Thank you, Michael for the response.

I agree with you in practical sense with everything you say. But alas, ASCE-7 is adopted as law in most states I can think of. And the code doesn't differentiate the requirement for piping flexibility at piping to tank & vessel connections depending on seismic zone. I'm looking for get out of specification hell cards left and right!

I tend to think the "Unless otherwise calculated, the minimum displacements in Table 15.7-1 shall be assumed." as not a way out, but as a way to actually increase the displacements if additional info is available (like a soils report). Piping to nozzle connection displacements differs from calculated accelerations. The accelerations would apply to ASCE-7 section 13 for piping, right? Calculating seismic movement in equipment is a specialty and not sure I've seen anything except a settlement value given leaving the other 5 directions left to be pulled from the table. I have no issues running seismic analysis per section 13 with accelerations in my models. Section 15 is specific to the piping to equipment connection and the movement created in the piping as a result. As you seem to also be aware, some of these displacements are enormous and every facility I've ever seen obviously appears to be completely designed without applying the requirements of Table 15.7-1. Which I totally understand. It is generally not feasible, economical, nor practical to design every single connection to a vessel or tank to these measures. Hence, my question since it is considered law. So I'm curious how others in the industry view this topic.

By the way, UTS = Ultimate Strength I presume? Again, thank you!