The first is the problem of anti-corrosion of the outer wall. The quality of the anti-corrosion of the outer wall directly affects the service life. At present, the outer wall anti-corrosion of domestic steel pipes is mainly concealed. The steel pipes are required to be reinforced or specially reinforced outer wall anti-corrosion, and some areas promote cathodic protection. Common external wall anti-corrosion methods include coatings such as petroleum asphalt and epoxy coal tar pitch. The latter is not easy to cure at low temperatures, and there are many problems in the construction of welding joints on the site. In the past, chlorosulfonated polyethylene was used because of the large amount of solvent. It is easy to produce pinholes and is not suitable for breakdown. Some areas are no longer used. The anti-corrosion effect of cathodic protection is better, but the method of sacrificing the anode is adopted, and the anode must be replaced regularly in the future operation, which increases the running cost and operation.

There are three common methods for treating the inner wall of seamless steel tubes: anti-corrosion coatings, resin mortars, and cement mortars. However, there are two problems in the three methods: one is the bond strength between the anti-corrosion layer and the steel pipe. Both the anti-corrosion coating and the resin mortar require that the inner and outer walls of the steel pipe be thoroughly descaled to be constructed, but this is difficult to achieve.