Joints & Joining
Plastic Pipes Conference Association # 2001 Munich
Hill, Wilson, Headford
Butt fusion welding is the most reliable and unobtrusive method of joining PE pipes (and spigot fittings) of virtually any size-except perhaps the smallest where other methods are usually preferred. It is the dominant method of jointing both medium and large pipe sizes, but for different reasons. In medium pipe sizes the ability to supply PE pipe in coils or sticks, suitable for mechanised laying, is enhanced by butt welding as the joint itself does not contribute additional bulk or adverse handling characteristics to the jointed pipe. In larger sizes, the cost of large diameter fittings may be prohibitive for applications requiring many joints, and it is usually more economic to hire a butt fusion welding machine. However, large pipes, necessarily supplied as straight lengths or sticks, are heavy and difficult to manoeuvre at the best of times and the logistics of butt fusion in the field sometimes needs careful consideration. Aside from this the butt welding machine required for large pipe sizes itself is a very large piece of equipment and needs to be supported by an equally large generator. There is therefore a cost break between employing butt fusion or electrofusion fittings, where these are available (currently uti 630 mm), depending on the scheme size and complexity. Clearly all methods of jointing large diameter PE pipes have their place.
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