The sketch isn’t a good design, but I’ll entertain it - the answer is you need to account for some, but not all. You do need to estimate deflection due to gaps in the thread, and some deflection of the thread. (This gives you deflection - you calculate the loss in preload force by F=kx; your...
a greybeard i work with is telling me to research the taskline gasket as he's never seen one fail by blowout. does anyone have any experience? we switched most of our plant over to cut eptfe sheet w/ fillers. this was before my time.
fyi taskline gasket is molded ptfe but has a perforated...