Abstract
	Erosion of metals by solid particles and slury is a serious problem in many industrial applications, such as coal mining, transporatation and utilization, electrical power plant. It effects idustrial  production and development seriously.
Considering the location  of powder pipe-lines the problems of erosion wear may not be solved  from the  point of  view of  design, also not  by change of pipe-line cross-section or change of geometry of powder pipe-line bended parts. From these reasons there is a solution of excessive wear by the way of selection of materials at given composition of powdered coal. Considering the high intensity of erosion it is not possible to directly use the laboratory test results of materials for prediction of life-time of pipe-line systems. On the basis of  laboratory tests there was made a specific material selection for working tests. Selection of materials for wear conditions do not enable us in all cases to correctly interpretate the results according only by mechanical properties as strength or hardness,and toughness of material. For selection of materials in the wear conditions  the structure  of material and also the exclusion of carbide parts plays the great role. Above mentioned results are confronted with working tests in the area of straight pipe-line parts.
	In this contribution the results of working tests of exposed parts of pipe- lines are compared with laboratory measured on two types of materials applicated in thermal power plant.