Production of a Multi-Layer Composite Pipe for Robbens Systems- Underfloor Heating

One of the most important parts of a warm water underfloor heating system is the pipe. Therefore, multi-layer composite pipes are found in more and more houses. Robbens Systems, one of the most experienced underfloor heating suppliers in the UK market, works with high quality multilayer-layer composite pipes by FRÄNKISCHE a leading European manufacturer of building and industrial pipes. As the name suggests, multi-layer composite pipes are made of several layers of different materials. But how do you produce multi-layer composite pipes? And how do you create a strong, permanent bond between aluminum and plastic?

Multi-layer composite pipes consist of five layers. The inside and outside layers are made of plastic tightly bonded, with special adhesive to the mid-layer of an aluminum core. Using the example of “alpex“ pipes manufactured by Fränkische Rohrwerke, we will explain the steps necessary to manufacture multi-layer composite pipes. FRÄNKISCHE produces high quality underfloor heating pipes for Robbens Systems who have been at the forefront of the UK underfloor heating market for over 15 years now.

The production of multi-layer composite pipes consists of five main stages. The real knowledge and know how is contained in numerous additional smaller steps. The raw material required for production is extensively scrutinized and tested before a single pipe is produced. Flawless raw materials are essential in starting multi-layer composite pipe production.

The extruder is the first stage in the production process. Plastic pellets are fed into the extruder. The melted plastic is then forced through a die to form the inner plastic pipe (inliner). Whilst still soft, the plastic extrusion is then passed through the vacuum calibration device and the cooling bath to cool and solidify. During the next stage, a second layer, the so-called adhesive layer, is applied to the inliner. This adhesive layer creates a strong, permanent bond between the aluminum pipe and the inner plastic pipe during the third stage. The aluminum strip is fed directly from the coil, applied and formed around the inliner and welded. At Fränkische Rohrwerke, they use the butt-welding technique. Butt welding means that the edges of the strip of aluminum are butted not overlapped, thus creating a butt joint. Because both pipes are cold at that point, the aluminum layer is heated to activate and cause the intermediate adhesive layer to permanently bond both layers together. Then another adhesive layer is applied to the intermediate product to bond the plastic outer layer to the aluminum in the fifth and final step. This will provide protection. After being pulled through another cooling bath and after all markings, such as quality certificate and DIN numbers, have been applied, the finished product is cut to length or coiled.

Advantages of the multi-layer composite pipe:

• Excellent sound absorption properties
• Optimum flow properties
• Corrosion resistant
• High chemical resistance
• Hygienic and toxic free
• Incrustation free
• 100% oxygen-tight

Robbens Systems – Underfloor Heating, is part of FRÄNKISCHE. Robbens Systems design and manufacture underfloor heating systems for all types of homes, and combine proven underfloor heating technology with the staff and service to make every project a resounding success. They offer systems for all floor construction methods and all floor finishes, including timber floors.

For further information, visit www.underfloorheating.co.uk or e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it or tel 01424 851111.