Understanding welding fumes

WITH the correct PPE, arc welding mild steel in an outside area, or in a well ventilated workshop, is not a problem, but when welding more exotic materials that's when fabricators and co-workers should take special care.

Arc welding fumes contain very small particles from the consumables base metal and base metal coating.

The substances in the fumes change depending on what is in the electrode and the base metal including any coatings.

The most common compounds in the fumes when welding mild steel, for example, are complex oxides of iron, manganese and silicon.

The short term effects of these compounds, if inhaled, are temporary and include burning eyes and skin, dizziness, nausea and fever.

However long term exposure to these fumes can lead to silicosis (iron deposits of the lungs), bronchitis, and even lung fibrosis has been reported.

And if the compounds found in the welding fumes includes Barium, symptoms may include severe stomach pains, slow pulse rate, convulsions, muscular spasms and even death.

Welding equipment manufacturers and industry organisations highlight the need for fabricators, and their co-workers, to be especially careful when working with new metals and materials, particularly when welding heavy metals such as magnesium and chromium. 

Welding proffesionals should understand that it all depends on the base material and the consumable the welder is using and if the metal is coated. It is not uncommon for welders to be overcome with paint fumes when welding painted metal.

Thankfully, most welders are aware of the dangers of welding fumes, and the short term and long term respiratory problems they can cause.

For example the vast majority of welding machines and consumables in Australia have warning labels on them regarding welding fumes.

However, welders should be especially aware of working with exotic materials such as cadmium, chromium, cobalt, copper, fluorides, manganese, nickel, silica and zinc, even stainless steel.

Fumes from the following metals can cause:

CADMIUM requires extra precautions, especially as it is often found on steel and steel fasteners as a plating or in silver solder. Cadmium fumes can be fatal, even after brief over-exposure.

CHROMIUM poses a cancer risk. Stainless steel and other hard coatings contains chromium and can cause lung cancer and asthma.

COBALT may cause respiratory diseases and pulmonary sensitising, and in metallic form it has been know to cause lung damage.

COPPER may cause metal fume fever, skin irritation and discolouration of the skin and hair.

MAGNESIUM may affect the central nervous system, difficulty in speaking, and arm and leg tremors, often non-reversible.

NICKEL may cause cancer.

SILICA may cause silicosis.

ZINC, found in galvanising, may cause fume fever.

Sasanka Sinha, Technical Manager with WTIA (Welding Technology Institute of Australia) says most welders are aware of the need to wear some form of PPE (Personal Protective Equipment) when welding, "but it's not always obvious how dangerous these fumes actually are when welding different materials.

"Problems can arise when welders take on a new job or a new material to be welded. Sometimes they are not aware what the fumes contain, especially with Stainless Steel.

"Galvanised or coated materials can also cause problems, it depends on the thickness of the zinc used when galvanising.

"If the thickness of the galvanising changes from thin to thick, without the welder being aware, that can cause problems," Sinha told Manufacturers' Monthly.

Protection from fumes

Sinha's advice for welders is to use their common sense.

"In Australia, welders are very good, they know their job and are aware of the dangers of welding fumes. They know what PPEs they must use.

"It's the responsibilty of management to make sure they wear the correct PPE.

"Some welding helmets, for example, have there own extractor, so the dangerous welding fumes can be extracted right at the welding arc.

"And if the welder is operating inside a confined space such as in a tank, boiler, or pressure vessel, it is the responsibility of the supervisor to provide fresh air and extraction.

"It is also mandatory the welder has a 'fire-watcher' outside to ensure the welder is not overcome by fumes," Sinha said.

However, most welders know that wherever they are they should wear PPEs such as breather masks and use some form of ventilation.

The first option is to ventilate the whole environment. This could take the form of open windows and doors in the workshop so they get cross ventilation.

Then there are fans and suction devices that manufacturers can use, through to fume extraction arms and hoods, and downdraft tables through to fully engineered systems.

The key is to get the point of extraction as close as possible to where the welder is operating.

The goal is for the welder not to breathe any welding fumes at all, so manufacturers should remove as many of the fumes from the workplace as possible. 

There are a wide range of options available, depending on the location and the metals being welded.