Vessel parts are weakened when material is removed to provide nozzle openings. The stress concentration is high at the edge of the opening and decreases with distance from it becoming negligible beyond twice the diameter of the opening. These openings require compensation or reinforcement to avoid vessel failure in those regions due to high stress concentration. This can be done either by increasing the entire shell thickness, or by using a self-reinforcing nozzle. This paper is concerned with the CAD of reinforcing nozzle.