If the vessel has slots in its baseplate, the vessel design engineer obviously expects it to be able to slide and it probably will. Since you mention grout, I will assume that the vessel support is a concrete column or pedestal of some kind. The vessel designer has given a friction load of 52 something, is it kN, is it KIPS, tonns, what? Anyway, it looks like they have taken a friction factor of 0.3, which is a typical; friction factor for steel contacting steel and for steel contacting concrete, because 173 x 0.3 = 52. What you need to do is ask your structural/support engineer if he can design his support to take a load of 52. If it can and it is a concrete pedestal or column support then that support should be provided with a steel plate that is embedded into the grout, so allowing for a sliding contact between support and vessel. A steel plate embedded in the grout usually helps to prevent the frictional force from damaging the edges of the concrete from localized shear, and it is customary to provide one. If 52 is too high a load for the support, then a teflon, micarta or other friction reducing material might be used between the plates to attempt a reduction in frictional load transferred to the pedestal. I also note that this vessel is in an earthquake zone and the earthquake load is double the thermal frictional load, so it is most likely that earthquake load will control the structural design, at least that appears to be true for the pedestal under the fixed support. Get things straight with the structural engineer and proceed accordingly.
“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"
