What is PTW in Industries and Types of Safety Work Permit

Types of safety work permit – In chemical Industries, daily different types of breakdown, maintenance of equipment, installation of new equipment, and many other things are going on in the running plant.

There is risk involved in every work being conducted in industries and we had learned in the hierarchy of risk control that we can only reduce the risk and can’t eliminate the risk completely. Work permit comes under the Administrative tool in the safety hierarchy.

If you survey the accident data, you will find various accidents can be avoided, accidents could be prevented if the work permit system was followed. Whether it is a chemical industry, polymer industry, construction site, or any workplace, a work permit plays a vital role in creating a safe working environment and helps to reduce accidents at the workplace.

Types Of Safety Work Permit

If you are a chemical engineer or working in a production/manufacturing department, it is important for you to learn about a safety work permit and which work permit to issue for the particular job. Maintenance department person i.e. Electrical, mechanical, and instrument department person should also know about the permit system and need to know which permit should they want for the particular work.

Today in this article, we are going to learn what is a safety work permit, what is the purpose of the work permit system, the application of permits, and the types of permits to work. This is just an introduction article, In-depth knowledge is required in which all the aspect should be covered. Now let us dive into the permit guide.

What is Permit to Work in Safety (PTW)

PTW stands for Permit-to-work can be defined as written and documented which authorizes persons to perform specific work at a specific place and for a definite time frame. A safety permit helps to reduce the potential hazard to carry out job/work by making the production and maintenance department aware of the work that needed to be carried out.

Permit to work can consider as written communication between the production and maintenance department that all the potential hazards are identified and steps related to reducing the risk have been taken and provide written permission to work. (Reference – Tata Power)

Why would you need a Permit to Work system?

The main purpose of Permit to work is to make the work safer for the maintenance department and provide them with written permission to work. It plays an important role in risk assessment and prevents hazards involved in the job. The main purpose of a safety permit is to control high-risk activities and safeguard the working person from hazards and risks.

Types of Safety Work Permit System

  1. General Work Permit
  2. Hot Work Permit
  3. Height Work Permit
  4. Confined space permit
  5. Excavation Work Permit
  6. Electrical Work Permit
  7. Process interlock bypass permit
  8. Line breaking work permit
  9. Special Hazard Work Permit

1. General Work Permit | Cold work permit

General work permits also known as cold work permits. The basic definition of a General work permit is a job or work that doesn’t involve work that can be included in Hot work, height work, and confined space are considered as cold work. This generally includes the work in which no heat or spark will generate, or working at height.

Example of Cold work

  • Valve changing work
  • Bolt changing of pipe
  • Material shifting work
  • Painting work
  • Gasket changing work

2. Hot Work Permit

Hot Work In Industries

If the work that needs to be conducted will generate heat or spark is considered as hot work and for conducting the work, a hot work permit is issued. cutting, welding, soldering, and brazing operations are considered hot work. In industries, various solvents and flammable chemicals and gases are used for production and other purposes.

While conducting hot work, there is a possibility that heat generated from the work can cause fire to the chemical present in the area and cause fire/explosion in the area. Hence Hot work permit is issued which ensures that there is no flammable material present in the area and another possibility of fire is also eliminated.

Example of Hot work

  • Welding
  • Pipe cutting and fabrication work
  • Grinding
  • Bolt cutting work
  • Forging

The hot work permit is a huge topic hence it is being covered in an individual article that includes hot work procedures and hazards.

3. Height Work Permit

If work needs to be done is at a certain height from the ground level and if the person fell while working can have injury is considered as height work and for conducting that work, a height work permit needs to be issued. Generally, work having a height of more than 1.8 meters comes under height work.

There is always risk involved in the height work as if the men working at height can get injured and even can fatal if fall at a certain position. Hence Height work permit is issued that ensures that the men can work safely and have a full-body harness, and safety belt which ensures safety.

4. Confined Space Permit

A confined space permit is also known as vessel entry. Industries and some workplace have some equipment and areas that fall under Confined space are which are not meant for work person but has a provision for personnel entry to perform a certain task. Confined space entry is considered to be the most critical one hence extra care needs to be taken while issuing a confined space permit. There are a number of checkpoints available prior to issuing vessel entry permit and here are some of them listed

  • Ventilation inside the equipment/vessel
  • Oxygen content
  • Proper lighting
  • Presence of any chemical or gas
  • Deenergized of any equipment present inside the equipment like the agitator in the reactor
  • Applied blind to any input and output stream to the vessel

Example of Confined space work

  • Spark test in the reactor
  • Agitator maintenance and inspection
  • Rubber lining inside the tank
  • Cleaning of reactor, tank, and tower

The confined space entry permit is discussed in detail including hazards associated with vessel entry permit and explained with examples in OSHA Confined Space Entry permit.

5. Energized Electrical Work Permit | Electrical Work Permit

Work near High tension lines, low-tension work, and work near live electrical components de-energized of the equipment should be done to avoid an accident by electric shock. If maintenance work needs to be taken in any process equipment like a pump, bucket elevator, belt conveyor, etc., de-energized of that equipment needs to be done to prevent accidents that can be caused by the running of the machine.

While taking vessel entry into the reactor having agitator inside, de-energized of the agitator is also done to avoid an accident by rotation of the agitator while the person working inside the reactor. If there is a requirement of a person to get inside equipment then the Lockout Tagout procedure is to be followed in which also, and energy isolation of the machine is performed.

6. Excavation work permit

Excavation work means digging hole, making a pit or removal of soil. This permit is usually required at construction sites and in even industries for new project work. An excavation work permit is required if certain work is needed to be performed below the ground level of a depth of more than 1.5m. If the depth is less than 1.5 meters then barricading is mandatory to safeguard the person from getting slipping into the pit.

Excavation work example

  • Cutting or road
  • Digging for foundation
  • underground pipe installation
  • Pit construction

7. Process interlock bypass request form

In an automation plant, DCS and PLC systems are used to operate plant operations and plant parameters are used to control using panels. In automated plants, plant tripping is provided as a part of process safety and for those interlocks are defined. These interlocks play an important role as they provide an extra layer of safety in process plants.

In a running plant if maintenance is to be taken of any process equipment on which the interlock is defined, the need of an interlock bypass is required as it can trip the whole plant. In that case, process interlock bypass request forms are issues to the instrument department by the process department to temporarily bypass the interlock.

8. Special Hazard Work Permit

Special hazard work permits and industry and workplace-specific, designed based on the hazard present in that particular organization. Link Nuclear power stations where the potential hazard is nuclear waste and radiation. In those industries, special hazard work permits are issues which are designed to safeguard people from those hazards

FAQ (Types of Safe Work Permit)

1. Why do you need a permit to work?

Ans – Safety permit act as a safeguard to protect the person working or performing certain tasks on the equipment. Hence it is mandatory to have the permit to work.

2. Can we work without safety work permit?

Ans – Work without work permit is strictly prohibited. Strict actions need to be taken against the person who asked to perform the person and also to the person who caught performing task without work permit.

3. What is PTW full form?

Ans – PTW stands for Permit to work.

4. How many types of safety work permits are there?

Ans – Primarily there are 4 types of safety work permits i.e. General Work permits, hot work permits, height work permits, and confined space work permits. The need of a safety permit depends on the kind of work hence additional work permits like interlock bypass, special hazard work permits, Excavation Work permits Energized Electrical Work Permits are also issued in order to maintain safety for a person performing a task.

5. What are the different types of Permit to Work?

There are a total 8 types of safety work permits,
1. General Work Permit
2. Hot Work Permit
3. Height Work Permit
4. Confined space permit
5. Excavation Work Permit
6. Electrical Work Permit
7. Process interlock bypass permit
8. Special Hazard Work Permit

6. What is the Colour of work permit?

Every industry has different colors of work permits but it is recommended to have an original copy of the work permit in white color and a duplicate copy should be in pink color.

7. What are the types of work permit in construction?

Construction site, as work is to be conducted, a safety work permit is to be issued, and here are the types of work permits on construction site.
1. Hot work permit
2. Height work permit
3. Excavation work permit
4. Cold/ general work permit

Wrapping Up

This is the detailed information on Permit to Work including the types of safety work permit in industries. If you have any doubts regarding the permit system in chemical industries then feel free to use the comment section. Don’t forget to share types of permits used in your industries and if any other types are being used in your organization then do share with us and let us know the purpose and application in detail.

Welcome to your Types of Work Permit Quiz

Who is the safety work permit issuer for Pump PM work?

What is the purpose of an Electrical Work Permit?

What is a safety work permit?

Which of the following is NOT a type of work permit?

When is a Cold Work Permit typically needed?

What is PTW full form?

Work permits are primarily used to:

What does a Hot Work Permit authorize?

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Me - Founder of Chemical Tweak - A Chemical Engineer by profession and a part-time self-trained technology blogger.

8 thoughts on “What is PTW in Industries and Types of Safety Work Permit”

  1. Right, Permit is important for an industry, without permit the work will never be a legal organization, because of some restrictions. It is also assure that the govt has given the permission, if any kind of failure or something, then not only the industry is responsible. Also it gives a reputation to the business.

  2. Was asked to list 10 different types of permit to work order than hot work, cold work, confined space, excavation,work at height. Pls are there others asides these?

    • Here are the types of safety work permits you can list,
      1. Cold work permit | General work permit
      2. Height Work permit
      3. Confined space work permit
      4. Hot work permit
      5. Excavation work permit
      6. Line breaking
      7. Interlock bypass permit
      8. Pneumatic work permit
      9. Radiography
      10. Special hazard permit (used in nuclear plant and other industries)


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