The outer galvanized and inner plastic coated steel pipes of seamless steel pipes are the same as plastic coated steel pipes, which are based on steel pipes. Should be coated inside and outside. Generally, the inner coating is plastic for anticorrosion, the outer coating used for plastic or galvanized layer or other coating materials can be selected according to the needs of users.

Therefore, the seamless steel pipe with galvanized outside and plastic coated inside should be surface pretreated for the base pipe first. The specific treatment steps are as follows:

1. Before shot blasting, the seamless steel pipe should be preheated to remove moisture, and the preheating temperature is 40℃～60℃;

2. The rust removal should reach the Sa2.5 level in GB/T8923, and the depth of the anchor pattern on the surface of the seamless steel pipe is 40μm～100μm;

3. The rust and dust remaining on the surface of seamless steel pipes should be cleaned up;

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

The above is the surface pretreatment method of seamless steel pipe.

Changsha Xiangjia Metal Materical Co., Ltd. the Steel Pipe Division of ADTO GROUP, is one of the leading manufacturers of steel products in China. We specializes in manufacturing all kinds of steel pipe in various grades and sizes. Years of production experience and manufacturing facilities who have a capacity of 200,000 tons per annual will ensure the good quality and competitive duration of our products.