Is aluminum welding toxic?

Posted by Jörg Reips on Sep 13, 2021 12:14:47 PM

When welding aluminum, as with all other weldable metals and metal alloys, emissions arise in the form of combustion and evaporation residues.

Which protective measures are suitable here and is aluminum welding toxic?

Emissions from welding aluminum

Arc welding produces both gases and particles, which are collectively referred to as welding fumes. When welding aluminum, the material transition from the filler material to the base material mainly produces what is known as aluminum oxide, which can be found in the form of particles in the welding fumes. These particles can range in size from 10 to 400 nanometers, depending on the welding process used.

The size of the particles determines how far they are inhaled and whether they can penetrate into the alveoli, and accumulate there.

All particles suspended in the air that can be absorbed via the respiratory tract are part of the inhalable dust fraction, also known as E dust. The smaller particles of this E fraction also make it into the alveoli, therefore they are referred to as alveolar dust fraction or A dust.

Due to their small size (0.001 mm), the particles in the welding fumes are classified as A dust and cannot be easily removed from the body by the self-cleaning system of the lungs.

Inhalable and alveolar dust fraction

(Source: Graphic based on BGHM)

When welding aluminum, inhaling these particles in the form of aluminum oxide, if excessive, can lead to respiratory and lung diseases, often in the form of bronchitis. Aluminum oxide is classified as a hazardous substance that pollutes the lungs during welding and, in the worst case, can lead to aluminosis, the aluminum dust lung. Aluminosis is incurable and one of the occupational diseases that are subject to compensation.

Whether aluminum welding is toxic and what damage actually occurs depends mainly on the intensity and less on the duration of exposure to the aluminum oxide, which is harmful to the lungs. The risk from metal oxides is assessed using the general dust limit value, which therefore also applies to aluminum oxide (Technical rules for hazardous substances: TRGS 900 “Occupational Exposure Limits”).

Another emission that occurs when welding aluminum is the gas ozone.

Ozone is created under the influence of UV radiation and oxygen. During inert gas welding, the arc produces UV radiation. Bare surfaces such as aluminum intensify their reflection, which leads to an increased formation of ozone. Paradoxically, rising welding fumes hinder the formation of ozone, as there are fewer reflections.

The preferred welding methods for welding aluminum are MIG welding or TIG welding. These two processes generally produce less welding fumes than MAG welding, so that the emergence of ozone is intensified by the low fume development.

When welding aluminum, ozone is therefore often produced in higher concentrations. According to TRGS 905 (Technical Rules for Hazardous Substances: TRGS 905 “List of carcinogenic, germ cell mutagenic or reproductive toxic substances”), ozone is classified as a toxic, carcinogenic gas. However, some of the unstable ozone breaks down again to form oxygen in the area of welding fume emissions, so that critical limits usually are not reached.

Therefore, if you ask yourself whether aluminum welding is toxic, you should note that in addition to aluminum oxide, which is harmful to the lungs, welding fumes also produce a highly dangerous gas such as ozone.

Aluminum emissions in any case should be extracted from the work environment directly at the point of origin with suitable mobile or stationary fume extraction systems - ideally in combination with fume extraction torches.

Protective measures when welding aluminum

When welding aluminum - as with all other welding processes - toxic welding fumes should not be inhaled during welding. The closer the fume extraction is to the process, the better the welder himself and all colleagues in the production hall are protected from harmful particles and gases in the welding fumes, as the welding fumes cannot then get into the ambient air.

The most effective method is the use of fume extraction torches in combination with fume extraction systems, as the particles are extracted directly at the source. An effectiveness of up to 95% can be achieved here.

Fume extraction torches are available in almost all performance ranges for MIG/MAG applications and for TIG applications.

Central ventilation and extraction systems, which are usually far away from the source where the toxic welding fumes originate, only offer inadequate protection, as the emissions are inhaled by the welder before they can be extracted.

The figure shows the various extraction technologies, labeled with typical parameters such as distances and required suction volumes:

Extraction technologies with typical parameters

If you want to extract toxic welding fumes efficiently and if you are looking for the best possible protection for your welders, you are definitely on the safe side when you choose a fume extraction torch.

In conclusion: When welding aluminum, toxic welding fumes are produced and the question of whether aluminum welding is toxic can therefore be answered with a definitive “Yes”.

 

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Topics: Fume Extraction