1. Before shot peening, 304 stainless steel pipe shall be preheated to remove moisture, and the preheating temperature shall be 40 ℃ ~ 60 ℃;

2. Derusting shall reach grade Sa2.5 in GB / t8923 rust grades and derusting grades of steel surfaces before coating, and the depth of anchor grain on the surface of 304 stainless steel pipe shall be 40 μ m～100 μ m;

3. The residual rust dust on the surface of 304 stainless steel pipe shall be removed;

4. Spraying shall be carried out within 4h after surface pretreatment.

In addition, the surface galvanizing methods of 304 stainless steel pipe mainly include hot galvanizing and electro galvanizing. Hot galvanizing includes wet method, dry method, lead-zinc method, oxidation-reduction method, etc.

The main difference between different methods of hot dip galvanizing and ground galvanizing is what method is used to activate the surface of 304 stainless steel pipe and improve the quality of galvanizing. At present, dry process and redox process are mainly used in production.

The surface of the zinc layer is very smooth, dense and uniform; Good mechanical properties and corrosion resistance; The zinc consumption is 60% ~ 75% lower than that of hot dip galvanizing. Electro galvanizing is technically complex, but this method must be used for single-sided coating, double-sided coating with different coating thickness on internal and external surfaces, and galvanizing 304 stainless steel pipes.