Anticorrosion method for inner and outer walls of steel pipes
Light steel pipe raw materials, high strength, good tolerance, can withstand high internal pressure, sensitive production and application, can be used in messy or harsh geological conditions. However, there are drawbacks in the use process, mainly the internal and external anticorrosion treatment is more troublesome.
1. First of all, the exterior wall anticorrosion problem. External wall anticorrosion quality directly affects the service life.
At present, the exterior wall anticorrosion of steel pipe is mainly concealed. All steel pipes need to be reinforced or specially reinforced, and cathodic protection is being promoted in some areas.
The common anti-corrosion methods for external walls include petroleum asphalt, epoxy coal asphalt and other coatings, which are not easy to cure at low temperature. There are many problems in the construction of on-site welding joints. In the past, chlorosulfonated polyethylene was used, due to the large amount of solvent, easy to produce pinholes, unable to resist penetration, some areas have been used.
Cathodic protection has good anti-corrosion effect, but because of the method of sacrificing the anode, the anode must be replaced regularly in the future operation, which increases the operating cost and operating expenses.
2. There are three commonly used treatment methods for the inner wall of the steel pipe: anticorrosive coating, resin mortar, cement mortar.
But there are two problems in these three methods: one is the bonding strength between the anticorrosive layer and the steel pipe. Both the anticorrosive coating and resin mortar require the inner and outer walls of the steel pipe to be cleaned thoroughly before construction, but this is difficult to achieve. So rust spots are the source of subsequent stratification, constituting corrosion and scaling. Second, most steel pipes are butt welded on the spot, after welding anti-corrosion. Only manual, quality control is not good. For pipelines with small diameter, personnel can not enter the construction and anti-corrosion treatment can not be carried out, which also forms a hidden danger of weld damage in the future.
