in the water and electricity renovation or pipe network laying, many people will encounter such problems - there are PPC water pipes and PE pipes in their hands, want to connect them together, can they work? In fact, the answer is not a simple "yes" or "no", it has to be combined with pipe characteristics and connection methods to analyze in detail.

First talk about the basic characteristics of PPC and PE pipes. PPC water pipes are made of polypropylene copolymer, which has good toughness and impact resistance. They are often used for home improvement water supply or small projects; PE pipes are made of polyethylene, which is corrosion-resistant and flexible. They are more used in municipal pipe networks or outdoor drainage. Although both are plastic pipes, there are obvious differences in molecular structure and physical properties: for example, the coefficient of thermal expansion, PPC is about 1810 ^ -5/℃, PE is about 1710 ^ -5/℃, seemingly close, but under long-term temperature changes, the interface may still appear due to uneven expansion and contraction gaps; more importantly, the melting point - the melting point of PPC is about 150-160 ℃, PE is 120-130 ℃, which directly affects the feasibility of hot melt connection.

Many people's first reaction is "hot melt for plastic pipes", but direct hot melt of PPC and PE is not feasible. If the PE pipe is melted with the hot melt temperature of PPC (150-160 ° C), the PE will be overheated, the surface will be charred, the molecular chain will be broken, and the connection surface will become fragile; if the PPC is melted with the temperature of PE (120-130 ° C), the PPC will not be completely melted, the connection surface will not fit tightly, and there will be water leakage over time.

How to connect it? The answer is to use a transition joint. The most common is a dedicated PPC-PE transition pipe fitting, or a threaded metal joint (such as a copper joint): one end is connected to the PPC pipe with the hot melt temperature of the PPC, and the other end is connected to the PE pipe with the hot melt temperature of the PE pipe, or tightened by thread (such as the PPC pipe end is welded with an internal threaded joint, the PE pipe end is welded with an external threaded joint, and then the two are screwed together). This method can perfectly solve the difference in material and melting point, and is currently the most reliable connection method.

Of course, there are several precautions that cannot be ignored when connecting: First, the transition joint must be selected in line with national standards (such as GB/T 18742 "polypropylene piping system for hot and cold water"), and do not buy inferior plastic joints cheaply, which are easy to age and crack; secondly, the pipe end must be cleaned up - use scissors to cut the pipe end flat and wipe the burrs and dust clean, otherwise the impurities will get stuck on the connection surface and affect the sealing; finally, stress testing must be done after the connection is completed: use 1.5 times the working pressure (for example, household water supply is usually 0.6MPa, use 0.9MPa) to test for 20-30 minutes, no water leakage, no pressure drop is qualified.

To sum up: PPC water pipes can be connected to PE pipes, but they must not be directly melted! Transition joints must be used and installed in strict accordance with specifications. If you are inexperienced, it is best to find a professional water and electricity master to do it, or consult the technical staff of the pipe manufacturer first - after all, water pipe leakage is no trivial matter, once buried in the wall or underground, the maintenance cost is too high.