1. The problem statement, all variables and given/known data The strength of longitudinal joint in Fig. 1-17 is 33 kips/ft, whereas for the girth is 16 kips/ft. Calculate the maximum diameter of the cylinder tank if the internal pressure is 150 psi. - See more at: http://www.mathalino.com/reviewer/m...blem-138-pressure-vessel#sthash.G52XwZOd.dpuf 2. Relevant equations σlongitudinal = Pr / 2t 3. The attempt at a solution I have no way of calculating this since I have 2 unknowns. If you go to the link you can see the steps they've done but it doesnt make sense. Also, where does that 21600 come from?