Zinc Spraying Machine

Process and Advantages of Zinc Spraying (Zinc Coating Thermal Spraying) on LPG Cylinder Surfaces:

This is a very important anti-corrosion process that significantly extends the cylinder's service life and ensures safety. Zinc spraying is a type of "thermal spraying" anti-corrosion technology, commonly used in the manufacturing of welded steel cylinders (such as common household gas tanks). The process is mainly divided into the following steps:

1. Surface Pretreatment (Critical Step)
Shot Blasting/Sandblasting: The cylinder surface is subjected to high-speed impact using steel shot. The purposes are: to completely remove rust, oxide scale, and old coatings; to roughen the surface (achieving a certain roughness level, e.g., Sa 2.5 or above), creating an "anchor pattern effect" that greatly enhances the bond strength between the zinc coating and the substrate.

2. Zinc Spraying Operation
Equipment: Arc spraying equipment is used.
Material: Pure zinc wire or zinc alloy wire is used as the spraying material.
Process: In the spray gun, the zinc wire is instantly heated to a molten state by an electric arc. Simultaneously, compressed air atomizes the molten zinc and sprays it at high velocity onto the pretreated cylinder surface. These tiny zinc particles impact the surface, rapidly flatten, cool, and stack, forming a porous zinc coating.

3. Post-treatment and Sealing
Cooling and Inspection: After spraying, the coating is cooled and inspected for appearance, thickness, and uniformity.
Sealing Treatment (Optional but Recommended): Due to the inherent microscopic pores in the sprayed zinc layer, a "sealing treatment" is often applied to improve protective performance. This involves spraying or brushing a dedicated sealer (such as diluted epoxy resin, phosphating solution, or passivation solution), allowing it to penetrate the pores and form a denser composite coating.

4. Subsequent Painting
A layer of topcoat (typically epoxy resin paint or polyurethane paint) is usually sprayed over the zinc layer (and sealing layer, if applied).
The functions of the topcoat are: to provide an additional physical barrier, enhance appearance (providing various colors), resist UV degradation, and further isolate the substrate from corrosive media.

Main Advantages of the Zinc Spraying Process:
1. Long-lasting Cathodic Protection (Electrochemical Anti-corrosion)
This is the core advantage of zinc spraying. Zinc has a more negative electrode potential than iron (steel). When the coating is damaged or pores expose the substrate, zinc acts as a "sacrificial anode," corroding preferentially, thereby protecting the steel cylinder substrate from corrosion. Even if the topcoat is scratched, the underlying zinc layer still provides active protection.

2. Excellent Bond Strength
After rigorous sandblasting pretreatment, the bond between the sprayed zinc layer and the cylinder substrate is a combination of mechanical interlocking and micro-metallurgical bonding, resulting in very strong adhesion that is not prone to peeling.

3. Good Corrosion Resistance and Durability
In various environments such as industrial, rural, and marine atmospheres, the anti-corrosion service life of the zinc spray composite coating can reach 15-30 years or more, far exceeding that of simply painted cylinders (typically only 5-10 years).

4. High-Temperature Resistance
The melting point of pure zinc is approximately 419 C. Sprayed zinc coatings can withstand higher temperatures than organic coatings, which is an advantage for cylinders exposed to summer sunlight or briefly near heat sources.

5. Strong Adaptability to Cylinder Shape
The spraying process is flexible and can uniformly cover all external surfaces of the cylinder, including the shell, heads, welds, and even complex shapes.

6. Balance of Economy and Safety
Compared to using stainless steel throughout, zinc spraying is a more economical enhanced anti-corrosion solution. It significantly delays wall thinning caused by external corrosion, fundamentally eliminates the risk of leakage due to corrosion perforation, and enhances the product's safety and reliability.

Summary:
In LPG cylinder manufacturing, adopting the composite coating system of "Sandblasting Pretreatment + Zinc Spraying + Sealing + Topcoat" is a widely used, high-standard anti-corrosion solution. It combines the cathodic protection of a sacrificial anode with the physical barrier protection of an organic coating, achieving the dual effect of "active anti-corrosion" and "passive anti-corrosion." It is a key process to ensure the long-term safe use of this type of pressurized, flammable, and explosive container in harsh environments.

Definition of Arc Spraying:
Arc spraying is widely used in industry. It is a technique that uses an arc burning between two continuously fed metal wires to melt the metal, atomizes the molten metal with a high-speed airflow, and accelerates the atomized metal particles to spray them onto the workpiece, forming a coating. Arc spraying is one of the most commonly used thermal spraying methods in practical engineering applications such as corrosion protection of steel structures, wear resistance, and repair of mechanical parts.

An arc spraying system generally consists of a dedicated power supply for spraying, control equipment, an arc spray gun, a wire feeder, and a compressed air supply system. Materials come in various forms such as powder, wire, tape, and rod, with compositions including metals, alloys, ceramics, cermets, and plastics. Powder materials hold a significant position, with over a hundred types available. Wire and tape materials are mostly metals or alloys (composite wires may also contain ceramics or plastics). Rod materials are limited to about a dozen types, mostly oxide ceramics.

Arc spraying materials are typically in wire form, such as zinc wire, aluminum wire, aluminum alloy wire (Ac aluminum, AS aluminum), copper wire, etc. Powder materials are mainly used in flame spraying.

High-power arc spraying machine is a new generation of thermal spraying equipment. It integrates over a decade of design and manufacturing experience with technological innovation, combining all the advantages of similar devices in the industry. With its perfect appearance design, intelligent spraying control, pure copper core, high power, and fast loading capability, it stands out as a leader in the industry both domestically and internationally.

Applicable Spraying Methods: High-speed pull-type spray gun, push-type spray gun (requires wire feeder)
Input Power: 3-phase AC 380V 50Hz
Input Current: AC 22A
Output No-load Voltage: DC 21-45V
Power Characteristics: Flat characteristic
Output Current: DC 300A, 400A, 600A, 1000A
Duty Cycle: 80% (300A, 400A, 600A, 1000A)
Insulation Class: Class B
Input Power: 15.8KVA, 18.8KVA, 32.6KVA, 42.6KVA, 53KVA
Voltage Adjustment Levels: 9 levels with integrated coarse and fine tuning
Dimensions: 800*500*900mm
Weight: 260 kg
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