TPT September 2009

T echnology U pdate

Non-stop production of foam insulated composite pipes for greater protection

THE use of composite pipes (PEX-Al- PEX) has grown to occupy an important segment in the heating and plumbing pipe industry. These pipes are available in different forms according to the installation conditions. Certain composite pipes require a protective outer construction, such as a flexible corrugated pipe or a foam tube. Composite pipe inserted in a flexible corrugated pipe is typically placed in cement foundations and inside walls. Aerial or free hanging composite pipes are fitted with a thick foam tube in order to enhance their insulation properties. Maillefer, Switzerland, provides complete systems for multilayer composite pipe manufacturing, and also delivers lines for producing flexible corru- gated or foam insulated composite pipes. For a line configuration that features non- stop, full-speed production of foam insulated composite pipe, typical specifications include entry foam tube lengths from 700 to 1,200m, entry foam tube diameter from 28 to 46mm, entry composite pipe diameter from 16 to 26mm, typical foam tube thickness of 6 or 10mm, maximum bar length of 6m and a maximum production speed of 35m/min.

The line functions are composed of five steps: pipe and foam payoff, foam tube application, seam welding, jacket extrusion and conditioning in bars or coils. Both the foam tube and the composite pipe are fed to the line using two single payoffs. To make continuous production possible, an accumulator is used when switching from the empty payoff to the full one. In parallel, the composite pipe is introduced from another pair of single payoffs. The pipe is either on coils or reels. Composite pipe diameters range from 16 to 26mm. The foam tube is applied around the pipe by first slicing it open lengthwise, then merging the pipe into the foam tube. The cut edges are then heated before being joined together to form a welded seam. A compression phase maintains the edges perfectly aligned and the foam tube is held in place as the weld solidifies. Finally the product is ready to receive its outer jacket. The foam insulated pipe enters the extrusion head where a medium/high density PE layer ranging from 0.15 to 0.2mm uniformly seals the foam tube. The MXC extruder, coupled with the most recent screw and barrel innovations, offers a linear and homogenous melt across the full RPM range. The nearly finished pipe then enters a section of cooling water trough before reaching the conditioning components of the line. The product is conditioned either as coils or bars. Coils are wound on the MWB 1300

 Merging the pipe into the foam tube

fully automatic dual coiler, which features continuous coiling and strapping with up to six straps. The pipe being coiled is cut at predetermined lengths by one of two saw types, radial or planetary. Both full cuts and partial circumferential cuts are possible. Straight bars are fully cut at predetermined lengths with the radial saw. The Nomos ® PSU line control ensures a precise synchronisation of the various line operations at the highest possible speeds for the product. Extruder control and line speed are optimised for high quality and minimum scrap. Advantages offered by composite pipe manufactured with a foam tube include a foam insulated pipe that is ready to use; a perfect alignment of cut edges for a round product; a complete weld throughout the full thickness of the foam tube; a fine weld seam that is barely noticeable; a smooth, continuous surface from end to end, without foam tube retraction and wrinkles; and a product that is sealed with a protective outer layer. Maillefer SA – Switzerland Fax : +41 21 691 2143 Email : info@maillefer.net Website : www.mailleferextrusion.com

 Cooling of the extruded jacket

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S eptember 2009

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