It is used for surface cleaning and stress removal of large h beam and box-shaped steel structures.The steel structure is subjected to multi-angle and intensive projectile attack and friction in the main chamber, then the oxidized skin, rust layer and its dirt quickly fall off, and the surface shows the metallic luster.The equipment includes main room, auxiliary chamber (two ends), projectile head, pellet circulation system, air cleaning and purification system, conveying roller system and control system.