Piling pipe is also known as pipe, welded steel pipe made of steel sheet or strip after curl after forming divided into Longitudinal and spiral welded pipe; the welding process is divided into stove pipe, welded pipe and automatic arc welded pipe, pipe materials and for different purposes is divided into: galvanized welded steel pipe, stainless steel welded steel pipe; but also because of the shape of the end is divided into the tube, square tube, rectangular tube, oval tube, P-shaped tube. Special Pipes. Piling steel pipes used in billet steel sheet or strip, buried pipeline electrochemical corrosion process and its anti-corrosion methods start from the inhibition of one process. Plus anti-corrosion coating in the pipe wall, can increase the loop resistance, reduce corrosion current; plus DC power, so that the pipe on the soil caused by the negative potential, the formation of cathodic protection, and eliminate the anode and cathode potential difference to stop the anode and cathode process, fundamentally carried out. Anti-corrosion coating and the rule of law, cathodic protection of the rule of law in this. However, once the anti-corrosion coating is damaged, the exposed iron parts to accelerate localized corrosion. Therefore, anti-corrosion coating and cathodic protection of the combination is rid of this economical and effective. The United States and other countries have clearly defined, anti-corrosion coating and cathodic protection must be used. But for the city gas system, the underground pipe network-intensive, cathodic protection, plus the power of the other pipeline interference caused by their own benefit, the situation of his victims. Negative than the steel tube potential of metal materials and steel pipe connected to the sacrificial anode protection law does not appear such a situation, therefore, the gas trunk pipelines for City Gas combining anti-corrosion coating and sacrificial anode corrosion. Other low pressure trunk pipeline, the general anti-corrosion coating.
