Pipe-feeding rack carries qualified pipes to external derusting production line, and on the derusting line, the end-to end connected pipes go ahead, and then go through the  preheating furnace for heating. When the temperature of pipe reaches to 40°C to 60°C, the pipe will satisfies the demands of blast cleaning, because the pipe surface moisture is dried at that time. 

After preheating, the end-to end connected pipes are transported through the blast cleaning machine. At that time, with he help of the machine, the oxide skin on the pipe external wall is cleaned, which can reach to the standard cleanness, as well as forming anchor pattern, in order to strengthen the adhesion stress between coating layers. 
After rust removal, steel pipes pass burner, acid -washing, water washing to complete the acid treatment on steel pipe surface, and then go out of blasting transmission line. Pipes will go through internal dust blowing, pipe end treatment (wrapping) and the unqualified pipes will go out of production line under the help of v-type transmission line to shot blast. While the qualified steel pipes enter into coating transmission line through the pipe coating incoming racks. 

And with the help of coating conveying line, and pipe connectorthe end-to-end connected pipes go ahead, and then go through the intermediate frequency which heats the pipe up to the required temperature (180-230°C). (When pipe surface doesn't go through chemical treatment, it needs to go through surface dust cleaning to remove dust on surface before intermediate frequency heating.)  

The waste pipes are also reprocessed here by a stripping unit. After intermediate frequency heating, the PE layer is softened and be stripped with special stripping device(knife system). And then the FBE LAYER and residual impurities on steel pipe surface will be brushed by brushing unit powered by a motor. Unit has its own sturdy steel frame and is lagged to cement floor by supplier.

After intermediate frequency heating, the pipe is transported to FBE coating room and AD&PE winding area, in order to finish three coating layers. 

Then, the coated pipe will be sent to water cooling area, and the temperature will drop immediately below 40-50°C, which will not only protect the coating layers, but also provide convenience for the next processes.

The function of the pipe-end polishingdevice is to remove the pipe-end coating layer, to achieve the standard code or the customer's demands, for the follow-up welding. After cut backing, the coated pipe enter to the inspection platform for automatic electric spark missing inspection and testing the coating layer thickness and appearance. 

The qualified pipes then go into marking station and be transported to storage place after certain protection.

The unqualified pipes will be returned to pipe-end polishing station to go through second treatment,