Guys thanks for the replies. I will proceed with the bilinear.

Hi John - thanks, it took me awhile to get here. I have been playing process engineer as of late, and am just now getting back to more mechanical and piping. Well, at least it all pays the same. :-) Thanks for the great insights on the slip joints; I passed them along to our structural guy for his use in design of the anchors.
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Thanks!
Pete