks to ignite combustible materials and intensify rapidly. Old buildings with bad wiring or space heaters present more concerns.

Electrical fires require non-conductive materials to extinguish the flame, so water alone is not a good solution. Facilities with sensitive equipment may prefer clean agent suppression because it won’t leave residue or damage electrical equipment.

Class D Fires: Metallic Fires

Class D fires are not as common as the other classes, but they do require special attention because they can be especially difficult to extinguish. Metallic fires involve flammable materials like titanium, aluminum, magnesium, and potassium — all commonly occurring in laboratories.

Class D fires cannot be addressed with water, as this can exacerbate the fire and be potentially dangerous. Dry powder agents are the best solution for smothering the flames and limiting damage to property or people.

Class K Fires: Grease Fires or Cooking Fires

Class K fires involve flammable liquids, similar to Class B fires, but are specifically related to food service and the restaurant industry. These common fires start from the combustion of liquid cooking materials including grease, oils, and vegetable and animal fats. Because they can spread quickly and be difficult to manage, Class K fires are some of the most dangerous. Water can make the situation worse, but smothering the flames or using a wet agent fire extinguisher is effective.

Using the right extinguisher is essential to put out the fire safely.

Water

Water is the primary liquid used in these extinguishers, although sometimes other additives included. pure water fire extinguishers are not suitable for use in freezing conditions. Hence Certain types of water fire extinguishers contain antifreeze which will allow the extinguisher to be used in freezing conditions. Water type fire extinguishers contain wetting agents which are designed to help increase its effectiveness against fire. These extinguishers are intended primarily for use on A fires.

Water mist extinguishers are a type of water fire extinguisher that uses distilled water and discharges it as a fine spray. Water mist extinguishers are used in operating rooms, museums etc.

Film-forming foam type

AFFF (aqueous film-forming foam) and FFFP (film-forming fluoro protein) fire extinguishers are rated for use on both Class A and Class B fires. As the name implies, they discharge a foam material rather than a liquid or powder. they are not suitable for use in freezing temperature. An advantage of this type of extinguisher is the ability of the agent to float on and secure the liquid surface, which helps to prevent reignition.

Carbon Dioxide type

The principal advantage of Carbon Dioxide (C02) fire extinguishers is that the agent does not leave a residue after use. This can be a significant factor where protection is needed for delicate and costly electronic equipment, Other typical applications are food preparation areas, laboratories, and printing or duplicating areas. Carbon dioxide extinguishers ate listed for use on Class B and Class C fires. Because the agent is discharged in the form of a gas/ snow cloud, it has a relatively short range of 3 ft to 8 ft. This type of fire extinguisher is not recommended for outdoor use where windy conditions prevail or for indoor use in locations that are subject to strong air currents, because the agent can rapidly dissipate and prevent extinguishment. The concentration reduces the amount of oxygen in the vicinity of the fire and should be used with caution when discharged in confined spaces.

Halogenated agent types

a. Halon

The Halon fire extinguisher has an agent that is similar to carbon dioxide & is suitable for cold weather installation and leaves no residue. It is important to note that the production of Halon has been phased out because of the environmental damage it causes to the earth's ozone.

b. Halon Alternative Clean Agents

There are several clean agents that are similar to halon agents in that they are nonconductive, noncorrosive, and evaporate after use, leaving no residue. Larger models of these fire extinguishers are listed for Class A as well as Class and Class C fires, which makes them quite suitable for use on fires in electronic equipment. When discharged, these agents are in the combined form of a gas/mist or a liquid, which rapidly evaporates after discharge with about twice the range of carbon dioxide.

Dry chemical types

a. Ordinary Dry Chemical

The fire extinguishing agent used in these devices is a powder composed of very small particulates. Types of agents available include sodium bicarbonate base and potassium bicarbonate base.

b. Multipurpose Dry Chemical

Fire extinguishers of this type contain an ammonium phosphate base agent. Multipurpose agents are used in exactly the same manner as ordinary dry chemical agents on Class B fires.

c. Wet chemical

The extinguishing agent can be comprised of, but is not limited to, solutions of water and potassium acetate, potassium carbonate, potassium citrate, or a combination of these chemicals (which are conductors of electricity). On Class A fires, the agent works as a coolant. On Class K fires (cooking oil fires), the agent forms a foam blanket to prevent reignition,

Dry powder types

There are just two types of dry powder fire extinguishers available: standard and specialist. Standard dry powder extinguishers can extinguish almost any type of fire. Specialist dry powder extinguishers are for certain types of metal fires. However, because of the dispersal of powder, it’s important not to use them in enclosed spaces.

FIRE EXPLOSION AND TOXIC GAS RELEASE

Explosion: - It is bursting accompanied by loud noise and destruction and released solid/liquid/gaseous products. Explosion is caused by sudden release of energy and rise of internal pressure in the equipment or at the location. Explosions are characterised by a shock wave which can be hard as a bang and can cause damage to buildings. Explosion is a rapid increase in volume and release of mechanical, chemical or nuclear energy in a sudden and often violent manner with the generation of high temperature and usually with the release of gases. It is a violent bursting as a result of internal pressure and produces loud and sharp sound.

The most common explosion is chemical explosion, usually involving a rapid and violent oxidation reaction that produces large amount of hot gases.

Toxic Gas Releases

Toxic gas releases may cause the plant inoperable and it injures operators. The distance between the planet building and the occupied buildings should be governed by the need to reduce the dangers of explosion, fire and toxicity. Care should be taken that, evacuation routes should not be blocked by poor plant layout, and personnel should usually be housed in building sited in a non-hazard area near the entrance.

Plant layout design techniques applicable for the reduction of the risks from release of flammable or toxic materials include:

(i) Location high volume storage of flammable/toxic materials well outside process areas.

(ii) Locating hazardous plant away from main roadways through the site.

(iii) Provision of terrain to contain and control releases and limit the safety and environment effects.

(iv) Siting of plants in the open air to ensure rapid dispersions of minor releases of flammable gases and vapours and thus prevent concentration and building up, which may lead to flash and explosions.

(v) To avoid aggregation and trapping of flammable/toxic vapours which could lead to a hazardous event, buildings should be designed so that all parts of the buildings are well ventilated by natural or forced ventilation. Maintenance procedures should include the displacement of vapours from hazardous area before work begins.

STRUCTURE OF HAZARD IDENTIFICATION AND RISK ASSESSMENT

Hazard identification is the process of identifying and managing situations where employees and visitors exposed to injury or harm. Risk situations are recognized, evaluated and appraised at an early stage. Risk (or hazard) identification should address both internal or external risks. Internal risks are things that the organisation team can control or influence, while external risks are things beyond the control or influence of the organisation team.

Risk identification is not a onetime event. it should be performed on a regular basis. hazards/risks should be identified for all:

· New activities.

· Existing activities where the rate of occurrence of undesired events is abnormally high.

· Existing activities with exposures. and

· Infrequent/irregular activities.

Tools used in the identification of hazards include:

· Consultation.

· Inspection. A physical inspection of the work environment.

· Illness and injury records. Records of past incidents involving injury and illness highlight sources of potential information

· Specialist advice/information. The identification of some hazards will require specialist advice, research and information.

· Task Analysis. By breaking a task down into its individual elements, hazard associated with the task can be identified.

The steps involved in the hazard identification and risk assessment is listed below.

1. Identify the hazards

The first step to creating your risk assessment is determining what hazards your employees and your business face, including

· Natural disasters (flooding, tornadoes, hurricanes, earthquakes, fire, etc.)

· Biological hazards (pandemic diseases, foodborne illnesses, etc.)

· Workplace accidents (slips and trips, transportation accidents, structural failure, mechanical breakdowns, etc.)

· Intentional acts (labor strikes, demonstrations, bomb threats, robbery, arson, etc.)

· Technological hazards (lost Internet connection, power outage, etc.)

· Chemical hazards (asbestos, cleaning fluids, etc.)

· Mental hazards (excess workload, bullying, etc.)

Take a look around your workplace and see what processes or activities could potentially harm your organization. Include all aspects of work, including remote workers and non-routine activities such as repair and maintenance. You should also look at accident/incident reports to determine what hazards have impacted your company in the past.

2. Determine who might be harmed and how

As you look around your organization, think about how your employees could be harmed by business activities or external factors. For every hazard that you identify in step one, think about who will be harmed should the hazard take place.

3. Evaluate the risks and take precautions

Now that you have gathered a list of potential hazards, you need to consider how likely it is that the hazard will occur and how severe the consequences will be if that hazard occurs. This evaluation will help you determine where you should reduce the level of risk and which hazards you should prioritize first.

4. Record your findings

If you have more than five employees in your office, you are required by law to write down your risk assessment process. Your plan should include the hazards you’ve found, the people they affect, and how you plan to mitigate them. The record—or the risk assessment plan—should show that you:

· Conducted a proper check of your workspace

· Determined who would be affected

· Controlled and dealt with obvious hazards

· Initiated precautions to keep risks low

· Kept your staff involved in the process

5. Review your assessment and update if necessary

Your workplace is always changing, so the risks to your organization change as well. As new equipment, processes, and people are introduced, each brings the risk of a new hazard. Continually review and update your risk assessment process to stay on top of these new hazards.

INVENTORY ANALYSIS

FIRE AND EXPLOSION HAZARD RATING OF PROCESS PLANTS - THE DOW FIRE AND EXPLOSION HAZARD INDEX

The hazard classification guide developed by the Dow Chemical Company and published by the American Institute of Chemical Engineering, gives a method of evaluating the potential risk from a process and assessing the potential loss. A numerical “Fire and explosion index” (F&EI) is calculated, based on the nature of the process and the properties of the process materials. The larger value of the F&EI, the more hazardous the process.

It is worthwhile estimating F & EI index at an early stage in the process design, as it will indicate whether alternative, less hazardous process routes should be considered or not. Judgement based on experience with similar process is needed to decide the magnitude of the various factors used in the calculation of the index

Calculation of the Dow F & EI

The first step is to identify the units that would have the greatest impact on the magnitude of any fire or explosion. The index is calculated for each of these units.

The basis of the F & EI is a Material Factor (MF). The material factor is a measure of the intrinsic rate of energy release from the burning explosion or other chemical reaction of the material.

The MF is then multiplied by a Unit Hazard Factor, F3 to determine the F & EI for the process unit. The Unit Hazard factor is the product of two factors which take account of the hazards inherent in the operation of the particular process unit the general and special process hazards.

The special process hazards are factors that are known from experience to contribute to the probability of an incident involving loss.

Examples: -

· Toxic materials: the presence of toxic substances after an incident will make the task of the emergency personnel more difficult.

· Operation in or near flammable range: cover for the possibility of air mixing with material in equipment or storage tanks, under conditions where the mixture will be within the explosive range.

· Dust explosion: covers for the possibility of a dust explosion.

· Relief pressure: Equipment design and operation becomes more critical as the operating pressure is increased.

· Quantity of flammable material: the potential loss will be greater the quantity of hazardous material in the process or in storage.

· Corrosion and erosion: despite good design and materials selection, some corrosion problems may arise, both internally and externally.

· Leakage-joints and packing: this factor accounts for the possibility of leakage from gaskets. Pump and other shaft seals and packed glands.

· Use of fired heaters: the presence of boilers or furnaces, heated by the combustion of fuels, increases the probability of ignition should a leak of flammable material occur from a process unit.

· Hot oil heat exchange system: most special heat exchange fluids are flammable and are often used above their flash points; so their use in a unit increases the risk of fire or explosion.

· Rotating equipment: this factor accounts for the hazard arising from the use of large pieces of rotating equipment: compressors, centrifuges, and some mixers.

The basic safety and fire protective measures that should be included in all chemical process design are listed below. This list is bases on that given in the Dow Guide, with some minor amendments.

· Adequate, and secure, water supplies for firefighting.

· Correct structural design of vessels, piping, steel work.

· Pressure-relief devices.

· Corrosion-resistant materials and adequate corrosion allowances.

· Segregation of reactive materials.

· Earthing of electrical equipment.

· Safe location of auxiliary electrical equipment, transformers, switches gear.

· Provision of back-up utility supplies and services.

· Compliance with national codes and standards.

· Provision for access of emergency vehicles and the evacuation of personnel.

· Adequate drainage for spills and fire-fighting water.

· Insulation of hot surfaces.

· No glass equipment used for flammable or hazardous materials,

· Adequate separation of hazardous equipment.

· Protection of pipe racks and cable trays from fire.

· Provision of block valves on lines to main processing areas.

· Protection of fired equipment (heaters, furnaces) against accidental explosion and fire.

· Safe design and location of control rooms.

PRELIMINARY HAZARD ANALYSIS

Preliminary hazard analysis (PHA) is a semi-quantitative analysis performed with the intention of identifying all potential hazards and accidental events that can cause an industrial accident. This type of analysis ranks the identified accidental events according to their severity and proposes hazard controls and follow-up actions

PHA should be carried out in the early stages of a project and continue throughout the system or product's life cycle. The preliminary hazard analysis focuses on identifying immediate hazards, assessing the severity of potential accidents that could occur because of these hazards, and identifying safeguards for reducing the risks associated with the hazards. By identifying weaknesses early in the life of a system, PHA aims to save time and money.

PHA Main Steps

1. PHA prerequisites

2. Hazard identification

3. Consequence and frequency estimation

4. Risk ranking and follow-up actions

1. PHA prerequisites

· Establish PHA team

· Define and describe the system to be analysed

§ System boundaries (which parts should be included and which should not)

§ System description; including layout drawings, block diagrams, and so on

§ Use and storage of energy and hazardous materials in the system

§ Operational and environmental conditions to be considered

· Collect risk information from previous and similar systems

(e.g., from accident data bases)

2. Hazard identification

All hazards and possible accidental events must be identified. It is important to consider all parts of the system, operational modes, maintenance operations, safety systems, and so on. All findings shall be recorded.

3. Consequence and frequency estimation

The risk related to an accidental event is a function of the frequency of the event and the severity of its potential consequences. To determine the risk, we have to estimate the frequency and the severity of each accidental event.

4. Risk ranking and follow-up actions

The risk is established as a combination of a given event/consequence and a severity of the same event/consequence. This will enable a ranking of the events/consequences in a risk matrix as illustrated below:

Advantages of PHA:

1. Helps in ensuring safety of the system

2. Hazards are detected at the early stage of project development

3. Provides basis for design decisions

4. Design time decreased by reducing number of inappropriate events

5. Modifications are easier and less expensive to implement at the initial stages of the design

HAZARD AND OPERABILITY STUDY (HAZOP)

One common method for PHAs is a Hazard and Operability study, better known as a HAZOP.

A HAZOP is a systematic assessment tool used to identify and address potential hazards in industrial processes before an incident occurs that could affect the Safety of people or assets while hindering Productivity. HAZOP studies are typically performed while new facilities are being designed and constructed, when new processes are added or when processes change. In this approach, the process is broken down into steps, and every variation in work parameters is considered for each step, to see what could go wrong. HAZOP is commonly used with chemical production and piping systems.

A Hazard and Operability Study systematically investigates each element in a process. The goal is to find potential situations that would cause that element to pose a hazard. There are four basic steps to the process:

1. Forming a HAZOP team

2. Identifying the elements of the system

3. Considering possible variations in operating parameters

4. Identifying any hazards or failure points

1. Form a HAZOP Team

To perform a HAZOP, a team of workers is formed, including people with a variety of expertise such as operations, maintenance, instrumentation, engineering/process design, and other specialists as needed. These should not be “newbies,” but people with experience, knowledge, and an understanding of their part of the system. The key requirements are an understanding of the system, and a willingness to consider all reasonable variations at each point in the system.

2. Identify Each Element and its Parameters

The HAZOP team will then create a plan for the complete work process, identifying the individual steps or elements. This typically involves using the piping and instrument diagrams (P&ID), or a plant model, as a guide for examining every section and component of a process. For each element, the team will identify the planned operating parameters of the system at that point: flow rate, pressure, temperature, vibration, and so on.

3. Consider the Effects of Variation

For each parameter, the team considers the effects of deviation from normal. For example, “What would happen if the pressure at this valve was too high? What if the pressure was unexpectedly low? Would the rate of change in pressure (delta-p) pose its own problems here?” Don’t forget to consider the ways that each element interacts with others over time; for example, “What would happen if the valve was opened too early, or too late?”

4. Identify Hazards and Failure Points

Where the result of a variation would be a danger to workers or to the production process, you’ve found a potential problem. Document this concern, and estimate the impact of a failure at that point. Then, determine the likelihood of that failure; is there a real cause for the harmful variation? Evaluate the existing safeguards and protection systems, and evaluate their ability to handle the deviations that you’ve considered.

After that, the team will outline specific recommendations to reduce the likelihood of the deviation or reduce associated risks and assign responsibility for carrying out those recommendations. The team will repeat this process until all possible deviations have been exhausted before moving onto the next node.

CRITICALITY ANALYSIS

Criticality analysis is defined as the process of assigning assets a criticality rating based on their potential risk of failure. Criticality analysis lets you understand the asset's potential risks that could impact your operation.

§ A criticality score can be employed as an input to help determine the final priority ranking for maintenance tasks.

§ It can help identify high-level risk reduction strategies for specific equipment

§ It can assist with figuring out the optimum number of spare parts for each piece of equipment.

§ It can provide valuable input for budgeting discussions, so high-criticality equipment is given higher priority for upgrades or replacement.

§ Criticality analysis helps reliability engineers focus their efforts and energy on the most critical assets.

Steps

1. Compile a list of assets to cut that won't exceed 20 percent of all assets. Best practice for this is a 5-to-1 or greater ratio.

2. Put together a team of personnel from the operations, maintenance, engineering and procurement side of the organization to conduct a survey of the plant equipment. Equipment operators should be included in this team as well.

3. Next, rank the criticality of the assets using an established formula.

Equipment Criticality = Failure Frequency (per year) x Cost Consequence ($) = Risk ($ per year).

The cost consequence in this formula is the cost of lost production plus the repair costs.

4. Once you have your criticality ratings, a criticality analysis can help you choose a proper risk mitigation strategy that you can apply to each asset. For example:

CONTROL OF CHEMICAL HAZARDS

The chemicals may be broadly classified as:

1. Irritants. Ammonia, sulphur dioxide, chlorine, hydrogen sulphide etc.

2. Asphyxiants. Carbon monoxide, carbon dioxides, nitrogen, hydrogen

3. Anaesthetics. Gasolene, ether, alcohol, benzene, naphthalene. etc.

Chemicals can cause suffocation, irritation to respiratory tract or other vital organs like lever, kidney etc. Some chemicals cause semi/unconsciousness. Slow chemical exposure over long periods causes chronic health problems, e.g. Caners.

Toxics can enter into human tissues:

§ through skin absorption.

§ by inhalation through respiratory system.

§ by swallowing, and

§ by eyes.

The effects of toxic substance on the workmen depend upon.

§ Rate of absorption of toxic substances in the human body.

§ Concentration and the time of exposure,

§ Personal tolerance level,

§ Susceptibility to toxic substances,

§ Personal hygiene and behaviour

HAZARDOUS PROPERTIES OF CHEMICALS

Chemical substances that have the ability to create a physical or health hazard are considered to be hazardous. Exposure to these substances by different routes including inhalation, dermal absorption, or ingestion can lead to adverse health effects

Toxic

A toxic substance is a substance that can be poisonous or cause health effects. Chemicals can be toxic because they can harm us when they enter or contact the body. Exposure to a toxic substance such as gasoline can affect your health, cause burns, vomiting, and, in very large amounts, drowsiness or death. Some chemicals are hazardous because of their physical properties: they can explode, burn or react easily with other chemicals.

Explosive

Explosive, any substance or device that can be made to produce a volume of rapidly expanding gas in an extremely brief period. Basically chemical explosives are of two types:

(1) detonating or high explosives and (2) deflagrating or low explosives,

Detonating explosives, such as ITNT and dynamite, are characterized by extremely rapid decomposition and development of high pressure, whereas deflagrating explosives such as black and smokeless powders, involve merely fast burning and produce relatively low pressures.

Flammable

Flammability is the ability of a chemical to burn or ignite, causing fire or combustion. Normally a liquid with a flash point under 100°F is considered flammable. This includes

· Gasoline

· Acetone

· alcohols.

Self-reactive

Self-reactive chemicals are thermally unstable liquid or solid chemicals that can undergo exothermic decomposition without interacting with oxygen.

Self-reactive chemicals can start decomposing due to:

· Heat

· Contact with acids

· Contact with heavy metal compounds

· Contact with bases

· Friction

· Impact

Oxidizing

oxidizing chemicals are materials that spontaneously evolve oxygen at room temperature or with slight heating or promote combustion. strong oxidizers are capable of forming explosive mixtures when mixed with combustible, organic or easily oxidized materials. This includes

· Peroxides

· Chlorates

· Perchlorates

· Nitrates

· Permanganates

Corrosive

Corrosive chemicals are defined as chemicals that can cause damage to body tissues. These Chemicals can be dangerous if they come into contact with user’s skins, eyes, and body. It can irritate eyes, burn skins, burn nose and throat if inhaled and may create serious injuries to body. This includes acids and bases such as

· hydrochloric acid, sulphuric acid, and hydrofluoric acid

· ammonium hydroxide, potassium hydroxide, and sodium hydroxide

MATERIAL SAFETY DATA SHEETS (MSDS).

A Material Safety Data Sheet (MSDS) is a document that contains information on the potential hazards (health, fire, reactivity and environmental) and how to work safely with the chemical product. It is an essential starting point for the development of a complete health and safety program. It also contains information on the use, storage, handling and emergency procedures all related to the hazards of the material. The MSDS contains much more information about the material than the label. MSDSs are prepared by the supplier or manufacturer of the material. It is intended to tell what the hazards of the product are, how to use the product safely, what to expect if the recommendations are not followed, what to do if accidents occur, how to recognize symptoms of overexposure, and what to do if such incidents occur.

Nine (9) categories of information that must be present on an MSDS

1. Product Information: product identifier (name), manufacturer and supplier’s names, addresses, and emergency phone numbers

2. Hazardous Ingredients

This section will include: The chemical names and concentrations concerning the hazardous ingredients

3. Physical Data

This section includes information indicating how it looks and how it will behave when it is used, stored, spilled and how it will react with other products indicated through:

· The state it is in e.g. liquid

· The odour and appearance of the product

· The specific gravity, vapour density, evaporation rate, boiling point and the freezing point

· The vapour pressure, the higher the concentration the higher the possible air concentration

· The odour threshold, which is the lowest airborne concentration of a chemical that can be perceived by smell

· The pH reflecting the corrosive or irritant nature of the product

4. Fire or Explosion Hazard Data

This section describes:

· The temperature and conditions that can cause the chemical to catch fire or Explode

· Means of extinction including the type of fire extinguisher required

· Personal Protective Equipment required for fire fighting

· Some of the storage requirements

5. Reactivity Data: information on the chemical instability of a product and the substances it may react with.

This section describes:

· The chemical stability of the product and its reactions to light, heat, moisture,

· shock and incompatible materials

· Storage requirements based on the reactivity or instability of the product

· Incompatible products that must not be mixed or stored near each other

· The need for disposal before they become extremely reactive

6. Toxicological Properties: health effects

This section describes:

· The harmful effects of exposure

· How the product is likely to enter the body and what effects it has on the organs in the body

· The short-term (acute) and long-term (chronic) health effects from exposure to the product

· The exposure limits, which indicates the maximum concentration in air of a hazardous substance (gas, vapour, dust, mist, fume) to which nearly all workers (without personal protective equipment) can be repeatedly exposed without adverse health effects.

· If these limits are to be exceeded, the worker must use recommended personal protective equipment. Exposure limits are expressed as ppm for gases and vapours and as mg/m3 for dusts, fumes and mists

7. Preventive Measures

· Instruction for the safe use, handling and storage of the product

· The personal protective equipment or safety devices required

· The steps for cleaning up spills

· Information on the waste disposal requirements

8. First Aid Measures

· Specific first aid measures related to acute effects of exposure to the product

· First aid steps in the correct sequence

· Information to assist in planning for emergencies

9. Preparation Information: who is responsible for preparation and date of preparation of MSDS

This section includes:

· The name address and telephone number of who prepared the MSDS

· The date the MSDS was prepared

KTU MODEL QUESTIONS

1. Differentiate Hazard and Risk. (3 marks)

2. Why MSDS is mandatory for chemical products. (3 marks)

3. What is Hazard and Operability Analysis? How do you conduct a HAZOP analysis? (14 Marks)

4. Discuss about different types of chemical hazards. (14 marks)

Dear Faculty & Students ,

Please send your valuable suggestions,corrections, or inaccuracies to manojkumar@scmsgroup.org

Corrections will be done with proper acknowledgement.

Thank you

Dr Manoj Kumar B