Introduction of the material of the axial fan oil pipe

The oil level in the reduction box of the axial flow fan is externally displayed on the level gauge outside the air cylinder through the oil pipe at the bottom of the reduction box. SL98 fan oil pipe material is made of galvanized carbon steel pipe. Corrosion holes with a diameter of about 5mm are found at the bottom of the oil pipe at 600mm from the reduction gearbox. The amount of oil leaked per unit time is not much, plus a large amount of water vapor in the air cylinder, so there is no oil layer accumulation on the surface of the water collector below the leak point.

The system uses boron bromide solution as a daily biocide. Due to the addition of biocide and the action of fan pulling, the water vapor in the cooling tower fan often contains bromide ions. Carbon steel that has not taken anti-corrosion measures is prone to pitting under the action of halogen ions, and the holes produced by pitting are mostly small, usually covered by corrosion products or deposits, so it is difficult to find pitting .

The water vapor entrained with bromide ions rises under the action of the fan, and attaches to the bottom of the outer oil pipe of the SL98 fan base, causing pitting on the surface. Due to the covering of the corrosives, it has not attracted attention in the routine inspection of the fan, which eventually led to perforation happened.