All vessel elevations are taken from the ______.

• A. top of steel on the embed ring (base plate)
• B. centerline of the vessel
• C. bottom of the vessel
• D. top of the vessel head

Answer: (A)

All vessel elevations are taken from the top surface of the base plate sitting on the embed ring. This provides a fixed, level reference that remains constant regardless of the vessel’s size or head type, giving a reliable datum for proper alignment with the foundation, supports, piping, and neighboring equipment. The embed ring is built into the foundation, and the base plate creates a flat, durable reference plane from which heights are measured.

Taking elevations from the centerline would change with the vessel’s dimensions, from the bottom would shift with wall thickness and supports, and from the top of the vessel head would vary with different head designs—none of which offer the same consistent reference as the top of the base plate.