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PTW On the evening of 6 July 1988, in the United Kingdom sector of the North Sea, the Piper Alpha Oil Platform caught fire and exploded. Of the 228 persons on board, only 61 survived. The subsequent report by Lord Cullen into this disaster highlighted, among other issues, the criticality of permit to work (PTW) systems in the offshore industry. The principles that govern PTW systems also have applications in downstream, chemical, processing, and other industries. Introduction Oil and gas offshore installations undertake a very wide range of activities. There are often separate departments carrying out operations, drilling, maintenance, modifications, and servicing, all in parallel and in potentially conflicting situations. The platforms can be many miles from land in very hostile environmental conditions. On large platforms, about 200 individuals have to go about their allocated tasks in a safe, methodical, and coordinated manner. Personnel are often spread out in different shift patterns and perform different duties come routine and some non-routine. An orderly mechanism, of which PTW is a key element, is necessary to coordinate these different activities in a safe and controlled manner. PTW is the system established to control and coordinate work, with an emphasis on maintenance, modification, and testing activities conducted in and around operating process units. In PTW, any action performed on critical components is analysed to ensure that the safety requirements of that task and its interface with other tasks are defined, understood, and observed. (In the United States, lockout/tagout systems often perform some of these functions.) Why Are PTW Systems Necessary? Tasks on offshore installations can be divided into two distinct groups: routine and non-routine. During routine activities, a trained and competent operator carries out well-defined tasks within the strict confines of his or her own department boundary. Routine activities embrace such standard operations as:  Gas compression, hydrocarbon separation, and export  Starting and stopping machinery  Opening and closing valves and breakers for process control purposes  Many activities in pressurised accommodation areas Non-routine activities require individual attention to arrangements and precautions. Each task has to be analysed to ensure that those undertaking the job are given specific guidance on the special safety considerations entailed, including interface between routine tasks. Non-routine activities cover a wide range of tasks, including:  Working overside  Opening up machinery  Structural repairs An essential feature of most routine activities is that they are conducted within the full protection of the platform safety mechanisms. Very often in non-routine activities a safety system is inhibited because either it clashes with the task or the task is being carried out on the safety system itself. Another consideration is that routine activities are highly defined, and the safety associated with them can be subject to review long before they are carried out. Non-routine activities are not so highly defined, and their conditions of application require special, individual screening before, during, and after their implementation to assess their impact on the overall platform risk. PTW systems are essentially designed to cover non-routine activities and control the risks associated with the tasks. Any PTW system should contain a clear definition of non-routine tasks and the interface between the PTW system and routine operations. Within the overall safety management system (sometimes referred to as process safety management system), the importance of a properly constituted and correctly applied PTW system cannot be overemphasised. Reducing high-probability, low-consequence incidents (trips and falls) is best handled by direct safety training and awareness. Reducing low-probability, high-consequence accidents may sometimes best be achieved by hardware improvements. It is in the large, critical middle band of medium probability, medium consequence and hence risk where PTW systems can usually offer a significant improvement in safety performance. The depth of the safety improvement zone is a function of factors such as the PTW system's scope and the commitment within the company to the system (see figure at bottom of facing page). Overview of Recent Developments The Cullen report has caused most operating companies to examine in detail their PTW system. There has been a reappraisal of what companies expect from their own PTW system and whether this remains compatible with national and international safety trends. Visibility Great advances have been made in visibility and management commitment over the last few years. Visibility embraces new work-site awareness, enhanced isolation disciplines, and central coordination. Platform Coordinator Much of the pre-Cullen philosophy promoted the assumption that platform work coordination was the responsibility of the most senior person on the platform. Many operating companies now accept that this person needs some assistance in properly addressing coordination. On large installations where several hundred permits are being used with all the attendant safety clearances, support isolations, and interface problems, a full-time platform coordinator is appointed. On smaller platforms, very often a senior supervisor or complex supervisor takes on the duties. Executive responsibility for arranging and authorising a task remains the province of the line command, but the final agreement to proceed is now given by the platform coordinator. The platform coordinator sees the overall picture and will be uniquely aware of any physical, system, or organisational clash between work items. The platform coordinator is a senior personnel position, requiring someone with working knowledge of all the systems and departments on the platform. Progressively it is