What tool is primarily used to check for buckling in support columns?

The primary tool used to check for buckling in support columns is the plumb line. A plumb line provides a vertical reference point, making it easier to visually assess whether a column is perfectly upright. When a support column is subject to buckling, its alignment can shift, resulting in a deviation from the vertical line of gravity. Using a plumb line, inspectors can quickly identify any misalignments that indicate potential structural issues.

The accuracy and simplicity of the plumb line make it an effective choice for this specific inspection task, as it allows for direct observation of verticality without the complications that other tools might introduce in this scenario. This makes it particularly useful in determining if the columns are structurally sound and functioning as intended in maintaining the stability of the pressure vessel or any system relying on that support.