Calculating preload and pull-out strength for ANSI B1.9 Buttress thread connections?

[cbrf23]

How does one go about calculating the preload and pull-out strength for a buttress threaded connection?
In case it's unclear, this is a mechanical non-sealing (ANSI, not API) buttress thread. The intended application is attachment of a hydraulic cylinder to a base for a hydraulic press.
I'm quite familiar with calculations for 60° UN threads, but I can't find anything online or in the machinery's handbook relative to calculating preload, proof-load, pull-out strength, etc. for buttress threads.

For reference here are the calculations I use for UN threads:
Length of Engagement:
Le= 2At / (3.1416Knmax[1/2+0.57735n(Exmin-Knmax)])

Tensile-stress area for steels with UTS > 180ksi:
At= 3.1416(Esmin/2 - .16238/n)^2

Tensile-stress area for steels with UTS ≤ 180ksi:
At= .7854(D-.9743/n)^2

Load to break threaded area
P= S*At

Definitions:
Le=Length of Engagement
n=number of threads per inch
Knmax=maximum minor diameter of internal thread
Esmin=minimum pitch diameter of external thread for thread class
At=tensile-stress area of screw thread
D=basic major diameter of thread
P=load (in lbs) to break threaded portion of component
S=UTS of threaded component (in PSI)



Because I had to open it to pull out my calculations, attached to this post is handy spreadsheet I made for UN calculations; think of it as a pre-reward for helping me with this question

Thanks!!

 

[CoryPad]

API RP 5C1 Recommended Practice for Care and Use of Casing and Tubing has one treatment for stress in buttress threads.

 

[cbrf23]

@CoryPad - I don't have a copy of that spec, can you tell mi if it provides pull-out strength calculations and/or pre-tension calculations? Is there a size range it covers?

Thanks!