1.7 Stiffeners

  • Vertical vessels may be stiffened by the addition of internal or external members attached in either the longitudinal or circumferential direction, and in some cases in both direction.

  • Reinforcement of top-course of shell for large open tanks

    • Open vessels of large diameter may not have the necessary inherent rigidity to withstand wind loads without deforming and excessively deforming the structure.

    • Two methods of stiffening are available: shell plates may be made thicker, or suitable stiffening girders may be added to the structure. The use of thicker shell plates usually is more costly than the use of stiffening girders. The stiffening ring is placed preferably on the outside of the shell rather than the inside. Structural steel can be used for stiffeners.

    • If the tanks are closed with a roof, the roof provides additional structural rigidity to the upper course of shell plates. As a result, smaller stiffening rings are used for closed vessels.