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, EstoniaProduction of PB service pipesAll service pipes are made of Poly-butene. This is aplastic with a special combination of properties. Polybutenehas excellent heat and creep resistance,flexibility and strength at a long lifespan and is fullyrecyclable. In accordance with the temperatureduration profile mentioned in the BRL5609/EN15632,PB is suitable up to a maximum temperature of 95 °C.All PB-pipes are weldable by socket fusion, electrofusion and butt welding, which allows for an all plasticdistribution system without metal parts that are prone tocorrosion. The service pipes are produced via state-oftheart extruders.The production line consists roughly of an extruder,calibration tools for adjusting pipe size, cooling baths,and marking and cutting equipment.Pipe dimensions are checked inline every secondduring and after production with ultrasonicmeasurements. PB-pipes can be produced up to anouter diameter of 225 mm.If desired an outer oxygen barrier layer may be appliedvia co-extrusion up to an outer PB pipe diameter of 90mm.After production the PB-pipes are stored for a minimumperiod of 5 days and cured to create the correctcrystalline polymer structure. After curing the pipe isused for the Flexalen 600 production.Every batch produced is verified by the in-house QCdepartment according to Dutch directives- BRL-K5609, for PB pipes with oxygen barrier or- BRL-K17401 for PB pipes without oxygen barrier.Product and manufacturing processes are checked 6-8times a year and certified by independent agenciessuch as Bureau Veritas, KIWA and CSTB and leCentre Scientifique et Technique du Bâtiment. Thequality of the QC department is validated by thesechecks and by internal and external audits.Production of LDPE insulation foamThermaflex has now approximately 35 years ofexperience in the production of LDPE foam viaextrusion techniques.Most of the raw materials that are used are tailor-mademixtures according to Thermaflex specifications.Through these specifications and proper productionquality control the company‘s philosophy related tocore business is also realized for raw materials.During the heating, melting and mixing of the rawmaterials the foaming agent is injected into theextruder. This foaming agent is a hydrocarbon thatcauses the expansion of the LDPE.The quality of the foam, moreover the insulationproperties of the foam, depends on parameters such asdensity, cell size and chemical composition. Allparameters are measured and adjusted within limitedtolerances to meet the specifications. The bestefficiency is further improved when the space betweenthe service pipe and the foam is filled better.As there is no bonding between the service pipe andfoam, there is no risk of damaging the foam andproperties by expansion of the pipes due to thermalfluctuations in the applications.Production of corrugated outer casing (HDPE) andassembly of complete productThe outer casing is applied by an extrusion processand thermally welded to the foam after the pipe hasbeen inserted. The outer casing is also corrugated tooptimize the flexibility of the finished product. Now theproduct is ready for coiling.After production the final product must cure for 5 days.During this curing period the degassing of the foamingagent starts, while the insulation foam is still stabilizingProduction testing and controllingDuring the production, parameters are checked andcontrolled, such as:1 Chemical composition of the foam.2 Settings of all extruders involved (foam extruder andextruder for corrugated outer casing).3 Density and cell size of the foam.4 Dimensions of the foam (outer diameter and innerdiameter).5 Line-speed of all involved products (Foam / PB-pipe/ End-product).6 Thickness of the corrugated outer casing and theconnection of the corrugated outer casing to thefoam.7 Since a few months: in-line production control ofHeat Loss of the pre-insulated pipe system.The most prominent factors to influence heat loss areparameters one to four. The foam lambda is directlyaffected by these factors as represented in equation 1. total convection conduction radiation blowingagent(1)114