Thickness and Reinforcement Calculation of Cone With Knucle and Flare

I am currently making thickness and reinforcement calculation for cone (with knuckle and flare) due to EXTERNAL pressure using ASME Sec. VIII div. 1.

I will be using this calc. sheet in preparing engineering drawing. My problems are the following:

1. Reinforcement calculation Appendix 1-8

It is clearly specified in Fig. UG-28.1 Note (1) that if knuckle is provided, it is no need to do reinforcement calculation using Appendix 1-8 however, Note (3) requires the Moment of inertia to be check using appendix 1-8.

What I do not understand is that in Appendix 1-8 the formula used to determine Lc, ATL and ATS are for cone without knuckle only, I think there is no consideration of Knuckle or flare in the equation. Of course I will follow the ASME equation in my calculation, I'm just curious.

2. Thickness calculation UG-33

The equation of unsupported length (Le ) are given in UG-33(g), there are 4 equations.

My concern is on the equation 2 and 4. The unsupported length (Le) is determined in terms of DLs however, the factor used in external pressure calculation is DL / Le. I don't have problems on equation 1 and 3 since (Le) is determined in terms of DL.

I've been working on pressure vessel design for almost 5 years but this is my first time to design a cone with knuckle and flare.

I have a little knowledge in ASME standard that's why I am asking if anyone can help me on this.

Also sorry for my poor English.