Permits to work

Bolted joints are friendlier than quick-release couplings. The former are usually dismantled by a fitter after issue of a permit to work. One person prepares the equipment and another person opens it up the issue of the permit provides an opportunity to check that the correct precautions have been taken. In addition, if the joints are unbolted correctly, any trapped pressure is immediately apparent and the joint can be remade or the pressure allowed to blow off. In contrast, many accidents have occurred because operators opened up equipment which was under pressure, without independent consideration of the hazards, using quick-release couphngs. There are, however, designs of quick-release couphngs which give the operator a second chance. 

Enter any confined space, e.g. any tanks or pits, except in accordance with a permit-to-work system. 

Total enclosure may be in the form of a room with grilles to facilitate air flow this functions as a hood and operates under a slight negative pressure with controls located externally. Entry is restricted and usually entails use of comprehensive personal protective equipment. Ancillary requirements may include air filters/scmbbers, atmospheric monitoring, decontamination procedures and a permit-to-work system (see page 417). 

See also permit-to-work systems and operating procedures)... 

See also maintenance, permit-to-work systems, personal protection, site restrictions, access, modifications, personal hygiene etc.)... 

A permit-to-work system is essential to control entry into confined spaces, e.g. tanks, reactors or underground chambers. Requirements... 

No entry without a specific permit-to-work authorizing the work entry without a permit is forbidden except for rescue purposes... 

Other situations for which permits-to-work are required include ... 

THE PERMIT TO WORK IS NOW CANCELLED. A NEW PERMIT WILL BE REOUIRED IE WORK IS TO CONTINUE... 

Are staff trained in the use of the permit-to-work system and its significance ... 

Chemical and Process Industries Training Board (1977) Permit to Work Systems, CAPITB-16, London. Cheremismoff, P.N. (1992) Waste Incineration Handbook, Butterworth-Heinemann, Oxford. 

Permits-to-work and you. (An introduction for workers m the petroleum industry). Revised 1991 Asbestos does your company work with asbestos Bitumen boilers in construction fire hazards Elammable liquids on construction sites... 

Are you involved m the transport of dangerous substances by road (replaced by IND(G)234L) COSHH and Section 6 of the Health and Safety at Work Act Permit-to-work systems. (Chemical manufacturing)... 

We put a lot of effort into improving safety by adding protective equipment onto our plants, new and old gas detectors, emergency isolation valves, interlocks, steam curtains, fire insulation, catchment pits for LPG storage tanks, and so on. We also introduced new procedures, such as hazard and operability studies and modification control, or persuaded people to follow old ones, such as permits-to-work and audits. 

The pump had been awaiting repair for several days when a permit-to-work was issued at 8 a.m. on the day of the fire. The foreman who issued the permit should have checked ahead of time that the pump suction and delivery valves were shut and the drain valve open. He claimed that he did so. Either his recollection was incorrect or, after he inspected the valves and before work started, someone closed the drain valve and opened the suction valve. When the valves were closed, there was no indication—on them—of why they were closed. An operator might have opened the suction valve and shut the drain valve so that the pump could be put on line quickly if required. 

It is usual, before a piece of equipment is maintained, to give the maintenance team a permit-to-work that sets out ... 

Once a vessel has been connected up to any process or service line, the full permit-to-work and entry procedure should be followed. In the present case, this should have started eight weeks before the incident. And the nitrogen line should have been disconnected or slip-plated where it entered the vessel. 

When the plant is still in the hands of construction, the nonual permit-to-work procedure is not necessary, but an entry permit system should be in force. Before anyone enters a vessel, it should be inspected by a competent, experienced person who will certify that it is isolated and free from danger. While a tank is being built, when the walls reach a certain height (say, greater than the diameter) the... 

Permits-to-work could be prepared and stored on a computer. The saving in effort would not be great, but additional functions are now possible. For example ... 

Ignition in 23% of the cases where this occurred, the source was unknown in about a third of the incidents in which the source was known, it was auto-ignition. Other common sources were flames, hot surfaces, sparks, lighming, static electricity and electrical equipment. In many cases conditions changed after a permit-to-work had been issued (see Section 1.3.2). 

Which often lead to violations. The following deficiencies may occur in any applications of procedures, from operating instructions to permit to work systems ... 

These are dranges in the system over time due to factors such as wear and deterioration of hardware, and also the erosion of hmnan systems such as supervision and permits to work. 

The root causes for this critical event both concern the operations department and the service department who ran the contractor maintenance team. The operations department (i.e., the day shift operations supervisor) failed to provide adequate supervision and instructions to the contractor team. Explanations of the nature of the permit-to-work systems (i.e., the need to report back at end of shift) should have been given, and the possibility and implications of work not being completed before the end of the shift should have been considered by both parties. 

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