Multilayer composite pipes (MLCP) of metal and plastic were developed in the early nineties in Finland. Within ten years, the invention had completely changed the entire European market and now is the preferred product for plumbing, heating, and mechanical services and has the greatest market share in many parts of the world.
MLC pipes consist of two layers of plastic with an aluminum layer in the middle. Up to 40mm, the pipe is termed a rigid-flexible pipe. It can be bent by hand or with tools and it retains the shape. This makes it ideal for flexible installations and uses fewer elbows than rigid systems. Plastic normally doesn’t suit temperature due to the expansion, but the aluminum layer limits this as well as increasing the strength of the pipe. The pipes are complete with a fittings system, most of which are press-fit brass or plastic fittings.
MLC pipe systems have been in NZ since around the year 2000. One of the major brands is Multitubo which is made in Germany and has been distributed by Central Heating New Zealand since 2006. As it is a higher specification than the incumbent polybutylene plumbing systems it has been mainly used in warm water central heating systems. However, due to the range of dimensions available and the pre-insulation of pipe coils, it is becoming the system of choice for high-quality plumbing in commercial and residential and for mechanical services of both hot and chilled water. Other uses are in marine applications, compressed air, and industrial processes.
Multitubo piping system has been appraised for use by BRANZ; the multi-layer composite pipe is formed longitudinally overlapped welded aluminum with inner and outer layers of polyethylene raised temperature (PE-RT), tightly bonded to the aluminum with adhesive to form a pipe. Due to its higher specification and the strong flexibility Multitubo Pipe comes with a 25-year warranty.
- The multi-layer provides low weight.
- The composite pipe is oxygen tight, which prevents any oxygen diffusion through the pipe wall into the closed heating system.
- Multitubo pipe is corrosion-resistant because of high chemical resistance.
- The maximum working pressure and temperature for the Multitubo Piping System for the 16, 20, 25, 35mm pipes is 1 MPa at 70°C.
- The maximum working pressure and temperature for the Multitubo Piping System for 40, 50, and 63mm is 600 kPa at 70°C.
- The maximum continuous operating temperature of 70°C for potable water and 80°C for heating.