The Importance of Welding Dedusting Equipment

A welding environment must include dedusting equipment to reduce dangerous contaminants in the air. For some welding applications, fumes contain toxins such as nickel, zinc and hexavalent chromium.

Welding fume extraction systems can be source capture or hood-based. Source capture options offer flexibility and minute filtration, but workers must wear PPE. Hoods, however, can restrict visibility and mobility on the job.

Welding Fumes

Welding fume is a mixture of metal particulate generated during welding, cutting, grinding and other metalworking operations. It may contain harmful chemicals as well as gases and metal particles. These may be deposited in the nose, throat and lungs to cause irritation and can lead to serious health complications including respiratory ailments such as lung damage; emphysema; heart disease; cancer; metal fume fever; and stomach ulcers.

Exposure monitoring is key to ensuring exposure levels remain below acceptable limits, but care must be taken in sampling to ensure accurate results. Particulate matter (PM) and ozone levels are typically measured and monitored, but PM also includes volatile organic compounds such as hydrocarbons, which can be difficult to detect by monitoring. In addition to monitoring, a risk assessment must be carried out to estimate exposure and determine the steps necessary to control it if prevention is not reasonably practicable.

There are a number of options for controlling exposure to welding fumes, and the type of system chosen welding dedusting equipment depends on the layout and size of the facility, as well as the types of work that take place. For example, some systems are designed for close or point-of-source capture and can include hoods, arms that can be positioned as needed, slotted ducting, or smaller hoods for work station applications. Many offer self-cleaning mechanisms that pulse compressed air to clean the filters, extending filter life and minimizing maintenance downtime.

Welding Gases

A welder needs a variety of welding gases to complete their job. These can include shielding gases such as argon and helium, and fuel gases like acetylene, propane, butane, and others. All of these are stored in cylinders and require the use of a pressure regulator to supply them at a controlled level.

Different welding processes call for specific gases to work best. For example, pure argon works well for most TIG welding projects, while a mix of argon and C02 is great for MIG welding. Some welders may also choose to use a low amount of hydrogen in the argon to create a gas blend that improves arc stability and supports good bead characteristics.

Welding processes often produce fumes, or airborne dust particles, that can be harmful when they settle on surfaces. These particles can reduce air quality, irritate the eyes and skin, and even damage the lungs. They can also pose a fire hazard when they come in contact with electrical equipment and other materials.

Welding gas cylinders should be kept in a cool, dry area with a well-ventilated and sheltered environment. The valve of a cylinder should never be cracked where it could reach open flames, heat sources, or electricity, and it is important to only crack the valve when it is empty or when a person has the right tools to do so safely.

Welding Slag

When slag is present during welding, it can be removed using manual or power tools. These may include welding or chipping hammers, wire brushes and angle grinders with wire brush wheels or disks. It is important to remove slag from the weld to prevent it from interfering with the welding process and contaminating other parts of the workpiece.

Welding slag is formed when the arc melts the filler metal and base material to form a molten weld pool. The slag created by the melted flux helps shield the weld pool from contamination and oxidation by pushing atmospheric gases away from it. The slag also helps keep the molten weld pool in place as it cools and keeps impurities from reaching the outside of the weld area.

Various welding types, electrodes and fluxes impact how welding dedusting equipment the slag behaves during welding. For example, the slag from rutile or acid fluxes is lighter and rises to the surface of the weld pool more easily than basic slag. It is also easier to remove from weldments made with gas-shielded or self-shielded flux-cored wires than stick welding.

Poorly managed welding parameters and/or incorrect welding technique can cause the slag to become stuck to weld beads and create pockets that trap air in them. These air pockets can weaken the mechanical integrity of the weld and lead to faulty welding joints.

Explosion Risk

Welding processes produce dust that can be combustible. When this combustible dust is present in an enclosed space with a flame or ignition source, it can explode in a dangerous event known as a combustible dust explosion. These explosions can damage and destroy equipment, create a hazardous environment, and cause injury or death. They are one of the most devastating industrial accidents, but they are preventable by controlling combustible welding dust.

The size of the dust particles is important in determining their explosive potential. Fine dust particles have a greater surface area and can spread more quickly than larger, heavier granules. It is also important to consider the type of metal that is being welded. Some metals have more explosive potential than others, such as carbon steel with a Kst value of 170 (bar meters per second). Other metals, such as aluminum, have lower Kst values, but can still be explosive in an enclosed space.

In addition to combustible welding dust, there are numerous other hazards associated with welding and metal processing. Exposure to hexavalent chromium, which can be produced when welding stainless steel and other alloys containing chromium, can result in short-term upper respiratory illness. Exposure to manganese, which can be generated when welding on plated or galvanized metals, may cause neurological problems, such as headaches, exhaustion, listlessness, and weakness.