Sintered protective coatings are a proven technical solution against corrosion and erosion of tubes in biomass- and waste-fired boilers. The main field of application are tubes like superheater tubes or heat exchanger tubes in fluidized-bed installations corrosion endangered by the flue-gas stream. These sintered solutions complete other thermally sprayed coatings in those critical cases, where gas-dense overlays are needed due to corrosive damage. In those cases, where oxidation and erosion dominates, thermal spraying without sintering is remaining as primary solution. The development of Twin coatings out of sintered and non-sintered thermally sprayed alloys is showing a new and interesting alternative for tubes exposed to erosive-corrosive stresses under high temperature conditions.