What is the required minimum preheat and interpass temperature for 1" thick API 5L Grade B steel welded with flux-cored arc welding?

The minimum preheat and interpass temperature for welding 1" thick API 5L Grade B steel using flux-cored arc welding is crucial for ensuring proper weld quality and preventing issues such as cracking. Setting the temperature at 50°F is aligned with industry standards for this type of material and thickness, as it helps mitigate the risk of hydrogen-induced cracking in the weld.

Preheating the steel before initiating the weld allows for better absorption of heat into the base material, facilitating penetration and fusion during the welding process. It also minimizes thermal stress as the heat from the welding process is less likely to cool the base material too rapidly, which helps maintain the integrity of the weld.

While lower temperatures are acceptable in some cases, they may not be sufficient to ensure the desired metallurgical properties for thicker sections of API 5L Grade B steel. Therefore, the choice of 50°F is appropriate as it sits safely within the range required for effective welding while also addressing concerns regarding the heat treatment of the base material during the welding process.