PIPE SYSTEMS


INDUSTRY NEWS


The advantages of ‘plastic’ piping By Sandy Fairley* I 8 8


s the UK missing a trick when it comes to specifying the pipework associated with the country’s growing enthusiasm for district heating schemes (DHS)? Conventionally, district heating applications use steel piping, but there is growing evidence that the use of pre-insulated ‘plastic’ piping can offer significant advantages when taking heat loss and overall system life cycle cost into account.


Numerous research projects have pointed to the advantages of products such as Flexalen – the plastic system that can reduce heat loss potential over steel piping. Its use has the ability to reduce boiler source


July 2014


temperature (and enhance efficiency) and to commit to more extended replacement schedules because plastic networks do not suffer from the same corrosive limitations as steel.


This creates a number of benefits for scheme owners and operators – improved overall energy efficiency, lower long- term system life cycle costs and extended operational periods between pipe replacements. The enduring truth is that steel and hot water do not make comfortable bed fellows, but with the superior flow characteristic of plastics resulting in the use of smaller pipes and improved heat


loss performance, source temperatures can be reduced to the point where plastic networks are now a viable alternative to conventional rigid steel pipework. Add in the greater flexibility in site storage, laying and connecting and it’s no wonder that plastic is now on the radar for scheme specifiers and operators. As we are aware, most district heating schemes in the UK use steel pipework to meet the high operational temperatures that are needed to compensate for heat loss over often quite large distances. However, this inevitably means that city centre schemes need replacing every ten years or so


because the system pipework will have corroded, with the corresponding risk of leakage. In the past, there has often been resistance to the use of ‘plastic’ in UK district heating schemes, but the wide diversity of such schemes means that a re-evaluation of new generation flexible pre-insulated piping is required, if not for primary ring mains around a city, then certainly for secondary and tertiary lower temperature connections.


There have been numerous studies about the value of this maturing pipe technology, focused mainly on its flexibility and it advantageous heat loss properties, resulting from the


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