When inserting the lit igniter, to what depth should it be placed into the weld charge?

In thermite welding, the depth at which the lit igniter is placed into the weld charge is crucial for ensuring the proper initiation of the reaction. Placing the igniter one inch into the weld charge is optimal because it allows for sufficient heat and energy transfer to the thermite mixture, which is necessary to trigger the exothermic reaction effectively.

If the igniter is inserted too shallow, it may not generate enough heat to initiate the reaction, leading to an incomplete weld or failure to weld at all. Conversely, if it is placed too deep, it may not effectively transfer the ignition energy to the thermite, creating a risk of insufficient combustion or delayed reactions.

Thus, one inch strikes the right balance, ensuring effective ignition while minimizing risks associated with improper placement.