Shell diameter for ST-type exchanger equation

[maistral]

TL;DR

Formula for shell diameter.

Hello. I have figured out a few things about ST-type exchangers and I intend to build a reactor with this new knowledge. I have a rather... small problem.

So I searched for shell diameter correlations given the pitch and number of tubes and I found this from a writeup:

Apparently, it's from Ludwig, but the writeup did not say where the equation is, exactly. I have been staring and scanning at Ludwig for five long hours now and I am unable to find this equation (lol, I swear my eye nerves are going to burst). Is someone familiar with this equation? Thank you.

 

[maistral]

Nevermind, found it. Apparently it's in another Ludwig book. Applied Process Design for Chemical and Petrochemical Plants; eqn 10-2; for people who might need this.