Final answer:
The space between plates in a square butt joint is called the Root opening, which refers to the distance between the plates at the joint root. The root opening affects the strength and integrity of the joint.
Step-by-step explanation:
The space between plates in a square butt joint is called the Root opening. It refers to the distance between the plates at the joint root. The root opening affects the strength and integrity of the joint, as it determines the amount of filler metal that can be added during welding.
For example, if the root opening is too large, it may result in insufficient penetration and a weak joint. On the other hand, if the root opening is too small, it may lead to excessive heat and distortion.
Therefore, it is crucial to have the correct root opening to ensure a strong and durable square butt joint.