Analysis of corrosion factors and maintenance methods of steel molds

Overview:

Tetrapod is a general name for the seaside surface protection block. According to different shapes can be divided into accropodes, dolosse, hollow squares, tetrapods and other forms. Usually they are placed in the breakwater, shore protection, sand barrage, diversion dike and other seaport hydraulic engineering of the outermost, by weakening the impact of the waves to protect the dike and the inner circle of buildings.

In order to effectively reduce transportation costs and unnecessary losses, it is usually chosen to set up a prefabrication site close to the construction site, and to pour and produce wave dissipation blocks on site. And the wave block steel mold, the current market in China usually choose Q235 steel plate as raw materials, according to the actual needs of different projects, through the shear welding, the steel plate into the required template.

Analysis of factors affecting the corrosion of steel mold:

1. Chloride ion corrosion (commonly known as salt)

   As the application scene is mostly in the seaside, so the prefabrication site is also usually chosen in the seaside, because the marine environment is a highly corrosive, the air in the coastal area contains more sodium chloride and other salts, and the chlorine ions in the sodium chloride have the characteristics of small ionic radius, strong penetrating ability, and can be adsorbed by the metal surface more strongly. The higher the concentration of chloride ions, the stronger the conductivity of the aqueous solution, the chloride ions are easy to reach the metal surface, accelerating the process of localized corrosion. In the corrosion process, chloride ions are not only enriched in the pitting pit, but also enriched in the area where the pitting pit is not produced, and in some areas, the chloride ions will accumulate and nucleate, resulting in accelerated anodic dissolution in the area. In this way, the metal substrate will be corroded by the downward deep excavation, forming a pitting pit anode metal dissolution.

2. Air humidity

   The ocean is a giant reservoir, which in turn increases the humidity within the nearby environment, which creates sea air unique to the marine environment. Sea air blowing towards the ground carries more moisture and is more humid than wind blowing from inland. The moisture in the sea air can react with metals in an oxidizing manner, forming some tiny and thin liquid films on the surface of steel. The temperature difference of the sea surface varies greatly in summer. By the sunshine, temperature, evaporation and other reasons, the humidity in the air at this time is larger compared with the general wind or other times of the sea breeze, so the rusting force on the steel mold is greater. 

   Salt and alkali carried in the sea breeze also become higher when the temperature changes, and these salts and alkali increase the conductivity of these liquid films, thus accelerating the process of iron atoms losing electrons into iron ions. Therefore, the moisture and salt contained in the offshore air is the "real culprit" that eats up the metal.

Maintenance:

1.  Apply anti-rust paint

   Apply antirust paint can be directly from the physical surface to protect the steel mold, and the specific way of applying is divided into two kinds - steel mold outside the coating protection: wave block steel mold in the production of the factory must ensure that the surface of the steel plate without rust spots, such as rust spots must be cleaned up, and then coated with a layer of antirust paint to the steel mold, paint need to choose the anti-seawater corrosion resistance of sea breeze strong paint, and to ensure the corrosion resistance of sea water. 

   The paint should be selected the paint with strong corrosion resistance against sea breeze and sea water, and ensure the thickness of the paint is enough to provide effective protection. The inner side of the steel mold can be coated with protective oil during the idle period, and supplemented by other measures to effectively delay the inner side of the rust and corrosion.

2. Avoid open storage

   In order to avoid the steel mold due to sun, wind, rain and thus lead to the steel mold surface of the antirust paint coating damage, breakage, so that the steel directly with salt, humid air contact to accelerate oxidation and corrosion, as far as possible, do not store the steel mold directly in the open air, so the best storage method is to be placed in a dry, constant temperature, ventilated warehouses; when the conditions do not allow it is necessary to take other effective protective measures to be protected or to slow down the corrosion.

3. Regular maintenance

   During the storage period, the steel mold custodian should regularly check the condition of the steel mold, and find that there are corrosion parts in time to remove rust, add protective paint. To check the warehouse and so on whether there is no rain leakage or damage and other phenomena.