New Methods of Rust Removal

The inner and outer walls steel pipe deruster is used for cleaning the inner and outer pipe walls comprehensively through shot blasting. And removing the surface oxide skin by shot blasting. With high-speed flow from the strong and effective shot blasting machine, the descaler polishes the external and internal surface of rotating workpieces, removing adhering sand, rusty scale, welding slag, as well as oxide skin and its inclusions. As a result, a delicate smooth surface appears, promoting adhesion of lacquer and steel surface and fatigue & corrosion resistance, internal quality of the steel, as well as prolonging longer service life. 
The shot blaster is the unit curve blade that is installed with DISA technology preciously, including parts like blade wheel, main shaft, main bearing holder, cover shell, impeller, motor and bearing, etc. Structured by units, the machine has bullets with great inflow performance and unit power. In addition, it has proper structure and layout with impeller closed to the spindle end, which is very easy to maintain.    
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1.Cleaning Processe of the workpiece 
Charging Shelf → Feeding Mechanism→ Moving into the Shot Blasting Room→ Shot Blasting Treatment (the Workpiece Moves forward with Rotation) → Moving from the Shot Blasting Room →the Blanking Structure → the Blanking Bracket

2.Ball Circulation Process
Ball Storage → Flow Control → the Workpiece with Shot Blasting → the Bucket Elevator Vertically Shift → Separation of Shot and Slug →( Recycling ) Shot Blasting Machine

Tools for Rust Removal 
Using tools like steel wire brush to polish the steer surface, removing loose or tilted oxide skin, rust, as well as welding slag. Further more, rust removal can reach Sa2 level by manual operation, and level Sa3 by motor tool.  
 
Rust Removal Classification
The construction technology of anti-corrosion coating for steel pipe, which includes epoxy, vinyl, and phenolics. The level of steel pipe surface is required to be near white( Sa2.5). According to the practical experience, all oxide skin, rust and the others could be removed by level Sa2.5 with profile depth from 40μm to 100μm, which totally meets the requirement of the steel adhesion and corrosion layer. While the blaster technology could almost meet the technology requirement of level white( Sa2.5) with lower operation consumption and steady quality.     

Abrasive Blasting 
In order to achieve the ideal anti-corrosion performance, it is necessary to choose abrasive based on the hardness of steal pipe surface, level of original corrosion, required surface roughness and the coating type. As for the single-layer epoxy and two or three polyethylene coating, it would be better to use the mixture abrasive of steel sand and steel shot. Steel shot could strengthen the surface of steel while steel sand has ability to etch it. The mixture of steel sand and steel shot abrasive(usually, the hardness of the steel shot is from 40HRC to 50HRC, and steel sand is from 50HRC to 60HRC. Both of them are workable for steel surface, even good for the steel surface of level C and D. In general, there are two methods of the picking removal, the chemical one and the electrolytic one which is the chemical and the electrolytic. The tube anti-corrosion uses the chemical one only, removing oxide skin, as well as rust and the old coating. Further more, it could be used for the re-treatment after blasting sometimes. Although using the chemical one can make the surface clean and rough in a certain extent, it has quite shallow anchor pattern and might pollute the environment.

Spray Removal
We can not only completely remove the rust, oxide and dirt, but also achieve the even roughness that we require by the impact and friction of the abrasive. Spray removal can not only expand the physical absorption on the pipe surface, but also enhance the mechanical adhesion for erosion resistant coating and pipe surface.

Particle and Ratio of abrasive 
Small roughness can cause the decline of the adhesion and impact resistance of the erosion resistant coating. For serious internal pitting, we can not just use the big particle abrasive to impact with high strength, but also use the small particle to grind corrosive in order to cleaning. At the same time, proper proportion would ease the hurt given both the pipe and nozzle(blades), while there is going to have a promotion of the usage of abrasives. Usually, the particle size of the steel shot is from 0.8mm to 1.3mm, the steel sand is from 0.2mm to 1.0mm. Among which the size from 0.5mm to 1.0mm is the most. In order to gain better uniform cleanliness and roughness distribution, the particle size and ratio design of the abrasive are quite important. Rough surface could easily make the depth of the anti-corrosion layer profile thin, and severe deep profile could easily cause bubbles in anticorrosive coating during corrosion process, which had a seriously influence on the performance of the anticorrosive coating.
 

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