Other Welding Processes
Thermite Welding: This is a specialized welding process that generates heat through a highly exothermic chemical reaction rather than using a gas fuel or an electric current. The process involves igniting a mixture of finely powdered aluminum and iron oxide, commonly referred to as "thermite."
Thermite Welding
When ignited, this mixture undergoes a chemical reaction that produces molten iron and aluminum oxide while generating temperatures exceeding 4,500°F (2,500°C). The molten iron created by this reaction is then directed into a mold positioned around the joint area to fuse two metal components together, typically steel. Once the molten iron fills the joint and cools, it solidifies, forming a strong metallurgical bond between the pieces.
Thermite welding is most commonly used in heavy-duty applications where large steel components need to be joined, such as railroad tracks, pipelines, and structural steel components.
Laser Welding: Laser welding uses a focused beam of light to achieve very precise welds.
Laser Welding
The primary hazard of this powerful beam is to the eyes, which can be partially blinded when hit with the beam. Special eye protection must be used, and care must be taken with any reflective surfaces since both the original and reflected beams are extremely dangerous.
Electron Beam Welding: This method uses a focused beam of electrons to produce high precision and deep penetration welds.
Electron Beam vs. Laser Welding
Since x-rays are produced as a by-product, the process should be enclosed and shielded with lead or other materials suitable for preventing x-ray exposure. All doors, ports, and other openings must have proper seals and should be checked periodically to prevent x-ray leakage.
Operators should wear film badges to detect accidental radiation exposure. The high voltages required also present an electrical hazard.
Induction Welding: Induction welding is a contactless welding technique that uses electromagnetic induction to generate heat in a conductive material, creating a strong bond between components.
How Induction Welding Works
It works by passing high-frequency alternating current (AC) through a coil, which produces an electromagnetic field. When a conductive material is placed within this field, electrical currents, known as eddy currents, are induced in the material, causing it to heat up. Once the material reaches the required temperature, pressure is applied to fuse the components together, forming a strong and durable weld.
Friction Stir Welding (FSW): is a solid-state welding process in which a rotating, non-consumable tool is pressed into the joint between two materials, generating frictional heat. This heat softens (without melting) the materials, allowing them to mix and form a weld joint as the tool moves along the seam. A typical application is joining aluminum sheets in aircraft manufacturing.
An employee was prepping steel using a grinder. He was working by himself on the first level of an oil rig platform sub-base.
The worker was using a grinder and was standing inside a recessed box, where oxygen-acetylene torch hoses were also present. A leak from the acetylene hose provided the fuel source and a spark from the grinder provided the ignition source for a flash fire to occur.
The fire resulted in serious burns to his legs and feet. He was admitted to the hospital for ten days for burn injuries.
The investigation concluded the fire occurred due to a defective splice on the acetylene hose that allowed the acetylene to leak, causing a fire and the serious injury.
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1-7. What is the source of heat in thermite welding?
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