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, Estoniadeveloped is called FLEXALEN 600, the improvedversion of the system used by STEWEAG. The systemconsists of a PB (Polybutene) medium pipe and PO(Polyolefin) insulation foam welded to a HDPE (highdensity Polyethylene) outer casing.up to d63 – there trenches can be compared to cableducts. Another fact is that connections are most of thetime only necessary at branches, for sticks trenchesneed to be suitable for execution of the welding and theinsulation process.With a new inline production process it was possible toweld the moisture resistant insulation to the outercasing. The targets of a corrosion proof and moistureresistant insulation were met.Photo no.: 4 Steel compared to FlexalenPhoto no.:3 Flexalen 600 longitudinal cutFLEXALEN has been the first system to pass acertification and 3 rd party control by KIWA, which issimilar to the new EN 15632.DECREASING INSTALLATION COSTSThe most obvious advantage is the chance to reducethe installation time with flexible systems supplied incoil lengths of 100m and more. Compared to rigidsystems the following relative costs have been realizedin actual projectsAlthough material cost for plastic pipes are higherespecially for larger dimensions, the total installedsystem costs are lower, especially when using doublepipe systems wherever possible (see Photo nr. 5).BRANCH SOLUTIONSUntil now 2 types of branch solutions have been used.On site welded solution with Half-shells plus insulationto cover (see Photo no.:4). This technology has beenused for smaller networks. Due to homogenouswelding techniques, either with polyfusion or withelectrofuction fittings, the branches are corrosion freeand offer the same inner diameter as the pipes.Table 1Pre-insulatedsteel pipesFLEXALENMaterial costs 100% 90–150%Installation time 100% 20–25%Trenching 100% 50–70%Total 100% 60–85%Material costs are depending on the dimensioning ofthe system in the first place. In case of optimization ofpipe sizes and lengths according to the advantages ofPB pipes and connection systems, as described lateron, the material costs can be reduced for Flexalen.Installation costs are proven in practical experiencessince almost 30 years. Flexalen systems can beinstalled 5 times faster than rigid systems.Lower costs in trenching is related to the fact thatFlexalen systems are supplied in double line systems262Photo no.: 5 Polyfusion welded Flexalen branchPre-insulated Tees are another way to secure morereliable network quality due the reduced number ofjoints to be made on site (see Photo no.: 6). Thestraight connections are insulated with special kits witha robust slide over HDPE tube, which is sealed to theouter casing with heat shrinks.