Hello klchong

Firstly, let us look at UG-36(c)(3)(a). The nozzle has in inside diameter of 77,93 mm. The head thickness is 12 mm. According to the paragraph you do not have exemption. I am not sure why you got the exemption. When I ran the calculation, the reinforcement calculation was performed.

Perhaps you could send me the file, and I can have a look at it.