Chemical engineering is the branch of engineering that deals with manufacturing products through chemical processes and the technologies of chemical production. Chemical engineering is based on a combination of physical sciences, life sciences, mathematics and economics. Chemical engineering deals with a number of chemical processes from the design, manufacture and operation of plants and machineries to performing tests and ensuring that safety issues related to the environment, the process and the product are considered at all stages. Some of the sub-disciplines of chemical engineering are: ceramic engineering, crystal engineering, drilling engineering, petroleum engineering.