Detailed Product Description
Equipment list
The outside coating line for steel pipes consisted by:
a. Steel pipe support table & sanding system.
b. Surface rust remove conveyer.
c. Steel pipe preheating system.
d. Steel pipe rust removing machine (including dust ventilation unit, dust separator, powder filter and connection tubes etc.).
e. Middle platform
f. Rust remove inspection table.
g. Steel pipe inside blowing and cleaning unit.
h. Coating conveyer line.
i. Acid pickling equipment.
j. Medium frequency heating device.
k. Epoxy powder spray device.
l. PE extrusion machine.
m. Adhesive extrusion machine.
n. Raw material supply system.
o. Water cooling system.
p. Coating layer inspection table.
q. Pipe end facing machine.
r. Pipe taking out table.
s. Pipe transferring wheels.
t. All the Pneumatic, hydraulic and electrical control systems.
Production processing description:
Take the 3PE coating for instance:
The steel pipe goes to the rust remove conveyer by pipe transferring system. At the conveyer, pipe moving and tuning spirally through the medium frequency preheating and rust remove machine to take the rust removed. The preheating temperature is going up to 4060 at the surface of the pipe.
The preheated pipe moving and turning with setting speed into the rust remove machine and removing rust at the steel pipe surface by shot blasting head. The rust removal powders are collected for recycling system. The dust powder will be treated by powder treating unit.
After removing the rust, the pipes come to rust checking table and clean by blowing and cleaning device.
The cleaned pipe ends will be covered with paper to keep the ends without coating.
After the inspection the unqualified pipes will be send back to rust removing conveyer.
The qualified pipes will go from checking table to coating conveyer line. In case acid pickling needed, the pipes will be taken acid pickling, water washing and chrome painting on the line. Next, the pipe will go to medium frequency heater to make the temperature on pipe surface come to 180-220. Then the hot pipe go into epoxy spray room, the electrostatic spray gun in the room spraying the epoxy powder on the pipe surface and make the powder become a well distributed epoxy layer. That is the first layer of epoxy coating.
If the pipes need two layers of epoxy coating, another gun with one separately feeding system will spray another layer of epoxy powder, to get two layers of epoxy coating.
The pipe surface with epoxy powder having gelatinized and go to the parts of adhesive extrusion and PE extrusion machine. The raw materials of adhesive and PE melting and coming out under the certain temperature and pressure from the extruder through T die head as thin layer. First the adhesive layer is wrapped on the surface of the pipe and then the PE layer also be wiped. As the pipe moving towards spirally the adhesive layer and PE layer is wiped continually to make the pipe surface well coated.
After finish the PE coating, the pipe goes to water cooling part immediately getting cold to avoid any damage of the coating layers. Many rollers to be used to support the pipe in cooling part in reducing the pressure on the surface of the PE layer and keeping the thickness of the coating material on the welding part on the pipe. The cooling water will go to cooling tower getting cold and come back to be circulated.
Outside the cooling room, there is a spark leaking detector with a conducting rubber head. The rubber head will touch and take checking for the surface of the pipe while it moving as spiral way. When any leakage point is checked out the instrument will alarm automatically.
The coated pipe then go to the end of outer coating line and take the inspection for the coating layer on the checking table. The pipe also be removed the pipe end protection layer and cleaning. Finally the pipe will go to pipe transfer conveyer with marking.
