This page contains a Flash digital edition of a book.
DISTRICT HEATING INDUSTRY NEWS


Taking the stress out of pipe networks


S


ass from the woodworking industry ed in A2A’s waste-to-energy plant in which supplies heat to approximately 65% of the Italian city’s inhabitants.


foremost in orchestrating local heating and cooling strategy”. Fiona Riddoch, Director of COGEN Europe, added: “By looking at different parts of the energy demand and supply in isolation, we may find solutions, but not the cheapest, fastest and best ones. Given the EU’s growing concerns on competitiveness, addressing heating and cooling by taking an integrated view of the energy system is of paramount importance to help European industry stay competitive. The Heat Coalition, which incorporates 11 European organisations with a stake in the heating and cooling sector, believes that the future energy system must be smart, highly integrated and multi-directional, where supply and end-use technologies work as one. This is why full recognition of heating and cooling is imperative for a successful EU climate and energy policy framework for 2030 and beyond.


More information from www.euroheat.org


erious concerns about the lack of awareness regarding the effects of thermal expansion


on pre-insulated pipe networks has been raised by CPV Ltd, a leading UK manufacturer of district heating pipe systems. Mark Whettall, Managing Director, explained: “It’s all too common for civil works to commence on site and hit an unforeseen obstruction in the ground that requires a deviation from the planned route. These changes, which are often made on the hoof, can seriously affect the integrity of a system’s performance. Although they may not be apparent straight away, as soon as the system is operational and the temperature cycles commence, the stress levels increase dramatically and in the worst cases, stress fatigue can occur.


“This, of course, will invariably disrupt the supply to consumers and necessitate a costly repair to be made – something that could have all too easily been avoided. “Something as simple as adding in an unplanned branch connection can also seriously impair a system’s ability to cope with the huge forces exerted on the pipe from thermal expansion. To put it into context, a 200 metre length of buried DN250mm pre-insulated steel pipe, heated to an operating temperature of 120°C will expand by around 150mm, exerting a force of some 171MPa – the equivalent of 52 tonnes.”


Experienced district heating network designers and manufacturers should always be able to assist the on-site teams with calculating the effects that these system changes can have so that necessary


steps can be taken to ensure that the thermal expansion stays within the requirements of both the manufacturers’ recommendations and the requirements of the EN 13941 standards for the design and installation of pre-insulated bonded pipe systems for district heating.


Whettall continued: “It’s not rocket science, it’s just sound engineering design and by using advanced stress analysis tools such as the industry-leading sisKMR software package, as a manufacturer we’re able to analyse and correct a client’s proposed design so that its performance and life


expectancy are maximised. “In an ideal situation, contractors should pre-stress a pre-insulated pipe system by heating the network before it’s buried, then backfilling and compacting the trenches whilst the system remains heated in order to reduce the initial stress to acceptable levels. Unfortunately though, site conditions, particularly when working in urban environments, often prevent this approach so we have to use other methods of dealing with expansion as dictated by our stress analysis calculations.”


More information from www.cpv.co.uk


September 2013 7 7


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16