Hi deepskysea
I think it should be ok mechanically pressure wise, as long as the vessel is sturdy i.e. it does not expand or move about (like a balloon) on pressurisation
placing undue stress on coating.
I assume the main function of the coating is corrosion resistance. My concern would be for quality and choice of coating. Obviously, coating needs to be resistant to vessel contents, but probably more important, it needs to be a 100% effective barrier. At high pressure there will be more driving force for the environment to find its way through the coating (on initial pressure-ups anyway), so coating density and sealing are very important factors to consider.