What is the temperature at which base risers should be removed during the welding process?

The appropriate temperature for removing base risers during the thermite welding process is approximately 900 degrees Fahrenheit. This temperature is critical as it ensures that the weld metal has sufficiently cooled and solidified, allowing for the safe removal of the risers without compromising the integrity of the weld.

Thermite welding involves a chemical reaction that generates an extremely high temperature—typically around 4500 degrees Fahrenheit—that melts the metal. After the welding process is completed, the weld needs to cool down to a level where it can withstand handling without affecting its structural properties. At 900 degrees, the weld is cooled enough to maintain its strength and stability, while still being workable enough to allow for the safe removal of the base risers.

Each of the other temperatures listed would either be too low, risking structural integrity by allowing the weld to still be too soft, or too high, increasing the chance of damaging the weld and surrounding material during removal. Thus, the choice of 900 degrees is based on maximizing safety and preserving the quality of the weld.