Which toxic gas is produced when welding on surfaces with chlorinated hydrocarbon solvents?

When welding on surfaces that have been treated with chlorinated hydrocarbon solvents, phosgene gas is produced as a toxic byproduct. This occurs due to the thermal decomposition of these solvents under the high temperatures generated during the welding process. Phosgene is particularly dangerous; it is colorless, has a musty or hay-like odor, and can cause severe respiratory issues and other health problems upon exposure.

The formation of phosgene makes it critical for welders to ensure adequate ventilation and employ appropriate personal protective equipment (PPE) when working in such environments to minimize the risk of inhalation. Understanding the chemical reactions that occur during welding operations is essential for maintaining safety and preventing toxic gas exposure.