Pipe laying

Incidents causing immediate shutdown, (a) This group covers all incidents where any discharge from a pipe occurred. (b) Faults in pipe laying which were not immediately found and repaired, are included. 

Despite their simplicity, pipelines are highly capital intensive. Not only is pipe laying costly, the cost is split roughly evenly between materials and labour, but provision of compression stations - necessary for mass transport over long distances - can contribute 40% of finally installed capital. Once established, the operations of a pipeline system can cost 5% of the fixed capital per annum. 

Design of Underground Piping. Laying a pipeline in a tunnel (1) reduces the heat losses and insulation costs, (2) does not occupy valuable overhead space, and (3) protects the piping from mechanical injury and freezing. However, it is a good rule to consider some of the disadvan-... 

Figure 8 Pipe Laying in a 3D Assembly. (Unigraphics. Reproduced with permission of Unigraphics Solutions)...

Seismic surveys Pipe laying operations Equipment recovery Rig positioning Hazard location. 

Pipe-laying, pipeline repair and maintenance, pipeline removal, etc. HSE/MCA/ MAIB HSE HSE/MCA/ MAIB HSE... 

Based on turnover value, the largest part of the plastic pipe industry is probably that part concerned with placing the pipes in their position of usage, above or below ground. But this is a very diverse industry and its pipe laying activities cannot be separated from other aspects of civil engineering and building construction. Whilst for some companies pipework may be a trivial proportion of their construction activities, for others it may be their main specialisation. 

In 2008, a fatal accident was reported when a pipe-laying ship dropped a 20 tonne section of pipe onto operations personnel [3]. The location of the accident was not reported but is presumed to be outside UK territorial waters. 

During pipe-laying operations, a system failure in the hydraulic pipe handling system caused two quadmple joints being handled at the same time in two different areas of the tower to drop suddenly. Each piece of pipe was 50 m long with a diameter of 24 inches and weighed approximately 20 tons. 

Just prior to the incident the pipe-laying operation had been stopped. Operators reported a system failure and that the hydraulic power had been lost. Such an occurrence was not particularly unusual and, in line with company procedures, this was investigated immediately. A team of technicians led by the chief electrician tried without success to resolve the problems. After these attempts, a more in-depth analysis was made. It was decided, on the basis of input from the system diagnostics, to perform a memory reset. Following this the system appeared to be running correctly. This was the first time that a full memory reset was requested by the internal diagnostics of the control system during a project operational phase. 

New pipe concepts with multilayer structures, or so-called functional layers, have helped to expand the applications of HOPE. Pipes with special protective layers (on the outside and/or inside) can be laid without a sand bed under some circumstances. This significantly reduces the pipe laying costs. There have also been new developments in joining technology. For example, electric welding fittings up to 700 mm are now available. Electrofusion jointing of PE pipes for gas distribution is also applied. 

In New Zealand trenches over 5 ft (1-6 m) are invariably dug by machine. The movable shoring devices referred to in 15 and known as shields are being accepted as necessary components in the excavation operation. The shields are used to protect workmen either while timbering is being placed or while pipe laying or other work in the trench is being done. Four basic types of shield have been developed. 

There are two main methods of pipe laying (1) buried pipe and (2) aboveground pipe. The heat transfer coefficient largely depends on the type of environment. 

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