March 2006, “Milan MCE international sanitary ware expo” was held in Milan of Italy. Shanghai Akan New-style Building Material Co., Ltd., Shenyang Jinde Pipe Industry Group, Foshan Rifeng Enterprise Co., Ltd. attended this expo. In this expo, aluminum-plastic & steel-plastic static metal composite pipe----- al-winded PP-R pipe—unfamiliar with conventional metal composite pipe was spotlighted. In static al-winded PP-R pipe , PP-R interior layer and al-winded or plastic exterior layer formed five-layer structure protection jointed by hot-melt adhesive.
Unconventional polypropylene (PPR) pipe, crosslinked polyethylene(PEX) pipe, polybutene (PB) pipe, chlorinated polyvinyl chloride (CPVC) pipe and aluminum-plastic composite(PAP) pipe are applied in cool and hot water piping system conventionally, the previous four pipes are entirely-plastic pipe, the rest one is plastic composite pipe. ISO certification for PPR, PEX, PB and CPVC pipe are all stipulated with 50 years service life. China also stipulated relative standard.
This indicates that all plastic piping complied with the above standard must have 50 years service life under common work condition. But the above pipes also have disadvantages: by means of superior physical and chemical properties and high performance cost rate, PPR and PEX pipe are widely applied at home and abroad. But use range is limited caused by high online expansion coefficient and oxygen leakage. CPVC pipe is mainly applied in chemical and piping system with special requirements, such as fire-retardant due to disadvantages of processing, sanitation and expensive material. These four entire-plastic pipes are ease to be scratched. Plastic-aluminum composite pipe, devised for the purpose of improving linear expansion coefficient of entirely-plastic pipe and insulating oxygen. Additionally, plastic-aluminum composite piping system was utilized increasingly in recent years in European Market. But 50 years service life standard has not been stipulated by ISO. Our national standard GB/T18997-2003 applies some stipulations of ISO entirely-plastic pipe standard, such as 50 years service life, long-period static liquid intension. But this standard do not conform 50 years service life corresponding to technical requirements. Related experts indicated that the weakest part of plastic-aluminum composite pipe is adhesive medium between aluminum and plastic, but working condition of adhesive layer is hard to be tested in static hydraulic test, even long-period hydraulic test. Adhesive layer is a key factor to achieve structure integrity in plastic-aluminum composite pipe.
PPR pipe is the widest applied in China , but it can not be applied in exposed installation fields without oxygen-insulated condition. Static PPR pipe tackles problems of high linear expansion coefficient and oxygen leakage
The intensity of PPR static pipe is determined by interior layer principally, which means 50 years service life of PPR pipe is determined by intensity of interior layer, and aluminum layer and exterior plastic layer function low linear expansion coefficient and anti-oxidization with few contribution to intensity.
But the intensity of plastic-aluminum composite pipe is determined by interior layer, aluminum layer and exterior layer jointly. Mechanical property analysis is extremely complicated, which needs to analyze diverse invalidation modes, such as adhesive agent failed and temperature-changing factor of special materials. And corresponding supervision methods to these invalidation modes are also complicated technologically. At present, this difficulty can not be solved completely. Thanks to low linear expansion coefficient, anti oxygen-leakage and entire plastic, static PPR pipe features excellent light covering property, anti-static, anti-ultraviolet, thermal-fused joint. Used for hidden-buried spots, it has exploration, excellent anti shock and anti scratch, etc.
Static composite pipe is one of promising cool and hot water piping systems, which represents development direction of plastic cool and hot water pipes. Static aluminum-layer PPR pipe is widely applied in diverse fluid transport systems.
• Interior cool and hot water transport system, especially for unhidden pipe installation;
• Central air conditioner support piping system
• Integrated heating system
• Solar piping system
• Corrosive water supply, i.e chemical production zone,etc.
Over the past two years, some companies with strategically insight implement relative equipment and supporting applied technologies. It's reported that, Akan's static aluminum-layer PPR pipe was developed in second half of 2004. In recent two years, we have kept improving on it with matured production technology, complete accessory equipment, mature construction technique and scalization product. Our static aluminum-covered PPR pipe is applied in key projects in China and exported to over 20 countries and regions.