Structure Brief Introduction

Anti-corrosion layer crucial point for steel pipe underground is for the life. For same material steel pipe, some over 40 or 50 years not corrosion, but some several years begin to leakage. These because used different anti-corrosion layers 

Its full name called extruding plastic polyethylene protection layer. The structure contains three layers. The first layer is for fusion bonded epoxy about 120um), the second layer is for adhesive (170-250um), the third outer layer is polyethylene (about 2mm) the protection layer thickness is over 2.2-2.9mm

Among these three layers structure, epoxy layer function is forming continuous coating, direct bond with steel pipe surface and features in resistance to chemical corrosion and resistance to cathodic disbanding, then happen chemical reaction with second layer adhesive active group to form chemical bond. It ensures that the anti-corrosion layer features in excellent bond property under high temperature.

The second layer usually is copolymer blinder, the main material is polyolefin. At present, it widely used as Vinyl copolymer adhesive. Copolymer adhesive polar parts of functional groups happens chemical reaction with first epoxy layer to form Hydrogen bond, chemical bond, it makes the second layer good bond with first epoxy layer, and non polar ethylene part happens reaction with third outer PE layer to make a good affinity. So the second layer also has excellent bond property with outer PE layer.   

Three layers structure polyethylene anti-corrosion layers composite epoxy coating and extrusion PE coating two kinds of excellent property. Epoxy coating feature and chemical resistance property composite that improve separate property, so it’s excellent for underground steel pipe as the protection layer.

According to the related material, 3 layers PE anti-corrosion layer can make the steel pipe underground life long 50 years. At present, in the international field, it is also considered as the most advanced technology. In China, 3layers PE has firstly used in oil, gas pipeline system.

In China, we have built Shangxi and Beijing gas and oil pipeline, and China crucial project gas transportation West-east nearly 4000km pipeline averagely used 3PE layers anti-corrosion.

In Tianjin city, Shanxi gas to here 67km high pressure pipeline, the outer ring line 30km high pressure gas pipeline, and underground gas pipeline 122km also adopted 3PE anti-corrosion. It has been the developing direction for the steel pipe anti-corrosion.

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