12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estonia3.4 Test result of pipe prolonging whilepressurizingThe test results are as follows:Table 1. – Test result of pipe prolonging while pressurizingDistancebeforepressurizingDistance afterpressurizingTests1 2 3 Average[mm] [mm] [mm] [mm]4 360 4 360 4 360 4 3604 365 4 365 4 365 4 365The diagram (Fig. 23) below contains two different TDRmeasurements. It is one graph per wire and test. Ifthere are no changes in the impedance there are nochanges in the profile in the graph. And there are nochanges in the profiles.The pressure that was used was approximately1400 kPa. The test results show that a single pipecasaflex prolongs itself 100*5/4360 = 0,11%.his could be compared to the more common steel pipefor district heating. If that pipe would be loaded with athermal load of 100 ºC it would prolong itself 0,12%.The force with which the casaflex pipe is expandingbecause of the inner pressure would for 11400 kPa be7,3 kN according to the supplier. That would mean thatthe diameter would be 81,5mm. In real life the diameterwas measured to be 83,9 mm. The corresponding forcefor the diameter 83,9 mm would be 7,7 kN.If the pressure would have been 1 600 kPa and thediameter would have been 81,5 mm then thecorresponding force would have been 8,3 kN.This could again be compared to the steel pipe with thethermal load of 100 ºC. This pipe would prolong itselfwith the force of 164,9 kN.So the casaflex pipe expands with a force that isapproximately 100*8,3/164,9 = 5,0% of the force from asteel pipe when heated 100 ºC.Looking at Fig. 22, case a), one sees that the innerforce (axial load) that the expanding force has toovercome is negligible.3.5 Test results from the leak test of the pipecasingDifferent TDR graphs have been made in May 2009, inJune 2009 and in April 2010.Through metering the resistance and making TDRgraphs it is proven that:a) It can be done to connect the two differentsystems (The Nordic System and the HagenukSystem).b) There are no leaks in the test area, neither inthe supply pipe nor in the return pipe.Fig.23 TDR graph for the supply pipe.3.6 The results from the test of degree ofcompaction of the streetThe different tests were plotted in diagrams and gavethe different Young‘s modulus E v1 and E v2 for differentplaces. The places were documented in a photo. Theresults can be read in the table below.Table 2. - Results from test of degree of compactionSpotE v1(MN/m 2 )E v2(MN/m 2 )E v2/E v11 38,75 91,44 2,362 18,23 25,25 1,393 61,29 126,4 2,064 51,53 100,65 1,955 29,30 70,08 2,39For every test the division E v2 /E v1 are approved. Spot 2E v2 is to low but the other four spots are approved sooverall the test is ok.3.7 Results from the visual control of the surface ofthe streetThe strength of the roadThere was no change in the surface of the street due tothe shallow laying of the district heating pipe what soever the first eleven months. In spring after anunordinary cold winter one could see a small crack(approximately 12 cm) in the street along the pipesextension. As this article is getting written it is notinvestigated why the crack has appeared nor of theimportance of it. The street has much worse injuriesfrom frost action damages outside the test area.102