Technologies and Production Routes

Some success has been demonstrated by research at Queens University, Belfast using rotational moulding for small production runs of large thick walled pressure pipefittings [80]. The advantage of this process is that it does not have the high tooling costs of 

If appropriate fittings are not available in the same material as the pipe it then becomes necessary to use fittings in an alternative material and then some care must be exercised in the design of transition connection. For example, before plastic valves which could be welded to PE pipes became available it was necessary to employ metal valves with a mechanical connecting joint. 

PVC pipes can be solvent welded but mostly they are joined by mechanical compression or push-fit connectors. Various designs exist and the most successful are capable of connecting any type of pipe within specified diameter range. Some mechanical fittings for softer materials such as PE use compression of the pipe wall into grooves as a means of sealing the joint. This technique is unsuited to harder plastics such as PVC. The multiple application connectors rely upon compression of a separate elastomeric seal. 

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