The Dangers of Cutting Galvanized Steel

Cutting galvanized steel that is part of sealed compartments in certain situations can be hazardous. These situations, which arise in mines or with farming equipment, often involve cutting through steel frames, walls or other compartments filled with metal scraps. People place the scraps inside the compartments for ballast to weigh down or stabilize equipment. The zinc in galvanized steel can react with moisture from the scrap metal, creating a highly flammable stream of hydrogen that shoots out when the outer layer of galvanized steel is cut. Prevent an explosion from such a reaction by treating such cutting as if high-pressure gas is inside the compartment when you start cutting. The Centers for Disease Control and Prevention also says to use equipment specifically designed for drilling through high-pressure gas lines or, if possible, working remotely, using automated equipment. Use only dry-carbon scraps, rather than other types of metal scraps, in walls or compartments that you need to fill with ballast and install vent holes so the pressure does not build up inside the compartments.

Two examples of explosion hazards are offered in the article from CDC: Ignition Hazard From Internally-Generated H2 in Sealed Mining Equipment (see Resources). One includes workers who were drilling into a plow frame filled with scrap metal. The drilling, done in 1995 in New York State, caused a high-pressure stream of hydrogen to burst from the plow frame, knocking workers back off their feet and causing several burns.

One danger of cutting galvanized steel is metal fume fever, a condition caused by the released zinc fumes. The condition usually only lasts a single day, according to the Occupational Safety and Health Administration, with workers most susceptible after several days away from the work environment. Metal fume fever comes with a number of flu-like symptoms that include fever, weakness and fatigue, aches, nausea and chills. Coughing is another common side effect, often accompanied by a dry throat. Avoid metal fume fever by wearing protective gear that includes a mask or other protective face covering. Also, ensure your work area is well-ventilated or even outfitted with an exhaust system that sucks out detrimental fumes.

Short of causing metal fume fever, zinc chloride released while cutting galvanized steel can produce a host of other side effects. The fumes and dust irritate the skin, eyes, lungs, mucous membranes and, if large quantities are inhaled in a short period of time, can be fatal, OSHA says. OSHA has no determination on the exact quantity of fumes that are fatal. Inhaling the fumes can lead to difficulty breathing, chest pain and tightness. Zinc chloride dust on the skin often produces contact dermatitis, rashes or chemical burns. Use the same precautions to avoid other zinc side effects as you would for metal fume fever, with protective gear and a well-ventilated work area. Also, include protective gloves, long sleeves and goggles to stop the zinc dust or fumes from contacting your eyes and skin.