The three processes of electrochemical corrosion of
ASTM A179 cold drawn seamless pipe are as follows:
First of all, for urban gas system, because of the dense underground pipe network, the external power supply cathodic protection will interfere with other cold drawn steel tubes, which will cause their own interests and affect their family status. However, the use of the sacrificial anode protection method for the use of the cold drawn steel pipe than the negative metal and the cold drawn steel pipe does not appear. Therefore, the urban gas pipeline should adopt the antirust coating and the sacrificial anode combination.
Two, at present, there are mainly three kinds of PE composite structures, including three kinds of composite structures, epoxy resin powder (FBE), coal tar enamel, epoxy coal tar pitch and PE adhesive tape. Three layer PE composite structure, epoxy resin powder coating performance is good, so Europe and the United States is the main rust proof coating of cold drawn steel pipe. In China, considering the comprehensive economic considerations such as durability and maintenance cost, three layers of PE composite rust protection coatings are generally selected.
Third, in the sacrificial anode protection method, magnesium alloy is usually used as sacrificial anode to protect the cold drawn steel tube. Due to the destruction of output current, the design life of sacrificial anode of magnesium alloy is best matched with the service life of cold drawn steel tube, which neither wastes nor increases maintenance cost. However, it should be noted that sacrificial anode protection should not be used when the soil resistivity is too high and the protected cold drawn steel pipe passes through the water.
Four, different rust prevention methods have different quality and cost of rust prevention, according to the protection of the cold drawn steel pipe under different pressure, different use and different environment and different gas transmission conditions, the method of rust prevention and the cost of rust prevention should be considered comprehensively and comprehensively. When considering economic rationality, two points should be paid attention to: 1. Gas pipeline network construction, a rust prevention investment, 2. Since the city gas pipeline network is located in the city, the cost of maintenance is high and the cost is high after being put into use. It should be put into a proper increase in order to reduce the daily maintenance of the maintenance work of the cold drawn steel pipe.
