Nozzle - The Appendix 1-7(b) Rn over R ratio

Lasted Updated: 2022.10

First Published: 2020.6

The 2021 release of Appendix 1-7(b) in Section VIII, Division 1 changed the previous understanding (see below) about the Rn/R ratio. Now a warning will appear whenever the ratio is exceeded, for years 2021 or later.

Previous understanding and behavior for code years 2019 and earlier:

Confusion in the past has been from a misinterpretation of this section of the code. The misinterpretation is that if the ratio is exceeded, the requirement for U-2(g) applies in all cases. This is not true. The requirement for U-2(g) only applies if the ratio is exceeded and1-7(b)(1)(a) and (b) are true. See interpretation VIII-I-98-83