Galvanized Steel
The process of welding galvanized steel is commonly found in the metal fabricating industry. Many welders usually weld galvanized steel at some point in their career; and in doing so they may experience galvanize poisoning or metal fume fever. Galvanize poisoning is a condition that results from the over exposure to zinc oxide. Zinc oxide forms when the steel’s galvanized coating evaporates from the high heat used in welding.
Galvanized steel is iron with a coating of zinc. When the galvanized steel is hot-dipped the zinc has a chemical reaction with the base metal and forms a corrosion resistant coating. This results in the outer layer of the metal have a coating of pure zinc while subsequent layers change in composition until you reach the iron base metal. In the outer layer and iron base metal, zinc oxide can be found in different percentages of zinc to iron. The zinc oxide that is found on galvanized steel shares the same chemical attributes as the white powder that is used by lifeguards to protect their noses from becoming sunburned.
Proper Preparation
Whenever you are working with galvanized steel it is important that you take the necessary steps when prepping the metal before welding. If you have properly prepped your metal before welding, you will help reduce your exposure to zinc oxide fumes. While prepping the base metal will remove the majority of the zinc from the surface of the metal, the possibility of some galvanizing while welding may occur. A common sign of galvanizing is the appearance of yellowish-green smoke. Other signs are a white powdery particles in the air, and a white residue around the weld. If exposure to large quantities of the yellowish-green zinc oxide fumes occur, you may experience galvanize poisoning, or metal fume fever as it is sometimes called. The severity of your symptoms depends on the amount of time of exposure to the harmful fumes.
Galvanize Poisoning
Symptoms of galvanize poisoning can be similar to flu symptoms. The onset of symptoms typically begin shortly after exposure to zinc oxide and may include a mild headache and nausea. If you have a more severe case of exposure, your symptoms will be consistent to those you experience when you have the flu. A moderate case of exposure will result in symptoms including chills, shaking, a slight fever, vomiting and cold sweats. If you begin to experience any of these symptoms you should immediately stop working and get some fresh air. In severe cases the symptoms may be so bad that you will have to go home until they subside. The most severe cases of galvanize poisoning can result in death. If you feel that your symptoms are worse than ever before, you should seek medical attention at once.
Galvanize poisoning is often short and your symptoms should begin to lessen within four hours of exposure. You should be completely symptom free within twenty four hours. If you experience a stronger exposure, you may still be experiencing symptoms up to forty-eight hours later. We recommend upon exposure that you drink milk in order to quicken your recovery. The calcium in milk helps remove the zinc build-up from your body.
How To Avoid
To avoid overexposure to galvanize fumes, you should have proper ventilation and avoid direct contact with zinc oxide fumes. Welders who have many years of experience also recommend drinking milk before, during and after welding galvanized steel to lessen your risk of galvanize poisoning. You may also want to purchase a welding hood fit for welding galvanized steel.
Resources for Welding Galvanized Steel
- Avoiding “Fume Fever” (blog article)
- Respiratory Protection (BakersGas.com welding supplies)
- Fume Extraction Equipment (BakersGas.com welding supplies)
Proper Respiratory Protection
When welding around any fumes you should consider wearing a welding respirator. Either a welding specific option or a full PAPR system.
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