The advantages of metal silos in comparison with reinforced concrete are given. Types of silos depending on a wall design are considered. The construction of steel spiral-fold silos and the method of forming a cylindrical body are considered. The general design of a spiral-fold silo is illustrated. Features of the folding lock, its geometry and location are described. The specifics of the construction of spiral-fold silo, which affects their stress-strain state, are analyzed. Listed two calculation schemes of silо depending on the complexity of input information for the computer. The standard documents which regulates the design of steel silo tanks on the territory of Ukraine are analyzed. The main loads and influences which are accepted at calculation of silos are listed. The basic formula of check of the general durability of a wall of a silo is resulted, the components of the formula are decrypted. The algorithm for calculating the spiral-folded silage is given.