Influence of asphalt on cathodic protection

In the construction of large storage tanks, we always need to lay a layer of green sand under the tank bottom plate to prevent the groundwater from flooding, so as to achieve the purpose of slowing down the corrosion of tank floor.

However, it has been proved that due to the change of the tank level and the deformation of the tank bottom plate, the asphalt sand layer will soon crack and pulverize, which can not achieve the purpose of autonomous groundwater. On the other hand, due to the temperature change, the moisture will enter the gap between the tank floor and the asphalt sand, and the water will be analyzed and condensed, causing the corrosion of the tank floor.

For the tank installed with cathodic protection, the existence of asphalt sand hinders the flow of cathodic protection current and affects the cathodic protection effect of tank bottom plate.

Coal tar epoxy coating is composed of epoxy resin, coal tar pitch, curing agent and filler. The coating was developed in 1955 and is mainly used for underwater pipelines and metal structures. The coating is resistant to mineral oil and chemical agents. The film is not only wear-resistant, but also has good adhesion to metal surface.

The cold coating process of epoxy coal tar pitch has great advantages over the hot coating of petroleum asphalt and coal tar pitch, especially for urban pipelines, which reduces the air pollution in the city. At present, it is widely used in urban water supply, gas and hydraulic gate in China, and also in oil and gas pipeline.

However, the epoxy coal tar pitch also has its own shortcomings, such as high requirements for construction conditions, sand blasting and rust removal on the surface, requirements for temperature and humidity, long curing time and large construction site. Due to the volatilization of solvent, the pinhole rate is high.

Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services.

Tel: +86 17568010262，0539-3712117.