What is the component in an immersion tank that spans the width of the tank called?

The component in an immersion tank that spans the width of the tank is referred to as a bridge. This component is crucial in the setup of immersion testing, where it supports the transducer and can be adjusted to allow scanning across the entire width of the material being tested. By using a bridge, operators can ensure consistent and repeatable measurements, which are essential for detecting flaws accurately and evaluating material integrity.

The other options, while related to structural components, do not specifically describe the part that spans the width of the tank in the context of immersion testing. Support beams provide structural integrity but are not specifically designed for movement or positioning like a bridge. Crossbars may offer support or assist in guiding equipment but are not the primary component used for spanning the width. Guide rails are typically used to permit movement along a path but do not refer to a structure spanning the tank itself. Thus, bridge is the most suitable term for the function described in the question.