The article presents the results of a study, of the effect of basalt fiber materials on the corros1on resistance of pipe metals. The samples of basalt fibers were studied as a reason of corrosion. The tests were made according to ASTM G189 "Standard guide for laboratory simulat1on of corrosion under insulation". During the work, an experimental laboratory facility was designed to determine the corrosion rate under materials. To research the effect of the chemical composition of the samples on the corrosion process under fiber materials the influence of the leaching of chemically active anions after wetting and heating of basalt fiber were investigated. Based on the obtained results, the main factors contributing to the development of corrosion under insulation were determined, and recommendations for reduction were given. It was found that samples with open porosity showed a tower corrosion rate. The reported study was funded by RFBR according to the research project № 18-29-17068.