Introduction:

 Aluminum-plastic composite pipe (PAP) is a kind of pipe with a five-layer structure. The inner layer and the outer layer are made of polyethylene, the middle layer is welded with aluminum tube, and the aluminum layer is integrated with the inner and outer plastic layers through polyglue. Compared with the traditional galvanized steel pipe, PAP pipe combines the advantages of plastic and metal. As a composite pipe, it has the advantages of corrosion resistance, long life, bending without rebound, easy installation, so in early 90s of the last century, PAP pipe began to replace galvanized steel pipes for the construction of plumping system pipes.

The main advantages of PAP for indoor gas are:

(1) Zero gas transmission rate and high safety factor

Due to its unique five-layer structure, the PAP pipe has zero gas transmission.

(2) Welding with 0.6 MPa compressed air

PAP pipe has two types: overlap-welding and butt welding according to the welding method of the aluminum pipe.

Overlap-welded PAP pipe, aluminum ribbons are overlap-welded and form a tube, then pass through the co-extrusion die of extruder, and the co-extrusion die simultaneously extrudes polyglue and polyethylene in the inner layer of the aluminum tube. Since the plastic is just extruded from the die, compressed air is needed to make the plastic contact closely to the aluminum tube’s inner wall. In this process, we added the compressed air pressure to 0.6 MPa. Once there is a fake weld or missing weld, the overlap will burst open, the compressed air in the tube can play an online detection role. Therefore, the application of overlap welding PAP pipe in gas is safer than butt welded one.

(3) Limited joints, easy installation

The connection of the PAP pipe adopts the press-type connection, easy operation and reliable. It is easy to bend and does not bounce back. There are limited joints and the probability of leakage is low.

Conclusion:

(1) Compared with traditional galvanized steel pipe, PAP pipe combines the advantages of plastic and metal as a composite pipe, and has the advantages of corrosion resistance, long life, easy installation, and the application in gas will be more and more extensive.

(2) Through the testing and calculation of environmental temperature, reliability of connection and sealing, bending without rebound, stress bearing and heat compensation, the outdoor centralized wall-mounting method is adopted. The safety of the application of PAP pipe in PVC casing is fairly high.