Safety , Accident , Hazards and Risk , Engineering drawing and safety , UPSC ESE , Mechanical engineering

 Introduction

• It is the condition of being free from accidents , hazards , risk , and related unexpected events.
• Safety is everyone responsibility 

1. Employee : wearing PPE, adhering to safety norms
2. Employer : by providing safety guidelines , proper training , regular inspection , etc
3. Government : by framing safety policies , performing safety audits, etc

Note : 

1. If anyone observes any unsafe act , then he she must report immediately to avoid any accident injury.
2. Safety policy is a written document that is given by a employer to employee or public committing to provide health and safety, it must contain minimum rules and regulation but providing maximum safety.

3 E's of safety:

1. Education : creating awareness regarding awareness of safety 
2. Enforcement : enforcing the safety rules on workers
3. Engineering : redesign of tools , equipments and jobs for safety of workers.

Need of safety:

• To control occupational health problems like chronic respiratory diseases , musculo skeletal disorder, hearing problem , skin problem
• We need to redesign the working station , equipment and working environment to provide safety 
• Control human factors responsible for accidents eg peer pressure , emotions , anxiety ,etc.
• Health and safety law in India is given for only four industries: 

1. Factories 
2. Mining 
3. Docks/ports
4. Construction

Accident , hazard and risks

1. Accident : it is unexpected or undesired event that causes injuries to person or loss of property.

• Factors that trigger accident is given by accident causation theory:

a) The domino theory: HW Heinrich statistics :

• 88% accident : unsafe act of worker like negligence , ignorance , etc
• 10% accident : unsafe condition at workplace like improper work station , lighting ,etc
• 2% accident : natural disaster like earthquake , flood

1. Ancestry and social environment : people inherit from their ancestors and learn from social environment  negative traits like sturbbornes , wreckless ness , etc
2. Fault of person : these negative traits proves to develop fault in person.
3. Unsafe act : the fault of person triggers to do some unsafe act 
4. Accident : result of unsafe act 
5. Injury : end result of accident

2. Human factors model (accident caused by human error)

• Overload : imbalance between the workload and capacity of worker.
• Inappropiate response : not proper response to the situation at hand
• Inappropriate activities : activities performed while doing work is in appropriate

3. Peterson accident / incident theory (extension of ferrell's theory )

• Ergonomic means job that fit worker that does not stress the worker. eg adjustable seats
• If there is imbalance between job and worker capacity then it will result to accident and injury.

Factors:

1. Incompatible work station i.e. work station not designed properly for safe working . eg no adjustable light, ventilation
2. Two or more social position hold by same person

Decision to error

• Logical decision based on the situation: eg removing PPE for fast work

System failure :

It is related to management.

4. The epidemiological theory:

Background:

Susceptibility: in presence of certain situation , the behavioural that occurs in the work instantly.

Defition: 

1. It is the study of casual relation between environment and accident or disease .
2. It is unintentional , unavoidable and unexpected event arising due to interacion between host , agent and environment leading to risk taking and perception of danger.

5. System theory:

Features to be considered in :

• Job requirement 
• Worker's ability and limitation
• What if gained if the task is successfully accomplished
• What is lost if the task is attempted but failed.
• What is lost if the task is not attempted

Hazard:

• It is anything that has potential to cause harm. eg entrapment under soil , slip , fall , etc

Classification of hazard:

Hazard identification technique:

1. Preliminary hazard analysis:

It is a semi quantitative analysis performed to 

• Identify the potential hazard and accidental event that cause accident.
• Rank the accidental event according to its severity
• Identify the required control hazard and follow the action.

2. FMEA (failure mode effect analysis)

• Failure mode : mode or ways in which something fails
• Effect analysis : study of consequences of failure
• It is study of failure mode and its effect and also to control these effect of failures or failures itself.
• It is an inductive process and it is bottom to top approach i.e. it start at root level and implemented till product life cycle.
• Eg atm machine

3. Hazop : hazard and operability study

• It is used in process industries like petroleum , natural gas , etc which operates continuosly
• A systematic examination of hazard , failure and operability is done .
• Hazop process:

1. Form a hazop team consist of experts from various fields . no newbabies are allowed 
2. Identity each element and parameter i.e. how elements work and what are potential cause if fails
3. Consider variation of parameter i.e. deviation from normal values 
4. Identify hazard and failure points

4. Job hazard analysis (JHA)

It studies the relationship between the workers , his task , tools and environment in which he is working

Step:

a) Select the job according to the severity of accident or injury

b) List the step worker takes to perform the task

c) Identify the hazard at each step

d) Determine preventive measure

5. Fault tree analysis (FTA)

• It is top to bottom approach
• It uses boolean logic like,
• And gate : output is obtained only where there exist both points
• Or gate : output is obtained even if there is one input

FTA supplements FMEA but reverse is not true

Eg fire:

6. Human error analysis:

• It prevents error due to human before it occurs
• Two step process

1. Observe the weaker and note all possible hazard
2. Actually perform the task to get first hand experience of hazard

Hierarchy of hazard control:

Risk: probablity that a person is harmed when exposed to hazard

Risk spectrum:

ALARA = as low as reasonably achieve

ALARP = as low as reasonably practiceable

eg corona case, radiation from radioactive material

In matrix form :

Risk management process

1. Identify the risk
2. Assess the risk
3. Control the risk
4. Review control