I have to design a Nozzle. When I run the program I got this message “Rn/R ratio exceeds 0.7 so a U-2(g) analysis is required - see Appendix 1-7(c)” . On the code, U-2(g) and 1-7-© are not clear explained

How can handle this message??

Vessel with ID=15.25 in and Nozzle ID= 12 in

Thanks

Alvaro

Alvaro,

As per the code clause UG 36 (b), supplimental rule 1-7 (rules for large opening) are to be followed if the opening dia is more than 1/2 of vessel dia or 500 mm for vessel dia upto 1500 mm.

For vessel dia larger than 1500 mm, supplimental rule 1-7 to be followed if opening dia is more than 1/3 of vessel dia or 1000 mm.

As per 1-7, 2/3 the required reinforcement is to be provided within the limits specified in the section.

Generally computer softwars use 1-7 rule if opening falls under large opening. Which softward you are using for calculation, check if there is any option for considering large opening if it does not select by default.

Can you use a standard 16" x 12 " reducing Tee, probably it will be much easy for fabrication and also for calculation.

Regards

Hi Alvaro,
Read 1-7(b)(2) and the following (3) and (4). Did you try on your computer to enter thicker vessel shell or reinforcing pad? (the extra reinforcement in this case is not for compensation but to sustain additional membrane and bending stresses. The reference to 1-7(c) calls to special examinations in case of large openings. U-2(g) requires other calculations and analysis when no design rules are provided in Sect.VIII Div.1. for the required detail. mauro