You may think that because you work for a manufacturing company that you don't need a PE license. That is true in some states, but by no means all states.
The National Society of Engineers keeps track of the exemptions to the requirement of a PE license for persons performing engineering tasks. A summary they produced in August of 2016 showed only two states with no exemptions. However, a closer look provides a much different picture.
Many of the exemptions are for federal, state and municipal employees. Other exemptions are for special corporations such as telecommunications companies and public utility companies. Some states exempt employees involved in manufacturing operations but not in the development and design of the processes and facilities.
After a closer examination, about half of the states have no exemption for employees of manufacturing companies that might involve the employment of chemical engineers.
Your status will most likely change
Even if your state does exempt employees working for a manufacturing company, you still should consider obtaining your PE license to increase your promotion potential and job mobility. With the current practice of outsourcing many job functions, including engineering, your next job may likely be in an engineering service firm. There you will be required to either have a PE license, or you will have to be directly supervised by a PE engineer with a license in your discipline. As you can see, that "directly supervised" requirement greatly limits your entry level and advancement opportunities in the service company.