The blackening of valve block is also called bluing, which is a surface treatment process that the workpiece forms a layer of blue or black oxide film on the surface of the workpiece at room temperature or heated to an appropriate temperature in air, steam or chemical solution to improve its corrosion resistance and appearance.

Hydraulic valve block (referred to as hydraulic valve) is the control element in the hydraulic system, which is used to control the pressure, flow and flow direction of the fluid in the hydraulic system, so as to meet the requirements of different actions of various executive elements.

Hydraulic valve block is a kind of automatic component operated by pressure oil. It is controlled by pressure oil of distributing valve. It is usually combined with electromagnetic distributing valve. It can be used for remote control of oil, gas and water pipeline system of hydropower station.

The design of hydraulic valve block mostly belongs to non-standard design, which needs targeted design according to different working conditions and use requirements. The design of valve block is roughly divided into the following steps: material selection, processing and heat treatment, deburring and cleaning, surface anti rust treatment and test.

According to the refrigeration mode of the station, the hydraulic valve block can be divided into: 1. 2. Forced refrigeration: forced refrigeration is carried out by refrigerator, which is generally used in the system with oil tank capacity greater than 250 L. The main technical parameters of the hydraulic station are the oil storage measurement of the oil tank and the motor power.