May I ask what the difference between the two circles is?

Reinforcing rings specifically refer to structures designed to enhance strength, while Stiffening rings are used to increase stiffness. Essentially, both refer to rings that serve to strengthen something, though there are slight differences in their characteristics

Stiffening rings are used to reinforce pressure vessels at the locations where openings are made, in order to address the stress concentration resulting from those openings. Simply put, less material is available at the area where the hole is made, which means the material in the areas surrounding the hole is subjected to greater stress. Generally, the area of the reinforcement ring is equal to the area of the opening. Adding reinforcement rings and increasing the wall thickness of the container are two methods to enhance the stiffness of the container and raise its critical pressure under external pressure. In particular, it is more economical to appropriately add reinforcement rings to the cylinder of a container under external pressure. When designing reinforcement rings, the most basic requirement is that their actual moment of inertia be greater than the minimum moment of inertia. It can be fabricated using angles, I-beams, rectangular steel, etc., and can be welded to the outside or inside of the container. When the reinforcement ring is welded to the outside of the cylinder, the total length of the intermittent welds on each side of the reinforcement ring shall be not less than 1/2 of the outer perimeter length of the container ； When installed inside the container, it should be at least 1/3 of the inner circumference length of the container.

I believe that reinforsing rings and stiffening rongs are the same thing.

Discontinuities in each side weld? If it’s a circle, why are there intermittent welds? Please give me some advice.