At what ambient temperature is welding prohibited?

Welding is prohibited at ambient temperatures below 0°F due to the increased risk of various issues, such as poor fusion and incomplete penetration of welds in the material. At such low temperatures, the metal can become brittle, and the properties of the steel can be adversely affected, resulting in potential structural weaknesses and failures. When welding at extremely low temperatures, the heat from the weld can raise the temperature of the surrounding metal quickly, leading to thermal stress and potentially causing cracks or distorting the material.

Preventing welding in these conditions helps ensure that the quality and integrity of the weld are maintained, following the guidelines set forth in the AWS D1.1 code. Therefore, AWS specifies this temperature threshold to prioritize safety and the performance of weldments in service.