pex-al-pex pipe is a new and environmental friendly product without secondary pollution which is popular in the 21st century. it is convenient to install with less joints and better effects than metal pipes and not easy to rebound.this bonding will prevent leakages and rust that normally occur with press fittings and screw fittings. they are clean, toxin free, corrosion resistant, odorless,light weight,high mechanical strength, heat resistant and able to prevent encrustation. it has a lifespan od fifty years or more as comfirmed by the international government. pap conposite pipes consist of a core aluminum with inner and outer layers of plastic,tightly bonded to the aluminium by means of a special adhesive. pap has not only high pressure resistance like the metal pipe but also more new advantages. 1).compared with the metal pipe, pap composite pipes has the same strength, easy to bend, reluctant to retain former shape. 2).super propertise of high teperature, high pressure and corrosin resistance. 3).smooth inner surface of the pipe reduces resistance to the fluids. the ability to conduct water is 30% more efficient. 4).fire resistant property 5). good property of heat preservation, heat conduction coefficient is 0.45w/m.k, which is much less than metal pipes and it can save insulation materials outside the pipe. 6). ease to cut and install. 7). lifespan of the pipe is more than fifty years. 8). light weight, the weight is 1/10 of galvanized pipes and lower transportation fees and lower cost are reduced. 9). the pipe can be used as reck piping and underground piping and easily located with a metal detector. 10). the core aluminum pipe can prevent oxygen seepage to avoid the bacteria.