月: 2023年1月

What Is Welded Pipe?

Welded pipes, typically made from steel, are formed by shaping a steel strip into a circular structure and joining the seams using electric resistance welding. These pipes are also known as ERW (Electric Resistance Welded) pipes.

Characterized by their thin walls and continuous manufacturing process, welded pipes can be produced cost-effectively in large quantities. They are available in various diameters, from small (6A) to large (700A). Various materials, including carbon steel, stainless steel, and low-alloy steel, are used for manufacturing welded pipes. However, weld marks may remain on these pipes, requiring additional finishing if appearance is a concern. Welded pipes are extensively used for piping, automotive parts, machinery, and building structures.

Uses of Welded Pipe

Welded pipes offer versatility in terms of material, diameter, thickness, and length. They are employed in various applications, such as:

• Construction: Steel pipe piles, sheet piles, scaffolding, foundation piers, and structural components.
• Transportation: Parts for automobiles, bicycles, and machinery.
• Utilities: Piping for water, sewage, steam, gas, air, and high/low-temperature environments.
• Industrial: Boiler water pipes, flue gas pipes, heaters, and heat exchangers.
• Hydraulic and pneumatic systems: Cylinder tubes for hydraulic and pneumatic cylinders.

Alloy steel pipes, such as stainless steel sanitary tubing, are also used in the dairy, food, medical, and pharmaceutical industries.

Principles of Welded Pipe

Welded pipes are made from coiled steel strips that are uncoiled, leveled, and processed at the edges. The strip is shaped into a circular form and welded using methods like high-frequency resistance welding, high-frequency induction welding, or electric resistance welding. These processes involve heating the joint area to high temperatures and pressing it together to form a seamless bond.

The welded pipe is then cut, cooled, and straightened to achieve the desired specifications.

Types of Welded Pipe

Welded pipes can be categorized into two primary types based on the material:

• Carbon Steel Welded Pipes: Commonly used for structural purposes, these pipes are made from various grades of carbon steel, from low to high carbon content.
• Alloy Steel Welded Pipes: These include stainless steel, chromium/molybdenum steel, and high manganese steel pipes, used for specific applications like sanitary pipes, boilers, and heat exchangers. Stainless steel, known for its corrosion, oxidation, and heat resistance, is often used in high and low-temperature environments. Chromium molybdenum steel is characterized by its heat and pressure resistance, suitable for thermal power plants and oil refineries.

Standards and Differences from Seamless Pipes

Welded pipes conform to various standards, including those for general structural purposes, machine structures, piping, and heat exchangers. The manufacturing method is indicated by the symbol “E” for electric resistance welding. The finishing method is also denoted, with “H” for hot finishing, “C” for cold finishing, and “G” for no finishing.

Compared to seamless pipes, which are made from solid round bars, welded pipes are less expensive but not as strong, especially in terms of internal pressure and torsion resistance. While seamless pipes offer higher dimensional accuracy and smoother surface properties, they tend to be costlier.

What Is a Structural Pipe?

Structural steel pipes, made of steel, are used in construction and civil engineering. These pipes are either circular or square in cross-section, the latter being known as square steel pipes.

There are various types of structural pipes, most of which are standardized. Common types include carbon steel tubes for general structures (STK), used in construction, civil engineering, support pillars, steel towers, and machine parts. Rectangular structural steel pipes (STKR) are used in construction and civil engineering. For mechanical components in automobiles, construction machinery, industrial machinery, and steel furniture, carbon steel structural pipes (STKM) are utilized. Small square structural pipes (STKMR) find application in automobiles and steel furniture.

Carbon steel structural pipes (STKN) are known for good weldability and are primarily used in building structures. Other types include electric resistance welded carbon steel pipes for automobile structures (STAM), high tensile strength steel pipes for steel towers (STKT), and stainless steel pipes for machine structures (SUS-TK).

Applications of Structural Pipes

Structural pipes are employed in a variety of fields, including:

• Building components: Supporting steel frames in buildings, warehouses, apartments, multi-story parking garages, roof supports in stadiums and stations, and earthquake-resistant braces.
• Landscape structures: Supporting road signs, traffic signals, guardrails, lighting, railroad overhead lines, and signals.
• Amusement equipment: Components in parks and theme parks such as slides, bars, jungle gyms, Ferris wheels, and roller coasters.
• Bridges: Pedestrian bridges, piping bridges, and construction walkways.
• Offshore structures: Foundations for offshore wind turbines, floating piers, and tsunami barriers.
• Civil engineering: Steel pipe piles, foundation piles for sound insulation walls, temporary scaffolding, etc.
• Transportation equipment: Conveyor rollers, logistics racks, pallets, and automotive paint hanger materials.

Characteristics of Structural Pipes

Structural pipes are characterized by their circular cross-section, which imparts no directionality and provides high strength against compression and torsion. They offer greater wind resistance than shaped steel, allowing for lighter and more economical designs. Their lightweight nature also reduces transportation costs and facilitates the handling of larger units. The round and smooth appearance of these pipes adds an aesthetic appeal.

Structural pipes are manufactured using various methods. Electric resistance welding involves forming hot-rolled coils into tubes and joining them with high-frequency resistance welding. Seamless steel pipes are produced from round steel billets that are heated and hollowed out. Longitudinally Submerged Arc Welded (LSAW) pipes are created by forming and seam welding thick plates. Spiral steel pipes are made by forming hot-rolled coils into a spiral shape and seam welding using the submerged arc welding method.

What Is a Nuclear Magnetic Resonance (NMR) Analyzer?

Nuclear magnetic resonance (NMR) analyzers determine the chemical environment of atoms, identifying elements in the surrounding environment and bonding states to elucidate the structure of the analyzed compound.

The results from NMR analyzers are depicted with the chemical shift on the horizontal axis—representing the frequency difference between the NMR signal of the reference substance and the analyzed substance—and intensity on the vertical axis.

Figure 1. Example of NMR Measurement Results

NMR analyzers, capable of evaluating specific elemental species during measurement, offer detailed insights for each element, even in complex compounds. They accommodate a diverse array of samples, including liquids, solids, and gel-like substances.

While Raman spectrophotometers and electron microscopes also facilitate structural analysis, NMR analyzers provide simple, nondestructive analysis, offering comprehensive structural information, including data on neighboring atomic species.

Applications of NMR Analyzers

NMR analyzers find applications beyond materials analysis, extending into clinical fields, as highlighted below.

1. Material Analysis

NMR excels in analyzing organic materials, including resins, biomaterials, and electrolytes for batteries, aiding in structural elucidation and degradation cause analysis.

It clarifies structures of synthesized or purified substances, identifies molecular weight components, assesses purity, detects impurities, and facilitates quantitative analysis through database comparisons.

2. Clinical Applications

MRI (magnetic resonance imaging), utilizing NMR principles, visualizes the body’s water distribution, offering detailed tissue state images without radiation exposure risks, surpassing CT scans in resolution and detection capabilities.

Principle of NMR Analyzers

1. Nuclear Magnetic Moment

Figure 2. Nuclear Magnetic Moment

An atom’s nucleus, positively charged and spinning, generates a magnetic field, effectively making each atom a small magnet. This field’s magnitude is the nuclear magnetic moment.

2. Zeeman Splitting and Resonance

Figure 3. Zeeman Splitting

In a strong magnetic field, nuclei split into two energy states, a phenomenon known as Zeeman splitting. Resonance occurs when electromagnetic waves matching the energy gap induce transitions, enabling the identification of atomic environments.

Zeeman splitting allows observation of varied nuclear compositions, excluding atoms like 12C and 16O, which lack nuclear magnetic moments due to their even mass and atomic numbers.

3. Chemical Shift

Resonance frequencies vary with the nucleus’s environment, measured as the chemical shift in ppm from the reference material’s resonance frequency.

Other Information on NMR Analyzers

NMR Analyzer Cautions

NMR analyzers’ strong magnetic fields attract metal objects and may damage pacemakers, credit cards, and smartphones. The magnets, cooled with liquid helium, require careful management to prevent asphyxiating gas release during abrupt temperature rises.

What Is Tool Steel?

Tool Steel is a steel material used for cutting, forming, and other tool steel applications, with properties such as high hardness, wear resistance, heat resistance, and corrosion resistance.

Tool steel is classified into three types: carbon tool steel, alloy tool steel, and high speed tool steel.

Carbon tool steel is the most commonly used tool steel. Alloy tool steel is a special type of tool steel used for cutting, forming, and other tool steel applications due to its high hardness, wear resistance, heat resistance, and corrosion resistance.

Alloy Tool Steel is available for cold or hot molds, while high speed tool steel includes tungsten-based and molybdenum-based tool steels.

Uses of Tool Steel

The following are examples of major uses of tool steel.

1. Cutting Tools

Cutting tools for lathes, milling machines, drill bits, etc.

2. Rolling Tools

Rolling tools for processing metal sheets and bars, press dies for forming metal bars, etc.

3. Dies

Molds for forming plastic and metal.

4. Control Device Parts

Parts for machinery such as automobiles and aircrafts.

5. Electronic Parts

Tubes for high-frequency heaters, vacuum tubes, etc.

6. Cutting Tools

Blades such as kitchen knives, scissors, cutter blades, etc.

7. Bearings

High-hardness, wear-resistant bearing parts used in high-load rotating parts.

Types of Tool Steel

As previously mentioned, tool steel is classified into three types: carbon tool steel, alloy tool steel, and high speed tool steel.

1. Carbon Tool Steel

Carbon tool steel is a high-carbon steel mainly used for tools such as cutting tools and dies. It generally has high hardness and excellent wear resistance, heat resistance, and corrosion resistance.

2. Alloy Tool Steel

Alloy tool steel generally has high hardness, wear resistance, heat resistance, and corrosion resistance, and is used in the manufacture of tools and dies.

3. High-Speed Tool Steel

High-speed tool steels are generally classified into three groups: tungsten-based, molybdenum-based manufactured by powder metallurgy, and molybdenum-based. There are a total of 15 types of steel available under this category.

Tungsten-based high-speed tool steel is a type of tool steel that contains tungsten as the main alloying element, and has properties such as high hardness, wear resistance, heat resistance, and machinability. It is mainly used in the manufacture of tools and dies for cutting metals, and is suitable for cutting operations at high speeds.

Molybdenum-based high-speed tool steel is a type of tool steel that contains molybdenum as a major alloying element and is characterized by high wear resistance, heat resistance, and toughness when cutting at high speeds.

Molybdenum-based high-speed tool steel produced by powder metallurgy has a uniform structure and density, and can exhibit high wear resistance, heat resistance, and toughness. In addition, the uniform blending and sintering generally results in higher hardness and longer life than conventional steels.

Properties of Tool Steel

The main properties of tool steels are as follows:

1. Hardness

Tool steel is characterized by its high hardness and its ability to withstand high-load operations such as cutting and machining. It is used in the manufacture of tools, dies, and other parts for which durability is required. 

2. Wear Resistance

Tool steel has excellent wear resistance and can withstand long-term use. It is widely used for high-speed cutting tools and molds because it is resistant to deformation and wear caused by friction and heat generated during cutting and machining operations.

3. Heat Resistance

Tool steel is resistant to deformation and heat softening even under high heat conditions. Therefore, it is suitable for work in high-temperature environments, such as high-temperature cutting and casting processes.

4. Malleability

Tool steel is suitable for forging operations and can be formed into various shapes. Therefore, it is suitable for manufacturing parts that require high precision, such as molds and blades with complex shapes.

5. Steel Grades

There are various types of tool steel, such as high speed steel, high carbon steel, and special tool steel. Each steel grade has different characteristics, and the appropriate steel should be selected for each application.

Other Information on Tool Steel

1. Dimensional Stability

Tool steel is required to have high hardness, wear resistance, heat resistance, and corrosion resistance, so it is important to have less deformation and wear even after being used for a long period of time.

In addition, products and parts made of tool steel are sometimes required to have high form accuracy. Tool steel is made to have high dimensional stability and little change in shape after heat treatment.

To improve dimensional stability, it is important to remove impurities from the steel and to apply appropriate heat treatment. For example, impurities in steel, such as oxides and carbon, can react at high temperatures, causing oxidation and alteration, so the production of tool steel includes a refining process at high temperatures.

Heat treatment is also an important process used to adjust mechanical properties such as hardness and strength by changing the properties of the steel.

2. Corrosion Resistance

Since tool steel is often used in humid and corrosive environments, corrosion resistance is another important property. Molds and cutting tools, for example, may come in contact with moisture or corrosive materials, which can shorten the life of parts and products.

Corrosion resistance is especially important for tools and dies that come into contact with corrosive materials, such as plastics and food processing.

In general, the corrosion resistance of tool steel can be improved by the addition of alloying elements or special treatments. For example, chromium, molybdenum, or other alloying elements may be added to improve corrosion resistance.

Another feature is that the corrosion resistance of tool steel can be improved by appropriate heat treatment or surface treatment.

3. Control of Mechanical Properties

Tool steel has various mechanical properties depending on the constituent materials and heat treatment. The main mechanical properties of tool steel are hardness, strength, toughness, fatigue strength, heat resistance, wear resistance, and corrosion resistance. These mechanical properties are controlled by the amount of alloying elements added, the cooling method, and the type and conditions of heat treatment.

In general, heat treatment of tool steel includes quenching, tempering, annealing, and surface hardening. Quenching is a method of increasing the hardness of tool steel by heating it to a high temperature and then cooling it rapidly.

Tempering is a method of softening hardness by heating and cooling again after quenching. Annealing improves the toughness of tool steel by heating it at a low temperature for a long time. Surface hardening is a method of increasing hardness by heating the surface with high frequency.

The amount of alloying elements added to tool steel is also important to control mechanical properties such as hardness, strength, and toughness.

Common alloying elements include chromium, vanadium, molybdenum, cobalt, tungsten, manganese, silicon, nickel, and copper. By adding these alloying elements, the properties of tool steel can be adjusted.

What Is Expanded Metal?

Expanded metal is a versatile material formed through processes like rolling, forging, drawing, extruding, or other means of shaping metal into various forms such as plates, strips, bars, wires, tubes, and profiles. These forms exhibit the inherent physical properties of their metal constituents, generally characterized by hardness, strength, and durability.

Its applications span across architecture, automotive parts, furniture, and interior design. In construction, expanded metal contributes to steel structures, while in the automotive sector, it’s integral to components like engine parts, suspensions, and wheels. Additionally, it finds utility in furniture and interior design contexts.

Uses of Expanded Metal

• Construction: Utilized in building steel structures, steel roofing for malls, and large sports facility frameworks.
• Automobiles: Forms parts of automobile engines, suspension systems, and wheel rims.
• Furniture and Interiors: Used in manufacturing steel chair legs and metal wall clocks.
• Mechanical Parts: Integral to the production of gears, bearings, and various types of springs and wheels.
• Electronic Equipment: Found in PC cases, power supply unit enclosures, and frames for audio equipment.

Principles of Expanded Metal Production

• Rolling: Metal sheets or bars are stretched under pressure, using cold or hot methods, for flexibility and complex shapes.
• Forging: Heating and pressurizing metal to enhance its strength and durability through a uniform structure.
• Drawing: Drawing metal through a die to produce thin parts like wires and pipes.
• Extrusion: Passing metal through a die to extrude it into desired shapes such as tubes or bars.
• Draw Work (Stretching Process): A method suitable for thin sheet materials, drawing metal through a die.
• Hot Drawing: Heating metal before drawing through a die for thin parts production.

Types of Expanded Metal

• Material: Includes steel, aluminum, copper, stainless steel, titanium, nickel alloys, and other alloys.
• Shape: Varieties include plates, bars, wires, tubes, and profiles with distinct cross-sections like H-beams and I-beams.
• Applications: Ranging from construction materials to automotive parts.
• Manufacturing Method: Encompasses rolling, forging, drawing, and other techniques.

Other Information on Expanded Metal

Expanded metal undergoes various surface treatments to enhance its material characteristics, appearance, and durability. These treatments include rustproofing, painting, coating, plating, quenching, and, where necessary, heat treatment to improve fatigue resistance by controlling the metal’s internal microstructure.

• Pickling Treatment: Cleans the metal’s surface by removing oil, grease, and oxides using acid.
• Plating Treatment: Enhances appearance and corrosion resistance through metal plating, including zinc, chromate, nickel, chrome, silver, gold, and tin plating.
• Coating Treatment: Applies coatings to improve color, appearance, and resistance to rust and corrosion. Coatings include epoxy, urethane, acrylic, and fluorine resins.
• Anodizing: Covers the surface of light metals with an oxide film to harden it and improve corrosion resistance, wear resistance, and electrical insulation.
• Passivation Treatment: Improves strength and corrosion resistance by forming a protective oxide film on metals like stainless steel and titanium.
• Heat Treatment: Employs high temperatures to enhance the metal’s structure, hardness, and strength, and reduce brittleness through methods like quenching and tempering.

What Is an Electronic Conductive Material?

Electronic conductive materials are substances that contain free electrons, allowing them to conduct electricity.

Common electronic conductive materials include metals, semiconductors, and conductive polymers. Metals, due to their free electrons, are highly conductive. Semiconductors exhibit lower conductivity, which can be enhanced and controlled through doping and other methods. Conductive polymers are noted for their flexibility, lightweight, and adjustable conductivity, attributed to charged portions within their molecules.

These materials find extensive use in electronic devices, circuits, sensors, lighting solutions, electric vehicles, and solar cells.

Applications of Electronic Conductive Materials

Electronic conductive materials are crucial in:

1. Electronic Devices

Examples include transistors, diodes, and integrated circuits, with semiconductors like silicon being a primary material. Transistors amplify and switch electrical signals, while diodes allow current to flow in one direction.

2. Electric Circuits

Found in wiring and printed circuit boards, where conductive paths connect components.

3. Sensors

Used in acceleration sensors, pressure sensors, and temperature sensors.

4. Lighting

Key in LEDs and fluorescent lamps, where semiconductors emit light upon electrical flow.

5. Transportation Equipment

Integral to trains, electric vehicles, elevators, and automatic doors.

Types of Electronic Conductive Materials

These include:

1. Metals

Highly conductive materials such as copper and aluminum, are known for their free electron movement.

2. Semiconductors

Materials like silicon, with controllable conductivity through impurity addition.

3. Electrolytes

Ionic compounds that conduct electricity through ion movement, utilized in batteries and sensors.

4. Conductive Polymers

Flexible materials used in organic electronic devices.

5. Others

Advanced materials like carbon nanotubes and graphene, offering unique electrical properties.

Properties of Electronic Conductive Materials

1. Conducts Electricity

The presence of free electrons enables these materials to conduct electricity.

2. Low Electrical Resistance

A well-ordered crystal structure ensures minimal resistance by reducing electron-atom collisions.

3. High Thermal Conductivity

Efficient heat transfer is achieved through the orderly movement of free electrons.

4. Electricity Generates a Magnetic Field

The flow of electric current through these materials generates a magnetic field.

Other Information on Electronic Conductive Materials

1. Addition of Impurities to Semiconductor Materials

Intentional impurity addition modifies electrical properties, enabling the creation of p-type and n-type semiconductors.

2. Flexible Conductor Materials

Materials like conductive polymers and carbon nanotubes are flexible yet conductive, suitable for various applications.

3. High Temperature Resistance

Some materials, such as carbon nanotubes, retain conductivity at high temperatures.

4. Corrosion Resistance of Metal Electronic Conductive Materials

Metals like copper exhibit high corrosion resistance, beneficial for longevity in applications.

What Is Alloy Steel?

Alloy Steel is a type of steel made from combining carbon steel with one or more elements known as alloys. Physical and chemical properties vary according to their composition.

Alloy Steel generally contains elements such as carbon, chromium, nickel, molybdenum, manganese, and vanadium, which combine with iron to improve the steel’s strength, corrosion resistance, wear resistance, durability, and machinability.

Alloy Steel can be produced in a variety of ways, but it is generally formed by mixing iron and the elements to be added at high temperatures and then cooling.

Post-treatment such as heat treatment and fabrication may also be required.

Uses of Alloy Steel

1. Aircraft

Alloy Steel, such as stainless steel and titanium alloys, are used because high strength and high corrosion resistance are required. Examples include jet engine parts and landing gear. 

2. Automobiles

High tensile strength steels are especially used because of the high strength and hardness required. Examples include chassis and body panels.

3. Construction

Because strength and durability are required, steel materials with high earthquake resistance are used. Examples include high-rise buildings and bridges.

4. Energy

Alloy Steel with high heat and pressure resistance is used because it is required to be used in high temperature and high pressure environments. Examples include nuclear power plants and thermal power plants.

5. Medical Instruments

Alloy Steel such as stainless steel and titanium alloys are used. Examples include artificial joints and dental implants.

Implants are a type of medical device that are implanted inside the body and made from artificially created materials.

6. Tools

Alloy Steel such as high speed metal and molybdenum steel are used because of their wear and heat resistance. Examples include drills and cutting tools.

High-speed steel (HSS) is a type of high-performance steel made by adding alloying elements such as chromium, molybdenum, and vanadium to iron, and is widely used in cutting and machine tools since it can withstand high temperatures and cut and machine at high speeds.

Properties of Alloy Steel

The main properties of alloy steel are as follows:

1. Strength

Alloy Steel is stronger than pure iron and can withstand high loads and impacts. It is used in structures such as bridges, skyscrapers, and aircraft, as well as in automobile chassis and engine parts and tools.

2. Hardness

Alloy steel is tough and has high hardness. It is used for high-load parts such as tools, machine parts and gears.

3. Abrasion Resistance

High abrasion resistance prevents wear due to grinding and abrasion, and is used for high-load parts such as tools, machine parts, gears, and bearings.

4. Corrosion Resistance

Corrosion resistance is increased by added alloying elements. Alloy steels such as stainless steels are used in applications such as food processing equipment and medical instruments.

5. Heat Resistance

Alloy Steel has high heat resistance due to the alloying elements added. They are used for parts used in high-temperature environments and in nuclear power plants.

6. Corrosion Resistance

Alloy Steel has high corrosion resistance because the alloying elements added to the steel prevent the formation of oxides and corrosion products and protect the surface. Alloy steels are used in chemical plants, etc., taking advantage of their high corrosion resistance.

Types of Alloy Steel

There are many types of alloy steel. The following are typical examples:

1. Carbon Steel

Carbon Steel is an alloy steel in which carbon is the main alloying element and is composed only of iron and carbon. It is widely used because of its high strength and low-cost production.

2. Stainless Steel

Stainless steel is a steel to which chromium is added as a major alloying element. It has excellent corrosion resistance. It is suitable for applications such as food processing and medical equipment.

3. Tool Steel

Tool steel is a steel to which carbon, chromium, vanadium, and other alloying elements are added, featuring high hardness and high durability. It is widely used for cutting tools, dies, and machine tools.

4. Nickel Steel

Nickel steel is a steel to which nickel is added as the main alloying element, and is characterized by high strength and heat resistance. It is used in high-temperature environments such as aircraft and nuclear power plants.

5. Chromium Molybdenum Steel

Chromium molybdenum steel is a steel to which chromium and molybdenum are added as major alloying elements, and is characterized by high strength and durability. It is used for structural parts of automobiles, rolling stock, ships, etc., and for hydraulic equipment, etc.

6. Manganese Steel

Manganese steel is a steel to which manganese is added as the main alloying element, and is characterized by high wear resistance. It is used for railroad rails, construction steel, machine parts, etc.

7. Aluminum Steel

Aluminum steel is a steel in which aluminum is added as the main alloying element, is lightweight and has excellent corrosion resistance and workability. It is used for automotive parts, aircraft parts, construction materials, etc.

Other Information on Alloy Steel

1. Impact Resistance

Alloy Steel may become brittle due to its high hardness and strength. This is due to the fact that the blending of elements in alloy steel causes the crystal structure to become less uniform and localized crystal defects are more likely to occur. These defects can expand as stress is applied, eventually leading to fracture.

Alloy Steel is also harder and more brittle than ordinary steel, and can be easily damaged by impact.

2. Weather Resistance

Alloy Steel generally contains elements such as chromium, copper, phosphorus, silicon, and aluminum. These elements form an oxide film on the surface of the steel, preventing corrosion and deterioration. In particular, when chromium is added in large amounts, the oxide film is very tough and extremely resistant to corrosion.

Alloy Steel is therefore suitable for outdoor use. For example, it is used for automobile parts, building exteriors, bridges and other structures, ships, and wind power generation towers.  It is also used for parts and equipment used in harsh environments such as areas with strong salt damage and tropical regions.

However, weather resistance varies depending on the environment in which it is used, so appropriate alloy steel should be selected.

Periodic maintenance and repairs are necessary because corrosion progresses when the oxide film on the surface is damaged.

What Is a Disk?

A disk is a circular, flat component used in various industrial applications. It is typically made from various materials, including aluminum, copper, brass, ceramics, and acrylic resin. The choice of material and size is tailored to specific uses.

For instance, copper disks leverage their excellent electrical conductivity in electrical components, while ceramic disks are used as insulating plates due to their insulating properties.

Uses of Disks

Disks have diverse applications based on the material they are made from.

Chemical-resistant resin disks are used as flanges in piping systems in environments like chemical and semiconductor plants, fisheries, and food factories. Similarly, cushioning resin disks serve as shock-absorbing materials.

Copper disks, known for their high electrical conductivity, are often employed as electrical contacts or electrodes.

Stainless steel disks, due to their thin and durable nature, are used in products like lids and food trays.

Characteristics of Disks

The shape of disks plays a significant role in their application. The circular form is particularly advantageous in industries requiring rotational movement.

In the electric power sector, for example, disks are integral to generators and electric motors, where they facilitate the conversion of energy into rotational kinetic energy.

Electrical contacts, another common use of disks, typically feature a circular design.

In civil engineering and construction, cylindrical pipes for fluid flow are standard. Cylindrical shapes are also prevalent in devices like telescopes, where they offer optical benefits.

The widespread use of circular devices and equipment, including disks, underscores the circle’s versatility and indispensability in various fields.

What Is Galvanized Wire?

Galvanized Wire is steel wire that has been coated with zinc plating on drawn mild steel wire.

High corrosion resistance can be expected due to the anti-corrosion effect of the zinc coating.

Uses of Galvanized Wire

Although stainless steel is the other more corrosion-resistant metal, galvanized wire is often chosen for its balance of cost and corrosion resistance.

Galvanized wire is also used in familiar applications, such as wire mesh for fences, packing material for automobile spark plugs, hose clips, wire brushes, and other tools. In civil engineering and construction, it is used in nets to prevent rocks from falling from cliffs, as well as for binding wire for reinforcing bars inside reinforced concrete, and as barbed wire.

Other uses include materials used in the electrical field, such as auxiliary wires supporting electrical cables and submarine power cables, as well as in the agricultural and fishing industries.

It is versatile enough to be used in a wide range of industries and in general life, with specifications that can be selected according to the application.

Features of Galvanized Wire

1. Galvanized Wire (S)

Galvanized wire (S) is made by first cold working mild steel wire. Then the wire is annealed and galvanized. The annealing process softens the wire and improves workability, but reduces strength.

2.Galvanized Wire (H)

Galvanized wire (H) is galvanized without annealing after cold working. It is not as soft, but has superior strength.

Other Information on Galvanized Wire

1. Types of Galvanizing Methods

Hot dip galvanizing method
Hot dip galvanizing is a process in which the material is immersed in a zinc bath at about 450°C to deposit a zinc coating on the surface. The coating is then stabilized by cooling with warm water in a subsequent process.

The alloy layer formed between the zinc coating and the steel substrate bonds the zinc and the steel substrate strongly, so that the plating film does not peel off even after a long period of time, achieving high adhesion.

Electrogalvanization Method
Electrogalvanization is a process in which a zinc coating is deposited on steel materials through a reduction reaction caused by electric current. It is suitable for processing products that require high precision because it can deposit a thinner and more uniform coating than hot dip galvanizing.

Although chromate treatment, which produces a chromium rust-preventive film, is required due to the thin film, it has an advantage in subsequent processing.

Corrosion Resistance Mechanism

Protective coating action
Protective coating action is a phenomenon in which the surface of the zinc coating reacts with oxygen and carbon dioxide to form an oxide film. This film has a dense crystalline structure and is stable and impervious to oxygen and moisture, thus slowing down the corrosion rate.

It can be maintained in water or soil, but if strongly acidic or alkaline substances adhere to it, the oxide film is destroyed and the protective coating action is lost.

Sacrificial Corrosion Protection
Sacrificial corrosion protection is a phenomenon in which the surrounding zinc component becomes the anode and preferentially dissolves even if the galvanized coating is scratched and the underlying iron is exposed. This prevents corrosion of the steel and electrochemically protects the substrate.

What Is Duplex Pipe?

A duplex pipe is a type of tubing that consists of concentric inner and outer tubes of different diameters. This dual-tube design safeguards against flow loss from inner tube damage and facilitates the heat exchange between liquids and gases flowing within the inner tube. Certain designs allow for absorbing external air fluctuations by securing the inner and outer tubes in distinct manners.

Applications of Duplex Pipe

1. Environmental Preservation Applications

The outer tube is designed to protect the inner tube from damage and fluid loss, thereby preventing environmental contamination.

2. Heat Exchanger Applications

Duplex pipes are commonly used in heat exchangers, facilitating heat transfer between the gas or liquid in the inner tube and the fluid in the outer tube. Their design minimizes fluid clogging and allows for a compact configuration by coiling the tubes. Duplex pipes support both parallel and counter flow, with enhanced performance achievable by adding fins to the inner or outer surfaces of the tubes. In refrigeration cycle heat exchangers, fins are often added to the waterside to improve heat transfer efficiency significantly.

3. Double-Piping Applications

An everyday use is in bathtub hot water systems, where hot water circulates between the heater and the tub through the gap between the pipes. This design is also employed in the air supply and exhaust for FF heaters, using the outer pipe for intake and the inner pipe for exhaust, demonstrating its utility in wall penetrations and HVAC ducts.

4. Double-Wall Construction Applications

The duplex pipe’s double-wall configuration, with no space between the tightly sealed inner and outer tubes, is ideal for environments with differing corrosion conditions between the tubes. This construction is utilized in thermal power condensers, as well as heat exchangers in refining and petrochemical plants, combining materials like carbon steel, brass, and stainless steel for cost efficiency and corrosion resistance.

5. Medical Applications

Duplex pipes are utilized in medical tracheostomies for both inhalation and exhalation processes.

6. Civil Engineering Applications

These pipes are employed to transport two different chemicals that combine at the endpoint to condition-specific soil areas.

Principle of Duplex Pipe

The features and capabilities of duplex pipes vary with the material combination of the inner and outer tubes. Utilizing materials with high heat conductivity for both tubes enables their use as efficient heat exchangers. Transparent outer tubes allow quick detection of inner tube issues, while strong, clear materials can prevent cracks and leaks. Such combinations are particularly valuable in applications requiring high reliability, like automotive piping. Transparent materials also facilitate constant monitoring of the water level within the pipes, and nozzle-shaped ends enable applications such as sprayers.

Other Information on Duplex Pipe

1. Hazardous Substances Designation

Substances such as cadmium, cyanide compounds, organic phosphorus compounds like parathion, lead, hexavalent chromium compounds, arsenic, mercury and its compounds, polychlorinated biphenyls, and trichloroethylene fall under the category of hazardous substances.

2. Use of Duplex Pipe

Duplex pipes offer a straightforward and cost-effective solution for complying with these regulations. Their use in hazardous substance piping allows for visual inspection and immediate detection of leaks, especially when the outer tube is transparent. This applies to the pipe’s main body, as well as fittings, flanges, valves, and pumps through which hazardous substances flow.