Scrap metal refers to metal fragments and debris discarded by industries and metal processing, as well as metalware discarded after equipment upgrades. It also includes metal packaging materials, scrap cars, and other metal items collected from municipal waste. Scrap metal is a resource, and specialized companies worldwide specialize in scrap recycling. Scrap metal is primarily used for smelting and reuse, with some used in the production of industrial equipment and parts, tools, and consumer electronics. The main sources of scrap metal are as follows:

1. Internal Scrap Metal
This is scrap metal generated within manufacturing companies and reused as raw material for their own production. Typically, this scrap metal does not enter the market.

2. Processed Scrap Metal
This is scrap metal generated by domestic metal manufacturing companies and returned to metal recycling plants for reuse as raw material. Typically, this scrap metal returns to recycling plants within a few weeks of its generation, hence the name "short-term scrap metal."

3. Depreciated Scrap Metal
This is scrap metal generated when metal products reach the end of their useful life and are scrapped. Since the formation of depreciated scrap metal requires several life cycle stages such as metal production, manufacturing of metal products, use, scrapping and recycling, which generally takes several years or even more than ten years, depreciated scrap metal is also called "long-term scrap metal".

316 stainless steel pipe is widely used for its excellent corrosion resistance, high strength, and good processability. However, in some extreme operating conditions or where the purity of the medium is extremely high, the inherent properties of 316 stainless steel alone may not meet the requirements. In such cases, coating the inner wall of 316 stainless steel pipe is necessary to enhance its performance and expand its application range.

Surface Pretreatment
Before coating, surface pretreatment of the inner wall of 316 stainless steel pipe is crucial. First, mechanical cleaning, such as using a dedicated pipe cleaning brush or high-pressure water jet, removes impurities such as oil, rust, and welding slag from the inner wall. Chemical cleaning, using an appropriate acid or alkaline solution, further removes oxide films and residual impurities from the metal surface. Finally, surface roughening treatment, such as sandblasting or electrolytic etching, increases the surface roughness and improves adhesion between the coating and the substrate.

Coating
A variety of coating methods are available, depending on the coating material and application requirements. PTFE coatings are often applied by spraying. PTFE powder is mixed with a binder and evenly applied to the pipe's interior using a high-pressure spray gun. The coating is then cured by high-temperature sintering. Epoxy resin coatings can be applied by brush, roller, or high-pressure airless spray, creating a uniform coating on the pipe's interior. The coating is then cured at a specific temperature. Ceramic coatings are often applied using thermal spraying techniques, such as plasma spraying and supersonic flame spraying. Ceramic powder is heated to a molten or semi-molten state and then sprayed onto the pipe's interior at high speed, forming a dense ceramic coating.

Post-Processing
After coating, post-processing is required. To further enhance coating performance, heat treatment, such as high-temperature baking, can be performed to stabilize the coating's molecular structure and enhance its hardness and wear resistance. Coating quality is also tested. Visual inspection, coating thickness gauges, and adhesion tests are used to check whether the coating meets requirements for thickness, uniformity, and adhesion, ensuring the coating meets the desired standards.

Wide Range of Applications for Finned Tubes

As a highly efficient heat transfer element, finned tubes play a vital role in a variety of industrial sectors due to their excellent heat dissipation performance and structural features. Their primary applications include: 

Industrial Cooling Systems

Finned tubes are widely used in industrial cooling systems such as refrigeration units, air conditioning equipment, and fan cooling systems. Their efficient heat dissipation allows them to quickly transfer heat to the surrounding environment, ensuring stable operation of the equipment. They are ideal for temperature control in industries such as the chemical and machinery manufacturing industries.

Petrochemical Industry

In the petrochemical industry, finned tubes are an ideal choice for key equipment such as reactors, heat exchangers, and steam generators. Their corrosion resistance and customizable material options (such as stainless steel, carbon steel, and copper-aluminum composites) enable them to meet heat transfer requirements under diverse process conditions, improving production efficiency.

Power Industry

Finned tubes are commonly used as heat dissipation or heating elements in power plant boilers, gas turbines, and hydropower equipment. Their excellent thermal conductivity effectively regulates the temperature of the medium, ensuring stable operation of power generation equipment while improving energy efficiency.

Refrigeration Equipment

Fin tubes are widely used in core components such as condensers and evaporators in the refrigeration industry. By optimizing heat dissipation efficiency, they not only improve cooling performance but also reduce energy consumption. They are suitable for applications such as commercial refrigerators and industrial refrigeration systems.

Heating Systems

In systems such as hot water circulation and steam heating, fin tubes can significantly increase heat exchange rates, ensuring rapid and uniform heating. They are suitable for applications such as HVAC and district heating.

Electronic Equipment Cooling

As the power density of electronic devices continues to increase, fin tubes, with their compact structure and efficient heat dissipation, are widely used in cooling modules for devices such as servers, 5G base stations, and high-power LEDs, ensuring long-term and stable operation.

Summary

From industrial cooling to electronics cooling, from petrochemicals to power generation, fin tubes, with their flexible design and excellent performance, have become an indispensable component in modern heat exchange systems. With advances in material technology and manufacturing processes, their application will continue to expand.