Permit To Work (PTW) refers to management systems used to ensure that work is done safely and efficiently. These are used in hazardous industries and involve procedures to request, review, authorise, document and most importantly, de-conflict tasks to be carried out by front line workers. Permit to work is an essential part of (COW), the integrated management of business critical maintenance processes. Control of work is made up of permit to work, hazard identification and
(RA), and isolation management (IM). [ Permit to work is a core element of (ISSOW) systems, that along with and isolation planning, enable as low as reasonably practicable (ALARP) reduction of unsafe activities in non-trivial work environments. Permit to work adherence is essential in. Instructions or procedures are often adequate for most work activities, but some require extra care. A permit to work system is a formal system stating exactly what work is to be done, where, and when. A responsible person should assess the work and check safety at each stage. The people doing the job sign the permit to show that they understand the risks and precautions necessary. Permits are effectively a means of communication between site management, plant supervisors and operators, and those who carry out the work. Examples of high-risk jobs where a written permit to work procedure may need to be used include hot work such as welding, vessel entry, cutting into pipes carrying hazardous substances, diving in the vicinity of intake openings, and work that requires electrical or mechanical isolation.
It is also a means of coordinating different work activities to avoid conflicts. A permit to work is not a replacement for robust risk assessment, but can help provide context for the risk of work to be done. Studies by the UK Health and Safety Executive have shown that the most significant cause of the maintenance related accidents in the UK chemical industry was a failure to implement of effective permit to work systems. Common failures in control of work systems are a failure to follow the permit to work or isolation management procedures, risk assessments that are not suitable and sufficient to identify the risks, and/or the control measures and a combination of the two. This Technical Measure Document refers to permit to work systems required to control work such as maintenance activities on chemical plant and so prevent a major accident. The relevant Level 2 Criteria are and Contents of the work permits. Communication failure during the use of a work permit system. Whether staff have been sufficiently informed, instructed, trained and supervised to minimise a potential human failing during operation of the work permit system; Whether the work permit system includes sufficient safety information, maintenance instructions, correct PPE and equipment for use; Whether the work permit contains sufficient information about the type of work required (Equipment removal, excavation, hot/cold work, repairing seals, vessel entry, waste disposal, isolation); Whether the work permit system is managed, regularly inspected and reviewed; Human factors (stress, fatigue, shift work, attitude); Whether sufficient precautions are taken prior to initiating a work permit (isolation, draining, flushing, environmental monitoring, risk assessments, communication, time allotted for the work); Whether staff are aware of the type of environment they are working in during the operation of a work permit (flammable, corrosive, explosive, zones 0, 1 2, electricity supplies); Whether the work permit system involves a formal procedure whereby the maintained plant or equipment is handed back to operation.
Failure to recognise the hazards where work is carried out (e. g. flammable substances); Introduction of ignition source in controlled flameproof area (e. g. welding, non spark-proof tools, non-intrinsically safe equipment used in intrinsically safe zones); Terms of work permit not adhered to (e. g. failure to isolate plant and/or drain lines of hazardous substances); Insufficient monitoring of the work permit system. HS(G)5 Hot work : welding and cutting on plant containing flammable materials, HSE (Not in current HSE list). Paragraph 3 refers to the precautionary measures needed when welding in areas that could be potentially flammable by planning and controlling the task using a work permit system. Paragraph 72 refers to the importance of management controlling the work permit system. Paragraph 73 refers to the principles that should be followed when operating a work permit system. , HSE, 1989. Paragraph 27 refers to conscious incompetence whereby an employee consciously refused to follow the work permit system to help an operator.
A breathing line was not assessed and an operator inhaled nitrogen instead of air. Had the work permit system been managed properly then the event would not have occurred. , HSE, 1998. Paragraph 48 illustrates a permit to work system and summarises its expected contents. HS(G)64 Assessment of fire hazards from solid materials and the precautions required for their safe storage and use, HSE, 1991. Paragraph 28 refers to the need for a work permit system if a source of ignition is introduced such as welding, cutting or grinding. The system should contain any fire precautions necessary. , HSE, 1997. The section called; `Devising Risk Control Systems RCSs\’ under Inset 11, illustrates the permit to work system as an example of a management control loop i. e. plan, do, check and act. It demonstrates how risks in the work place can be reduced if they are controlled and managed. HS(G)77 COSHH and peripatetic workers, HSE, 1992 Paragraph 19 refers to the inclusion of a work permit system in a COSHH assessment. It highlights the importance of safeguarding against risk when carrying out work on a chemical plant. , Oil Industry Advisory Committee, HSC, 1997. IND(G) 98 (Rev 3) Permit-to-work systems, Free copy available at HSE Books online, HSE, 1997. Guidance on permit-to-work systems in the petroleum industry. , HSE, 1997 Loss Prevention in the Process Industries: Hazard Identification, Assessment and Control. Frank P Lees 1996, 2nd Edition, vol 2 ch. 20 and 21. Published by Butterworth Heinemann.