Stiffener Ring

OK. How about some context here? Otherwise the possible answers range through:

• Because the designer omitted it deliberately, to
• Because the designer omitted it unknowingly

This is not true at all, the using of stiffener ring is avoided only in specific situations such as in equipment under cyclic service, only by doing mention of one case. The stiffener rings are of common using for equipment in which design conditions include vaccum service or steam out, often the using of these rings include significant saves in the material, doing mention too that they can be used as isolation rings. By the before said is not a absolute true avoid these elements in the design and fabrication of pressure vessels.