Welding of Stainless Steels - dangers and safety

The article discusses the common risks associated with stainless steel welding and ways to ways to mitigate them. It is very important, both for employer and employee, to have accurate knowledge regarding these matters.

Welding of any steel is dangerous due to various factors, such as:

• Electromagnetic field
• Harmful gases and fumes
• Radiation
• Noise
• High temperature
   

However stainless steel welding poses additional risks related to large chromium and nickel content, commonly present in stainless steel.

Electromagnetic field

The intense electromagnetic field accompanying the welding process is a factor worth recognizing when welding is the primary occupation of the worker.

Ways to protect

The electromagnetic field dissipates, so proper way of lowering the risk is to mark sources of the field and possibly keep them on a distance from the welder.

Another way is to incorporate pulse welding, which reduces the field.

Welding fumes and gases

Welding produces harmful fumes and gases. Welding fumes can be observed with a naked eye, while gases can not.

Fumes produced during welding stainless steel are particularly dangerous because they contain chromium and nickel compounds. Moreover, welding fumes can remain in the air for a long time and easily reach and affect the welder.

Hexavalent chromium compounds present in welding fumes are carcinogenic and cause changes id kidneys and respiratory system. Chromium (VI) compounds, which are either carcinogenic and are considered as such are:

• Chromium (VI) oxide
• Chromium trioxide
• Chromium dioxide
• Potassium dichromate (VI)
• Potassium chromate (VI)
• Sodium dichromate
• Sodium chromate
   

Nickel compounds are carcinogenic and cause changes in the respiratory system, which may result in fibrosis, asthma and lung cancer or nose cancer. Nickel compounds present in stainless steel welding fumes with a proven carcinogenic effect:

• Nickel oxide (II)
• Nickel oxide (VI)
• Nickel trioxide
   

Ways to protect

First of all, choose proper shielding gas. The highest fume emissions occur with pure argon shield gas and argon-carbon dioxide gas, thus a mixture of argon and oxygen (without carbon dioxide) is recommended.

Secondly, if only possible, use welding fumes extractor or a fan. Mobile units can be quickly set up on a spot and make the job much safer.

Means of respiratory protection can also be used.

In GMAW welding, the welding current and the nature of metal transfer also affect the emission of the fumes. Spray arc welding creates more than twice as much fumes as short circuit welding.

Welding radiation

The welding arcs emits radiation over a broad range of wavelengths, from infrared radiation, through the whole spectrum of visible light to ultraviolet radiation. Combined, they deal great damage to the sight, but also affect the skin, possibly resulting in:

• Cataract
• Eye inflammation
• Retina changes (for example retinal detachment)
• Skin burns
• Skin lesions or cancers
   

Personal protective equipment is an absolute must. Be equipped with protective clothing and a welding helmet.

Noise

Welding produces much noise. It should not exceed the following values:

• 85 dB - average exposure level
• 115 dB - max noise
• 135 dB - pitch
   

When noise exceeds 80 dB, the employees must be equipped with earplugs or hearing protectors.

Electric shock

An electric shock can occur because of defective equipment or insufficient protection. Welding inside tight objects, like pipes or tanks, increases the risk of an electric shock.

Ways to protect

Make sure protective clothing and footwear are in proper condition. Wet or dirty clothing, punctured shoes or damp floor increase the risk. Use protective mats to galvanically separate.

When welding in special conditions, special health and safety regulations must be observed.