TPT January 2007

Technology Update

Benefits of plastic heating and plumbing pipe

The increase in copper prices is a principal motivation for stepping up plastic pipe manufacturing production. Global consumption of metal is on the rise, especially in China, India and Russia, with the price of metal increasing in 2006 to more than five times the price paid in 2001. Comparatively, polymer-based pipe alternatives are attractive. Maillefer, Switzerland, aims to assist manufacturers with a catalogue of complete extrusion line products covering the full range of PEX and PE-Al-PE composite pipes.

defect to what should be a perfectly round product. Composite pipe meeting these requirements is available from Maillefer’s PCL lines. Composite PE-Al-PE pipe is a five-layer construction, which uses aluminium sheet as the barrier layer sandwiched between two PE layers. The PCL line exists in versions for PEX-b and PEX-c crosslinking methods as well as for PE-RT. Adhesive layers serve to bond the aluminium to the PE. Various welding technologies are available, including TIG or laser welding. Maillefer’s production programme includes extrusion lines for pipes from 8mm (0.315") to 110mm (4.33") in diameter. PXL models for one, three and five-layer constructions are repeatedly delivered to the market. Commonly PEX-b crosslinking methods are employed, like the familiar one-step Monosil (with liquid silane injection), or the two-step Sioplas (pre-grafted PE silane compound). The PEX-c method, where crosslinking is initiated offline, is also available. fi Technology for the IR PEX-a method of crossinking

› Maillefer produces extrusion line products for PEX and PE-Al-PE composite pipes

Another alternative to crosslinked PE is heat resistant PE-RT. The multi-layer constructions call for EVOH to be used as an inner barrier layer together with an adhesive for layer bonding. The company has also industrialised its proprietary IR PEX-a method of crosslinking. In addition to the advantage of being a one- step method, it is also a one-step curing process. Instead of needing a separate hot bath or sauna step, the curing takes place during the extrusion process by means of infrared ovens placed between the head and the calibrating trough. Currently, IR PEX-a is offered in a single-layer version. Maillefer’s latest PXL 032-5S line is used for producing five-layer PEX pipe. Typical pipe constructions are composed of an inner PEX layer, adhesive, EVOH barrier, adhesive and an outer PEX layer. The new version ECH 10/45 ML head and tooling enhances layer distribution, both in terms of concentricity and uniform thickness across all five layers. The same crosshead is also configurable in three-layer and single-layer pipe constructions. Maillefer SA – Switzerland Fax : +41 21 691 2143 Email : info@maillefer.net Website : www.mailleferextrusion.com

› Five-layer pipe construction

In the safety-conscious United States, certain regions initially showed resistance to plastic pipe in general, due to confusion surrounding PEX and PVC pipe. Standards such as NSF/ANSI Standard 61 recognise PEX pipe as safe, and the specifications include tests for detecting potential contaminants in potable water distributed with PEX pipe. Heating and plumbing pipe is found in a variety of applications, including radiant heating and cooling, surface heating to melt ice and snow, hot and cold water distribution, and fire sprinkler systems. One noticeable trend is the use of small diameters, eg when PE-Al-PE pipe is fitted into 9.7mm ( 3 / 8 ") thick plywood sheets, over which finished flooring is placed. Such use of small diameters leads to a preference for butt-welded composite pipe versus the overlap method. When using overlap, the 3 / 8 " pipes show a flat side

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J ANUARY /F EBRUARY 2007