Premium Content
Permit to Work Systems
Permit to Work Systems
This Technical Measurement Document relates to the permit-to-work systems that are required to control work on chemical plants, such as maintenance activities, and thereby avoid a probability of serious accident.
Work permits are a vital tool because they provide a mechanism for identifying, reviewing and controlling hazards associated with the work to be performed in the process plant. Work Permits for safe work practices are required in the following situations:
a. Entry to a confined space (e.g. Batch Reactor, Pressure Vessel)
b. Work in or around confined spaces
c. Working at heights
d. Excavation.
e. Hot work.
There are many advantages to using a permit to work system as it:
a. Ascertains that the right persons are authorized to do the job. This designated work may be for specific work or any work in a specific area.
b. It tells the people precisely the nature and scope of the work, as well as the hazards associated while performing the activity. It also specifies any constraints on the scope of the work and the time duration in which the job can be completed.
c. specifies the safeguards that must be followed, including safe separation from potential hazards, such as exposure to chemicals, etc.
d. ensures the person in-charge of the plant or in-charge of the area must be aware of all the work being done under the work permit system.
e. provides a systematic system of control and record shows the nature of the work to be performed against which the safety precautions required which will be checked by a competent authority before performance of the work.
f. provides for the suitable display of permits in the work area.
g. Shows a specific time till the work to be performed.
h. provides a handover procedure for use when the permit is issued for a longer duration ie more than one shift.
i. provides a closure of the work permit to ensure that part of the plant/utilities affected by the work are now in a safe condition and ready to use.
The issuer of the work permit generally area manager should be properly trained in hazard identification, risk assessment and risk control techniques.
Before issuing a safe work permit, the issuer of the work permit and recipient should take a visit of that area and consider all potential hazards associated in the area of work such as presence of hazard material, pressure, temperature, fumes, electrical power, height, restricted space, confined space and others.
The work permit should clearly spell out the precautions to be taken while carrying out the work and identifying/mentioning of the risk control measures in the work permit, such as:
a. isolation of the equipment.
b. decontamination of the equipment with analysis.
c. working in confined spaces.
d. hot work.
e. working at heights
f. excavation and building work, etc
The issuer of a work permit should ensure that the person is competent enough to perform the required work.
The issuer should clearly explain the hazards and the control measures to the recipients associated with the job activity prior to the commencement of the work and issuer of the work permit shall ensure that all the potential risks are isolated and control measures shall be in place. The recipient shall confirm that the safe work procedures associated with the job are thoroughly understood, also the recipients should acknowledge their understanding/consent about the job activity in writing before commences the work.
After the work permit has been issued, the work should be carried out in-line with the safe work permit guidelines. After completion of the job, the work permit should be returned to the issuer and mention as closed after the job is completed.
Some contributory factors for an assessor to consider concerning the Work Permit System.
The Safety Report should address the following points:
• Whether employees have been adequately informed, instructed, trained, and monitored in order to reduce the risk of a human error during the operation of the work permit system.
• Whether the work permit includes adequate safety guidelines, work instructions, use of correct PPE, etc.
• Whether the work permit provides enough information about the type of work required like vessel entry, hot/cold work, working at height, etc.
• Whether the employees supervising the maintenance work are identified as per the work permit system and that the work is properly monitored by a experienced and responsible person.
• Whether adequate precautions are taken prior to initiating a work permit like isolation, draining, flushing, etc.
• Whether employees are aware of the type of environment they are going to work during the operation of a work permit (e.g flammable, corrosive, explosive, zones 0, 1 & 2, electricity supplies).
• Whether the plant in-charge is aware of the type of work involved and how long it is likely to take and
• Whether the work permit system addresses a proper formal procedure whereby the job activity is handed back to the operation.
Safe working in confined spaces:
Types of equipment that may be a confined space can include:
air conditioning ducts, boilers, batch evaporator, filter drums, pipes, pits, trenches, storage tanks, etc
A safe work permit system “confined space work permit” must be issued to ensure that all risks associated with entry into a confined space are assessed successfully and the risks associated with the confined entry are minimized or, where ever possible, eliminated. The issuer of safe work permits must be trained and have sufficient knowledge wrt to confined space entry procedures and risk assessment techniques.
Some of the hazards associated with confined spaces include:
oxygen % level, organic content, toxic chemicals, protruding objects, high temperature, electric shock, rotating parts, visibility, smell, etc
Possible control measures for work in confined spaces:
Procedures are required that address all hazards likely to be encountered before a safe work permit is completed and person(s) are permitted to enter the confined space. Issues to be considered include:
identification of the authorized person, risk assessment, isolation procedures, atmospheric testing and the need for air purging, lighting and ventilation, identification of a stand-by person, rescue procedures and first aid, signs and barriers to prevent access to unauthorized persons, training of all persons working in or involved with confined space entry, check for the presence of chemicals, etc.
No safe work permit should be issued until all measures are implemented and the persons entering the confined space are briefed about the conditions of entry and objective of entry.