Nozzle Reinforcement

I’m designing a pressure vessel on saddle supports with nozzle at shell and heads. The nozzle is located at knuckle region of the torispherical head. I´ve calculated the nozzle geometry and it doesn´t need a reinforcement. But my question is: Is there a section on the code that suggests nozzle reinforcement when it is located at knuckle region of the head?


The knuckle region of a vessel is highly stressed and placing a nozzle in that region is not recommended. In fact PD5500 does not allow a nozzle to be placed within the knuckle region and specifies a distance within which a nozzle is not allowed.

Above is a snippet.