A Work Permit System is a structured procedure implemented by organizations to authorize and control hazardous or non-routine tasks. It ensures that work is conducted safely by issuing documented permission with specific instructions and safety procedures. It is also called Permit to Work (PTW) system.
Here are the key components of a PTW system:
- Authorization: Approval from designated personnel at different stages of permit management, ensuring that only authorized individuals can carry out the task.
- Roles and Responsibilities: Clearly defined roles for everyone involved in the task, outlining their responsibilities and obligations to maintain safety standards.
- Hazard Identification: A comprehensive assessment of potential hazards associated with the task, along with corresponding preventive measures to mitigate risks and ensure worker safety.
- Task Description: Detailed information about the nature of the job, including its scope, location, timeline, and step-by-step instructions for its execution.
- Risk Assessment: Thorough safety protocols tailored to the specific job, which may include site audits, equipment checks, personnel training, and other measures to minimize risks.
- Status Records: A system to track the status of the permit, indicating whether it is open, closed, canceled, revoked, or reissued, to ensure that work activities are conducted in compliance with safety regulations.
By incorporating these components into a Permit to Work system, organizations can effectively manage and control hazardous tasks, prioritize safety, and minimize the risk of accidents and injuries in the workplace.
1. Work Permit System Introduction.
The Work Permit System is an important tool for safety in Plants and refineries and other commercial building projects. The Work Permit System is described covering various aspects like when a work permit is required, types of permits, responsibilities, check lists, validity etc.
The success of a Work Permit System depends upon the training, motivation and participation of all individuals concerned with its implementation. Since several maintenance/ construction jobs are often carried out with assistance from contractors, it is essential to provide sufficient exposure to contractor and his employees as well.
If the work has to be performed in a hydrocarbon processing/ handling installation by any person other than the operating personnel of that area, a duly authorised written permit shall be obtained by the person/agency executing the work before commencement of the work. However, even for operating personnel, when work has to be performed outside their normal routine, an exclusive permit to that effect by the authorised person shall be obtained.
2. Scope of Work Permit System.
The Work Permit System shall cover all hydrocarbon processing / handling installations such as onshore /offshore processing platforms, gas treating units, crude oil terminals, refineries, pipelines, marketing installations and LPG bottling plants and power plants.
3. Definitions.
a) Hot Work: Hot Work is an activity which may produce enough heat to ignite a flammable air – hydrocarbon mixture or a flammable substance.
b) Cold Work: Cold Work is an activity which does not produce sufficient heat to ignite a flammable air – hydrocarbon mixture or a flammable substance.
4. Types of Work Permits.
Based on the nature, the work shall be undertaken either under Hot Work Permit or Cold Work Permit.
The two types of permits, one for cold work and the other for hot work are the minimum requirements which must be fulfilled before commencing work. For jobs like excavation, road/dyke cutting, electrical lockout / energising etc., where the work permit issuing authority may have to take clearances from other sections/ personnel, organisations may introduce supplementary formats for these purposes, if they consider it necessary. Format for electrical lockout/ energizing is shown in figure.
Hot Work Permit.
Cold Work Permit.
Electrical Lockout / Energizing Form.
Radiography must be carried out when occupancy is least. For precautions to be taken during radiography, on “Personal Protective Equipment”.
In addition to the regular work permit, supplementary permits as required by the local statutory bodies are also to be issued.
5. Procedure for Work Permit System.
Following is the procedure for the implementation of Work Permit System :
(a) The Work Permit System shall always operate on “Owner – In-charge” concept. (Example: Process Unit-Shift In-charge; Laboratory-Chief Chemist; Depot-Depot Manager; Pipelines Installation- Shift In-charge). The concerned management shall issue the appropriate authority limits for various installations and type of permits based on this concept.
(b) The permit shall be in printed form.
(c) Separate forms shall be used for Hot Work and Cold Work.
(d) A system of colour coding is recommended to identify two types of permits. The recommended colours are pink for Hot Work Permit and yellow for Cold Work Permit. All permits shall be serially numbered.
(e) Hot Work Permit shall be in four copies. The original shall be in pink colour and other copies shall have the word “COPY” printed in large pink letters. Cold Work Permit shall be in two copies. The Original shall be in yellow colour and the copy shall have the word “COPY” printed in large yellow letters.
(f) It is recommended that both Hot Work Permit as well as Cold Work Permit be made in the form of books with tear-off facility. In the case of Hot Work Permit, the authorised Original copy shall be given to the receiver, the Duplicate to the Fire Section, Triplicate to Safety Section and Quadruplicate retained in the book. In case of Cold Work Permit, the authorised Original shall be issued to the receiver, retaining the Duplicate in the book.
It is recommended that plot plans of the installation and the operating blocks should be displayed in the Fire and concerned Unit Control Rooms respectively and site of hot jobs under progress should be indicated on these plot plans with red pins. This helps the incoming supervisor /s (both in Fire and Operating Departments) to get a quick idea of the hot jobs being undertaken and help in identifying the areas which require inspection / attention, depending upon the criticality of the area and the job.
The Safety Officer/Fire Officer / Officer authorised will make periodic check of the Hot Work Sites and see that the work is being carried out as per conditions laid down in the Hot Work Permit. At any point of time, if he considers that the conditions are not safe enough for the work, he may suspend the work and inform the Work Permit Issuing Authority to restore the safe conditions so that work can be restarted.
(g) For simplification of procedure, Hot Work Permit also covers permission for vessel entry, vessel boxing-up and excavation. All activities outside the scope of Hot Work Permit shall be covered by Cold Work Permit.
(h) No hot/cold work shall be undertaken without a work permit except in the areas pre-determined and designated by the owner-in-charge. All work permits shall be issued by the person who is designated as responsible person for the operation of the area where work is to be carried out. In respect of work permits for handling highly critical types of work and also for long duration work such as in construction jobs in a running installation, the authorising level should be elevated.
- The work may be planned to be done either departmentally or through a contractor. In either case, the work permit should be received and signed by the maintenance / project /construction supervisor of the company as he is responsible for the work of the contractor also. Where no such independent supervisor exists, for example in small installations, the owner-in-charge can issue the permit to the contractor’s supervisor directly and obtain his signature.
(j) Permit should be issued only for a single shift and its validity should expire at the termination of the shift. However, where the work has to be continued, the same permit may be revalidated in the succeeding shift, by authorised person after satisfying the normal checks.
In instances like plant turn around or an activity where work is of continuous nature involving round the clock activity, blanket
Hot Work Permit could be given if the owner-in-charge is fully satisfied that the conditions are totally safe for the multiple jobs to be performed. But this should not be resorted to, especially in highly integrated units.
Even when construction activity has to be undertaken in non-operating areas in integrated units, it is recommended that approval be obtained from designated senior management for issuing blanket Hot Work Permit.
(k) As a pre-requisite to issue permit, particularly in the case of hot work/vessel entry permit, gas test for hydrocarbons / oxygen deficiency / toxic gases shall be conducted as applicable.
(l) Where gas-free conditions are not fully ensured for the duration of hot work, a system of monitoring either by automatic or by manual periodic verification shall be resorted to depending upon the prevalent conditions of the operating area.
(m) After completion or stoppage of the job, the person to whom the permit was issued, should thoroughly check the area for clearing of debris, removal of temporary electrical installations etc. and then shall sign the work permit and return it to the issuer.
(n) The issuer on receiving back the permit would satisfy himself regarding completion of the job and that the area has been cleaned. Then he shall also sign the permit and keep the records for one month.
6. Checklist Items of Work Permit Forms.
The Checklist Items in the Work Permit Forms are elaborated below to amplify the underlying concepts and highlight their significance:
(i) Equipment / Area inspected.
Equipment or area where work is to be conducted, should be inspected to ensure that it is safe to carry out the work and assess other safety requirements / stipulations. In case of vessel box-up permit, it should be ensured that the work is complete, all personnel are out, no maintenance gear is left behind and debris removed.
(ii) Surrounding area checked / cleaned.
Unsafe conditions for performance of work may arise from surrounding area. It should be cleaned-up to remove flammable material such as oil, rags, grass etc.
(iii) Sewers, Manholes, CBD etc. and Hot Surfaces covered.
Flammable gases may be released from nearby sewers. Hot un-insulated surfaces/pipelines may provide a source of ignition. Therefore, these are to be properly covered to prevent fires.
(iv) Considered hazard from other routine / non-routine operations and persons alerted.
Other activities (routine / non-routine) being carried out near-by which can create conditions unsafe for performance of the permit work, should be taken into consideration and the concerned persons should be alerted accordingly.
(v) Equipment electrically isolated and tagged.
Before issuing permit for mechanical / electrical work in the operating area, it should be ensured that electrical switches are locked-out and cautionary tags duly signed with date and time are attached. Wherever local locking arrangement is provided in the field, the same should be used. Refer format for electrical lockout / energising given in OISD-STD-137 on “Inspection of Electrical Equipment”.
(vi) Running water hose/Portable extinguisher provided.
Running water hose and portable fire extinguisher are required respectively to flush / dilute in case of release of any hazardous chemical or to quench sparks and to put out small fires immediately.
(vii) Fire water system checked for readiness.
In order to meet any contingency, it should be ensured that the fire water system including fire water pumps, storage, network etc. is checked and kept ready for immediate use.
(viii) Equipment blinded / dis-connected / closed / isolated / wedge opened.
Equipment / Vessel, on which the work permit is being issued, should be completely isolated from the rest of the plant with which it is connected during normal operation, in order to ensure that there is no change in the work environment with respect to presence of toxic / flammable gases, liquids, hazardous chemicals etc. in the course of the work.
Blinding is one of the most effective ways of isolation. Blinds should be installed as close to the vessel as possible. If lines cannot be blinded, they should be disconnected and the open ends should be made safe by installing pipe caps/plugs, blind flanges, mud packing etc.
(ix) Equipment properly drained / depressurised.
Equipment under pressure should be depressurised after isolation.This will be followed by draining / purging / water flushing etc. as the case may be.
Equipment containing liquid hydrocarbons should be drained completely. There may be a possibility of overlooking liquid collected in pockets or inaccessible areas such as level gauges, small nozzles / bleeders on vessels, laterals in pipework etc. All low point drains should be in unplugged condition.
(x) Equipment properly steamed/purged.
Purging of equipment (vessels, pipelines, compressors etc.) is done to make them free of flammable hydrocarbons and toxic gases. Steam / Inert Gas is used for gas-freeing of vessels and pipes in refineries and other locations. Other means of purging is by displacement with water and final traces of gas removed by air eductor. All high point vents should be unplugged while purging. Purging may be done continuously or in batches to conserve purge medium. It should be done in a systematic manner to cover the entire equipment/plant and continued till the concentration of toxic / flammable gas is lowered to allowable level.
(xi) Equipment water flushed.
Water flushing is an effective means of cooling, cleaning and even gas-freeing of equipment. It is also employed to remove traces of acids / chemicals. Equipment metallurgy must be considered before using sea / saline water. Sometimes, flushing with demineralised water would be necessary depending upon the metallurgy of the equipment.
(xii) Gas / Oxygen deficiency test done and found OK.
Gas test includes measurement of:
(a) Hydrocarbons by Explosimeter
(b) Oxygen Deficiency by Oxygen Meter
(c) Use of Calibrated Meters
(d) Toxic gases like Hydrogen Sulphide, Carbon Monoxide, Nickel Carbonyl, Chlorine etc. by techniques like Indicator Tube method, Lead Acetate Paper etc.
Measurement of lead in air is required for entering leaded tanks and personal protective equipment shall be worn before entering the tank. Octel/Ethyl regulations are to be followed while handling leaded gasoline tanks.
Gas tests may be specified for vessel entry including open excavation where head of a man will be below ground level and when hot work is being carried out. The person carrying out gas test must wear proper protective gear.
No hot work shall be permitted unless the Explosimeter reading is zero.
Vessel entry, where no hot work is to be carried out, may be permitted if combustible gases are up-to 5% of lower explosive limit (LEL). Entry with an air supplied mask may be permitted with LEL of up to 50%. The oxygen level should be at least 19.5 % vol. and the concentration of toxic gases below the threshold limits.
(xiii) Shield against sparks provided.
In order to protect against welding sparks which can provide ignition in operating areas, shields are to be provided. The shield material should be non-flammable and should be kept wet with water.
(xiv) Proper ventilation and lighting provided.
Where natural ventilation is not available, fans/air eductors are provided. Some types of work like welding may generate fumes. Facilities may be required for the speedy dispersal of these fumes. Only approved reduced voltage extension lights (not exceeding 24 volts) are to be allowed for work inside vessels from consideration of personal safety.
(xv) Proper means of exit provided.
Proper means of exit is required in case of emergencies developed on account of the work or otherwise. Availability of an alternate route of escape should be considered.
(xvi) Precautionary tags / boards provided.
To prevent any unwarranted entry in the work area and also to caution other personnel taking actions which may endanger people working on the permit job, precautionary tags/boards are to be provided like “No Entry” sign on roads or “Caution-Men at Work Inside” on the manhole of a vessel.
(xvii) Portable equipment / Hose nozzles properly grounded.
As a precaution against static electricity generation, portable equipment / hose nozzles e.g. nozzle of a shot / sand blasting gun, are to be grounded. Use of hydrocarbon lines for earthing should be avoided.
(xviii) Standby person provided for vessel entry.
Whenever a person is entering a vessel or work is being carried out in confined space, it may be necessary to keep standby persons (minimum two) at the manhole or entry point holding the rope connected to the safety belt of the person inside. In case of any emergency inside or outside the vessel, the standby will be able to pull the person out.
(xix) Standby personnel provided for fire watch from Process / Maintenance /Contractor/Fire Department.
Depending on the criticality of the job, work permit issuer shall decide the type of standby to be provided i.e. from which department, of which level, how many and also additional fire fighting support facilities.
(xx) Iron Sulphide removed / kept wet.
Pyrophoric substances may be present in operating area / equipment handling hydrocarbon. Iron sulphide scales is the most common pyrophoric substances encountered. These should be either removed to safe locations or kept wet all the time to prevent their auto-ignition.
(xxi) Area cordoned off.
In order to prevent the un-authorised entry of people and to avoid accidents during excavation jobs, work area is to be cordoned off.
(xxii) Precaution against public traffic taken.
In case hot work is to be carried out in close proximity of a public road, for example in the case of a trunk pipeline, it may be desirable to block-off/divert public traffic for the duration of the job as a precautionary measure.
(xxiii) Clearance obtained for excavation from Technical/ concerned departments.
For any excavation work which may affect underground sewers / telephone lines / cables / pipelines etc., Technical Services Dept. and / or other concerned departments, should be consulted for obtaining the co-ordinates and the depth to which excavation can be resorted to, without damaging the existing facilities. Markers should be put around the area where excavation can be done and the depth can be indicated in the work permit.
(xxiv) Clearance obtained for road cutting from Technical / Fire / concerned departments.
Since road cutting can hamper the movement of the fire vehicles, initial clearance should be obtained from Fire Department and final approval from the higher designated authorities. If the road is wide, preferably the road should be cut half at a time. Duration of road cut should be restricted as far as possible.
(xxv) Clearance obtained for dyke cutting..
When the dyke is cut, any mishap in the tank farm can lead to a free flow of oil to outside the bund. A high level authority should be designated for authorising dyke cutting. Further, it should be ensured that dyke would be reconstructed in the shortest possible time. For example, if pipes have to be laid through the dykes, the pipes should be laid quickly and plugged / capped so that the dyke can be closed. Thereafter, balance of pipe fabrication can continue without any risk. Standby personnel should be available at the work site, who should possess a suitable size steel plate for blocking the opening in case of mishap/tank failure. If no work is undertaken in evening and night shifts, invariably the gap should be closed with steel plate and mud packing at the end of day’s work.
(xxvi) Checked Flame / Spark arrestor on mobile equipment.
No vehicle / engine without flame / spark arrestor is permitted in operating areas.
(xxvii) Checked for oil / gas trapped behind lining in equipment.
Before undertaking hot jobs, a check should be done for oil / gas trapped behind lining in the equipment. Many a times oil / gas trapped behind lining depicts itself in the form of swelling and can be confirmed by way of drilling holes.
(xxviii) Welding machine checked for safe location.
Welding machine should be located in a non-hazardous and ventilated area. It should have proper supervision while welding job is in progress. It should be switched off immediately on completion of the job.
(xxix) Checked for earthing/return connection to the equipment being welded.
Before commencing the welding job, ensure that all the cables and earthing connections are as per the standard welding codes / practices.
(xxx) Oxygen and Acetylene cylinders kept outside the vessel / tank.
While performing welding / cutting jobs in confined spaces like vessel / tank, ensure that oxygen and acetylene cylinders are kept outside and hoses for the gases are in good working condition, without any cracks or wrinkles. Also, hoses should be tightly secured at both the ends i.e. the torch and the cylinder.
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