Material guide
FEP, fluorinated ethylene propylene
FEP, fluorinated ethylene propylene. A meltable fluoropolymer with almost the same chemical resistance as PTFE, and on top of that it is see-through and easy to form. It belongs in hoses, liners and coatings where you want to see the medium and still have full chemical protection.
What it is
FEP stands for fluorinated ethylene propylene and belongs to the fluoropolymers. Like PFA it is a meltable relative of PTFE, which means it can be processed in the melt and gives smooth, tight surfaces. FEP has broad chemical resistance, very low friction and is often see-through, a property that sets it apart from most other plastics in this class. The chemical resistance is close to PTFE and PFA, but FEP takes a slightly lower continuous temperature and usually costs less than PFA. The material is a premium choice, picked for the combination of chemical resistance, purity and transparency. The group is described in more detail further down.
Properties
Broad chemical resistance, close to PTFE, stands up to most aggressive media
Often see-through, you see the medium through hose and liner
Can be processed in the melt, gives smooth and tight surfaces
Very low friction and good release properties
Excellent electrical insulator
Physiologically inert, suitable for pharmaceutical and food contact
Common applications
FEP sits where chemical resistance meets the need for transparency or melt processed parts. Typical applications are hoses and tubes where you want to see the flow, liners and coatings in vessels and tubes, and insulation in cable and electronics. The material is used in laboratory and analysis equipment and in pharmaceutical and food applications where purity is a requirement. When a customer needs PTFE-like chemical resistance but in a formable and preferably see-through form, FEP is often the answer.
Limitations
FEP takes a lower continuous temperature than PTFE and PFA, so for the hottest environments you are better off with one of those. Like the other fluoropolymers, FEP is soft and has limited mechanical stiffness, which makes it unsuitable for load carrying structural parts. It is an expensive specialty material, so it gets picked for its properties, not to save money. If you only need good chemical resistance without transparency, PTFE or PVDF often do the same job. On top of that, we carry FEP in a limited number of formats, see below.
Our FEP grades go to 205 °C in continuous service. That is lower than both PTFE and PFA, so if you need more heat those two are the ones to look at.
Grades and variants
FEP is a pure fluoropolymer and one of the most chemically resistant plastics in the range. The grades differ mainly in the form they are supplied in.
Base grades
- FEP standard form, the most common supply form, often see-through, with broad chemical resistance and high purity.
Additives and reinforcements
- Welding rod and roll, for jointing and lining in chemically exposed and clean installations.
FEP and PFA are close relatives with similar properties. The main difference is that PFA takes a higher temperature and costs more, while FEP is often cheaper and see-through. Not sure which one fits? Get in touch and we will go through the application with you.
Machining
FEP is soft and yielding, and you notice it right away when machining. It can be turned and milled, but the part wants to spring away from the tool, so keep the feed down and the cutting edges sharp. Adhesives do not stick without pretreatment.
Formats we can supply
We carry FEP as sheet, and also as roll and welding rod. You see formats and dimensions in the range. Want a piece cut to size? Enter the dimensions in VisualCutter and you see the price right away.