An Innovated Steel-Plastic Composite Corrugated Pipe For Sewage System Today in China along with wide application of composite pipe, various steel-plastic composite pipes have been developed. Here we would like to introduce a typical steel strip reinforced polyethylene spiral corrugated pipe (hereinafter called as MRP pipe), which has Chinese patent technology, economy in investment and suitable for our applications. It is a great technical innovation to use the steel-plastic composite construction instead of the single material (plastic). The new combined structure brings many advantages like higher stiffness, less weight, low cost, etc. Therefore the new pipe has showed its unique advantage and competition in market in a short time. More than 35 pipe production lines have been started up in China and some machines have been exported to Europe and Middle East already in the recently 2 years. However, it is not a perfect sewage pipe system yet, there are still some problems need to be solved either in theory research aspect or in practical application. From the diagram we know that the main pipe body of MRP is formed by the HDPE layer (inner and outer layer), and V-shape steel band which pre-coated with adhesive resin on the surface undertakes the primary support of the pipe; the steel and HDPE is wrapped on the mandrel and bond together to be one integrated spiral-corrugated pipe. Thereby, this new pipe collects advantages from different materials organically, high rigidity and strength of steel; anticorrosive, wear proof properties and flexible of plastics. Fig. 1 Structure of MRP spiral-corrugated pipe

The advantage of the MRP pipe 1) High ring stiffness For normal buried sewage plastic structure wall pipe, its maximum ring stiffness is difficult to over SN8. But in new pipe, stiffness can easily reach the surprisingly value of SN8, SN12.5 and SN16, even higher if necessary. In other hand, thanks to plastic properties, the plastic-steel-plastic composite structure could against corrosion very well. Therefore, this composite corrosive-proof pipe could be applied under different kinds of hard conditions. For example, at some coastal areas, due to the soil contains corrosive substance, the concrete...

The other process point is to protect the metal layer out of corrosion. In MRP pipe, the steel rib is completely covered with polyethylene, the liquid, air and soil cannot contact with the steel reinforcement, so it guarantee the anti-corrosive performance of the MRP pipe. This pipe system provides different connecting method to match the varied demand of credible sealing and convenient installation preferably. As well, the MRP pipe has many properties relative to other plastic drain pipe, such as reliable water sealing, long service life, flexible and earthquake-proof, less weight, easy and...

Process of MRP pipe production First, wrap a core PE solid wall tube on the main mandrel of the machine. Second, form the steel band into “V” shape and locate it into the designed position of the core pipe. And finally extrude an outer PE layer to cover the steel reinforcement. This bonding of steel to the polyethylene is finished in a short time and under a certain pressure, so all layers will be compounded into an integrated structure and be greater than the tensile of polyethylene resin. Conclusion Recently, the development of steel-plastic composite pipes has received a lot of supports from...