The process of welding galvanized steel is commonly found in the metal fabricating industry. Many welders will be required to 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 is formed when the steel’s galvanized coating evaporates from the high heat used in welding.
Galvanized steel is iron that has been coated with 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 the iron base metal is reached. 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.
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, white powdery particles in the air, and a white residue around the weld. If you are exposed to large quantities of the yellowish-green zinc oxide fumes, 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 that you were directly exposed to the harmful fumes.
Symptoms of galvanize poisoning can be similar to flu symptoms. The onset of symptoms typically begin shortly after you have been exposed to zinc oxide and may include a mild headache accompanied by nausea. If you have a more severe case of exposure, your symptoms will be consistent to those experienced 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 anything you may have experienced you should seek medical attention at once.
Galvanize poisoning is often short-lived and your symptoms should begin to lessen within four hours of exposure. You should be completely symptom free within twenty four hours. If you experienced a stronger exposure, you may still be experiencing symptoms up to forty-eight hours later. It is recommended that once you have been exposed that you drink milk in order to quicken your recovery. The calcium in milk helps remove the zinc build-up from your body.
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 that has been specifically designed for use in welding galvanized steel.
Picture Source: www.thefabricator.com
Resources for Welding Galvanized Steel
- Avoiding "Fume Fever" (blog article)
- Air Purifying Respirators (BakersGas.com welding supplies)
- Fume Extraction Equipment (BakersGas.com welding supplies)