Providing loops alone on the pipe rack does not give stress engineer to control the pipe thermal expansion. You should also provide adequate line stoppers or anchor type supports between or ends of loops, restraints somehow depending on the pipe arrangement. Entire pipe under the thermal/seismic load will float on the rack if it does not see adequate resistance axially and laterally, and you will see all the shoes will leave the structural supports unfortunately.

If the case as I explained above you do not have any guaranty on the stresses on the piping. If all the supports moved off the supports the problems may be concentrated at the beginning and end of the rack on the piping. If some stays on shoes , some still on the supports the problem is more complicated which depend on the on/off support locations. If you are lucky and very large gap between allowable and analysis stresses it may still work up to until the planned shotdown, but there is no guaranty for creep, stress, strain and integrity of the piping. I would not rely of it at all and get prepared to replace the section under consideration. If you decide to continue to operate take all the precautions by assuming it will fail any time soon where the stresses are more concentrated. I believe you do not have time to get real stresses by analysis since this will take a long time if the problem gets more complicated, and the results may not be satisfactory either. However you'd better get everything documented, prepare markups on the isometrics for thermally expanded and new locations of the off-support shoes ASAP to make decision.

If the lateral supports (guides) are connected by design onto the shoes the lateral supporting action may not be there anymore, so problems are more complicated for modelling on the pipe as it is.

I would not make the decision myself, advice the management for the problems and make decision all together and document.

Good luck.