I suggest that you become very familiar with API RP686 very quickly. This RP will assist your questioning as to the status of the equipment and piping prior to start up. Did you analyze what was built? Did they build what you analyzed? Was a check list used by operations prior to startup? Was a stress engineer present or was the system reviewed by a stress engineer?

There are many analysts who consider friction for the same reasons that you did (rationalized the effects of friction.) It certainly makes the stress analysis easier and at least the analysts relationship with the piping designers doesn't suffer. I consider friction in my analysis and it does result in "technical discussions" with others.

Friction has varying effects on piping and greater effects on equipment loading. That probably gives fuel to the analyst that minimizes friction on piping because his experience hasn't indicated major problems. How many large turbine and compressor combinations has the average analyst reviewed. In a life time, the number isn't that high. The more I read, the more I'm convinced that one should consider factors that effect the analysis.

I didn't see any information about the compressor, but the displacement of the compressor side of the coupling relative to the turbine side should have been considered. Again the API RP will add years of experience to your analysis. Learn the contents of the alignment section. Read the checklists, and ask if they were followed.

The problem resolution could come from something as simple as jack screws and equipment feet interference or a tack weld not removed from a support that was supposed to slide.

Somebody missed something (obviously) and the stress engineer is the primary target because we know that the calculation can't change as fast as a spring stop can be removed.

The percentage exceeding the allowable would most likely be accepted by the equipment manufacturer prior to contract.

I bet that next time you use friction and give the loads to the manufacturer even if you find the problem was due to travel stops not being removed.