在化工生产中，存在着高温高压、易燃易爆、有毒有害。腐蚀、触电和高处坠落等不安全因素。同这些不安全因素相关的要害作业如动火、动全、设备检查、抽培盲板。高处作业、进塔入罐、吊装、用电等都要实行作业许可证制度。作业票证是确保安全生产、防止事故发生的重要保证手段 In chemical production, there are high temperature and pressure, flammable, toxic and harmful. Corrosion, electric shock and fall from height and other unsafe factors. With these unsafe factors related to the key operations such as hot, moving all, equipment inspection, training blind. Height operations, into the tower into the tank, lifting, electricity, etc. must implement a permit system. Job ticket is to ensure safe production, to prevent an accident an important means of guarantee