Boilers are widely used in various fields of industry, specially in wood processing sector as the heating supply to wood drying process. In this article, the author presented methods of operation, criterions for assessment of the welding quality. The experimental research was carried out basing on the methods in plan of multifactor and singlefactor experiments. As the result, mathematical model was created which displayed individual influences and simultaneous influences of factors in different welding recommendations to criterions for assessment of the welding quality such as longitudinal strength, bending strength, impact strength. These results were foundation for problem-solving in mathematical optimization to define the optimum values of parameters for wood - drying boilers welding. This seems tobe a database creation for the automated process in welding boilers or using robots as a programmed equipment which might be a tremendous achievement in the boilers manufaturing process.