What Is Work Permit? Different Types Of Work Permit, Hazards and their Precaution- Interview QnA by Job Availables

In this Blog we will discuss What is Permit?, Different types of work permit, hazard associated with this work and Precautions to be taken before starting any type of job.

What Is Work Permit ?

A Work Permit is a formal written safety documents that is implemented to help prevent accident or injury to personnel, prevent damage to plant/ machinery.

Work Permit is required for operational or maintenance job activity.

Work permit system provides systematic method of risk assessment, hazards Identification, and precautions to be taken during carrying job or before job. 

The work permit is issued by Operation persons( Issuer) such as Shift In-Charge, Engineer, or other competent person and Acceptor ( Executor) is the person who carries out the work. Usually acceptor is service department like Maintenance, Electrical, Instrumentation etc. Before preparing work permit, Issuer and acceptor make risk assessment i.e hazard identification, precautions taken before starting work and during work. After Risk Assessment, work permit is classified on the basis of hazard involving in the work, type of work etc.

Work permit is approved by all concerned departments with necessary documents such as Job Safety Analysis or Hazard identification and task risk assessment.

How Many Types of Work Permit?

1. Cold Work Permit:

2. Hot Work Permit

3. Confined Space/ Vessel Entry Work Permit

4. Excavation Work Permit

5. Height Work Permit

6. Electrical Work Permit

1. Cold Work Permit/ General Work Permit: 

Cold Work is defined as any work which does not produce sufficient heat or Sparks to ignite flammable or combustible material.

For all type of Non routine job etc. general work permit / cold work permit is required

2. Hot Work Permit: 

Hot work is defined as any Work such as welding, cutting, flame cutting which can produce flame, spark or fire hazard

Some Examples of hot work:

Welding or Flame Cutting

Grinding 

Drilling using an electric drill 

Using matches or lighter

Use of any Device which can capable for producing a source of ignition

In Chemical or pharmaceutical Industry many hazardous and flammable substances are handled in large quantities, so there are Chance's of fire or explosion, in the event of a leak or a spillage, if the ignition Sources are not Properly eliminated chances of Fire or explosion, thus it is necessary to take precautions before starting Hot Work

Precautions to be taken Before Starting Hot Work: 

1. Gas testing done before starting the 

hot work. LEL Should be zero also Continuously monitor for O2 and LELs during hot work.

2. The equipment to be worked on shall be positively isolated both mechanically and electrically. Mechanical isolation shall be achieved either by disconnection or by blinding 

3. The Equipment should be properly decontaminated, free form vapours, gases or any other combustible material

4. The worker should wear suitable type of Personal protective equipment(PPE)

5. Any combustible material such as paper cartons, located near by shall be removed. 

6. Hot work area must be equipped with sufficient fire fighting equipment such as fire extinguisher of the Suitable type, Fire hose shall be in ready condition (connected to the nearby fire Hydrants With nozzles)

7. Use fire blankets, curtains, and shields to protect surrounding areas and workers.

Hazards of Hot Work: 

Fire and Explosion Hazards:

Main hazard of hot work is Fire and Explosion Hazard and also Welding, Cutting Hazards. Exposure of welding arcs and welding fumes can result in serious and disabling long-term health injuries.

3. Confined Space/ Vessel Entry work permit:

Confined Space Work Defined by 3 Conditions: 

1. Where limited entry and Exit

2. Not designed for continuous human occupancy.

3. The Space is large enough for workers to Enter and perform their work

Some Examples of Confined space work:

Boilers, Reactor, Columns, Tank, Chambers, sewers, tunnel, utility vaults, hoppers etc.

Hazard of Confined Space Work: 

1. Oxygen Deficiency or enrichment: 

Oxygen Deficiency: Normal atmosphere contains between 20.8 and 21% oxygen, OSHA defines as oxygen deficient any atmosphere that contains less than 19.5 percent oxygen.

Oxygen Deficiency in an atmosphere can result in asphyxiation.

Low oxygen levels can cause symptoms such as rapid breathing, rapid heart rate, clumsiness, emotional upset, and fatigue.

Very low oxygen percentage can lead to coma, unconsciousness and death can occur.

2. oxygen enrichment: Any atmosphere that contains more than 22% Oxygen is called as Oxygen enriched atmospheres.

Oxygen enriched atmospheres can lead to fire and explosion risk. Oxygen enrichment will significantly increase the flammability of combustible material such as clothing and grease.

3. Fire hazard: There may be an explosive/flammable atmosphere due to flammable liquids, gases or combustible material which if ignited would lead to fire or explosion.

Chemical exposures due to skin contact or ingestion as well as inhalation can cause irritation, burning, injury or death, depending on the concentration and other property of Chemicals

Process-related hazards such as residual chemicals. Material leakage form vents, flanges, process lines or material previously stored

4. Physical and other hazards : 

Noise above permissible limit , heat/cold, radiation, vibration, electrical, failure to use of 24volts hand lamp, tools and other objects dropped form overhead

Precautions to taken before starting Confined space Work: 

1. Atmosphere Testing And Monitoring: 

Acceptable ranges of Oxygen, Combustible and Toxic substance

Parameter             Acceptable range 

Oxygen :                 <19.5% or >23.5%

Flammability:          >10% lower Explosive                                           limit (LFL)

Toxicity:                    >50% threshold limit                                            value (TLV)

2. The equipment to be worked on shall be mechanically isolated from all connecting lines.

3. The Equipment should be properly flushed, drained, decontaminated, free form vapours, gases or any other combustible material

4. The equipment should be depressurized

5. The equipment or atmosphere temperature less than 50°C 

6. All workers must Use of suitable type of Personal Protective Equipment (PPE) Such as SCBA, Safety Goggles, Safety Shoes, hand gloves etc.

7. Provide Ventilation: 

If Natural ventilation is not sufficient to maintain the air quality. provide Mechanical ventilation such as blowers, fans etc.

8. Safe access and escape arrangements for emergency situations or rescue team 

9. Provide adequate lighting in the confined space( use of 24 volts lamp)

4. Excavation work Permit: 

Excavation work generally means work

involving the removal of soil or rock from earth to form an open face, hole or cavity, using tools, machinery or explosives.

Examples of Excavation Work Permit: 

Excavation used for basements, installation and maintenance of underground tanks, pipelines, piling or any other equipment.

Hazards and Precautions of Excavation Work Permit: 

1. Provide a warning system such as Barrication

2. Sloping and shoring of the excavation sides.

3. Supporting the sides of the excavation; or

Placing a shield between the side of the excavation and the work area.

4. Workers and work equipment can fall into an excavated area. This may causes serious injury to workers.

5. If there are any hazardous conditions present, the employer must ensure that adequate precautions are taken such as use of SCBA and other PPE

6. Keep heavy equipment away from Excavation sides

7. Test for atmospheric hazards such as low oxygen, hazardous fumes, and toxic gases when workers are more than 4 feet deep.

5. Height Work Permit: 

Height work is defined as any work where no permanent platform such as handrail available for doing work safely, where the risk of fall hazards or the person could be injured if they fell from that place .

Any work at height of 1.8 meter or more from the ground level or floor( Permanent Platform).

Examples Of Height Work: 

Working on a ladders, confined spaces, on roofs, on elevated structures, tanks etc.

Precautions to taken before starting the height work: 

1. Proper scaffolds and/or temporary work platforms shall be provided for working

at height at elevations 1.8 meters or more where no permanent work platform is

available to work safely.

2. Full body harness with double lanyard shall be worn when work requires persons closer than 1.8 meters from roof edge without parapets, or floor opening

3. Proper area barricading to prevent people walking across below the working

area

4. Use of safety net when required

5. Retractable fall arrester shall be used for climbing as well as coming down the

ladder where ever it is required.

6. Self-Retractable lifelines can be used as a method of providing vertical lifelines

for ladders, scaffolds, etc.

7. While working in confined space at height use of rescue harness and self- retractable full body harness is must.

8. Lifelines, if used, shall it be of sufficient strength to withstand the large forces

involved in falls. 

Hazards Of Height Work:

The main hazards of working at height is fall hazards. If a Persons to work from elevations 1.8 meters or more from ground level having risk of Serious injuries due to fall

6. Electrical work permit: 

Electrical work permit required for any work on electrical distribution, generation and storage system such as transformer, batteries, switch yard, panels etc.

Precautions to taken before starting Electrical work permit: 

1. The equipment properly electrically isolated( De-energised) 

2. Always use insulated tools while working.

3. Warnings boards or Electrical isolation tag Danger- "Do not operate, man at Work" Should provide.

4. All the equipment should be properly earthed before starting maintenance job.

5. Always use appropriate insulated rubber gloves and other PPE while working on electrical circuit.

Hazards Of Electrical Work Permit: 

1. contact with live parts, wire or equipment causing shock and burns. Electrical burns, one of the most serious, painful and disfiguring of all burns.

2. fire or explosion may be happen when electricity could be the source of ignition in a potentially flammable or explosive atmosphere

If you have any doubts, please comment below,

Thank You.

Read More: What Is LEL, UEL, TLV, STEL, IDLH and Flash Point Chemical Industry Interview Q&A-Job Availables

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