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 conduction 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 Administrative tool in 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.
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)
The Purpose Of A Permit To Work System
The main purpose of Permit to work is to make the work safer for the maintenance department and provide then 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
- General Work Permit
- Hot Work Permit
- Height Work Permit
- Confined space permit
- Excavation Work Permit
- Electrical Work Permit
- Process interlock bypass permit
- Special Hazard Work Permit
1. General Work Permit | Cold work permit
General work permits also known as cold work permits. The basic definition of General work permit is the job or the work which doesn’t involve work that can be included in Hot work, height work, confined space are considered as cold work. This generally includes the work in which no heat or spark will generate.
Example of Cold work
- Valve changing work
- Painting work
- Gasket changing work
2. Hot Work Permit
If the work which needs to be conducted will generate heat or spark is consider as hot work and for conducting the work, the hot work permit is issued. cutting, welding, soldering, and brazing operations are considered under hot work. In industries, various solvent and flammable chemicals and gases are used for production and another purpose. 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
- Pipe cutting and fabrication work
- Bolt cutting work
The hot work permit is a huge topic hence it is being covered in an individual article which includes hot work procedure 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 are considered as height work and for conducting that work, height work permit needs to be issued. Generally, work having a height of more than 1.9 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 issues that ensure that the men can work safely and have a full-body harness, safety belt which ensures safety.
4. Confined Space Permit
Confined space permit is also known as vessel entry. Industries and some workplace have some equipment and areas falls under Confined space are those are not meant 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 number of checkpoints are available prior to issue vessel entry permit and herare 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 agitator in 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
Confined space entry permit is discussed in detailed including hazards associated with vessel entry permit and explaind with example in OSHA Confined Space Entry permit.
5. Energized Electrical Work Permit | Electrical Work Permit
Work near High tension line, low tension work, 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 accident 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 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, energy isolation of the machine is performed.
6. Excavation work permit
Excavation work means to dig hole, making a pit or removal of soil. This permit is usually required at construction site and in even industries for new project work. Excavation work permit is required if certain work needed to perform below the ground level of depth 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 plant, plant tripping is being provided as a part of process safety and for those interlocks are defined. These interlocks plays an important roles as they provides extra layer of safety in process plants. In running plant if maintenance is to be taken of any process equipment on which interlock is defined, need of interlock bypass is required as it can trip whole plant. In that case, process interlock bypass request forms issues to instrument department by process department to temporarily bypass the interlock.
8. Special Hazard Work Permit
Special hazard work permit and industry and workplace specific, designed based on the hazard present in that particular organization. Link Nuclear power station where the potential hazard is nuclear waster and radiation. In those industries, special hazard work permit are issues which are designed to safeguard person from those hazards
FAQ (Types of Safe Work Permit)
Why do you need a permit to work?
Safety permit act as a safeguard to protect the person working or performing certain task on the equipment. Hence it is mandatory to have permit to work.
Can we work without safety work permit?
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.
What is PTW full form?
PTW stands for Permit to work.
How many types of safety work permits are there?
Primarily there are 4 types of safety work permits i.e. General Work permit, hot work permit, height work permit, 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 Permit Energized Electrical Work Permits are also issued in order to maintain safety for a person performing a task.
This is the detailed information on Permit to Work including the types of safety work permit in industries. If you have any doubt 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 being used in your organization then do share with us and let us know the purpose and application in detail. Interested people can check out other workplace safety article like what are the 4 stages of a fire? and if you are a chemical Engineer then you can check out Cooling Tower Types and Working Principle.