When Choosing a Valve, the Body Material Is Important — but the Seal Is the Real Limiting Factor. Many people believe that as long as a valve is made of high-temperature-resistant stainless steel, it can easily handle harsh conditions such as hot boilers and chemical reactors. But in real operation, what often fails first is not the valve body — it’s the seal. Seals may soften, crack, or lose elasticity under high temperature, leading to media leakage, pressure loss, and in serious cases, safety accidents. 

In fact, the maximum operating temperature of a valve is not determined by the body material, but by the sealing material.The most common valve sealing materials on the market today include: NBR (Nitrile Rubber), PTFE (Teflon / Polytetrafluoroethylene), EPDM (Ethylene Propylene Rubber), and VITON (FKM / Fluororubber). This article explains the performance differences among these four materials and helps you choose the right seal for high-temperature applications.

The “Weak Point” of High-Temperature Valves: Seals

Seals may look small and insignificant, but they are the core of leak prevention — much like the rubber ring in a household water pipe. In industrial valves, seals serve two main purposes:

1. The First Line of Defense Against Leakage

When the valve closes, the seal presses tightly against the valve core and seat to block the flow of media. Whether it’s 100+°C steam or other hot fluids or gases, the seal is what prevents leakage. If the sealing material cannot withstand the temperature, leakage becomes inevitable — wasting materials, damaging equipment, polluting the environment, and creating safety risks.

2. Resistance to Temperature, Pressure, and Friction

Seals endure constant friction during valve opening and closing, pressure fluctuations, and — most critically — continuous heat exposure. If the temperature exceeds the seal's limit, the material may soften, deform, age rapidly, or even carbonize, causing complete sealing failure.

Comparison of the Four Common Sealing Materials

The four most widely used sealing materials in industrial valves differ greatly in temperature resistance and application scope. Choosing incorrectly can lead not only to shortened service life but also to safety hazards.

How to Choose Seals for High-Temperature Applications

If your valve operates above 150°C, prioritize PTFE or VITON, depending on the medium and pressure.

Option 1: 150–260°C with Corrosive Media → Choose PTFE

For strong acids, alkalis, or aggressive chemicals, PTFE offers the best performance. Because PTFE has limited elasticity, choose composite designs such as: PTFE + rubber backing /Spring-energized PTFE seals. This way, the seal can still fit tightly against the sealing surface without leakage even at relatively low temperatures.

Option 2: 150–200°C with High Pressure (No Strong Corrosion) → Choose VITON

For steam, fuel, and lubricating oil under high pressure (>1.6 MPa), VITON is ideal. It maintains tight sealing even after long-term use. In automotive engines and industrial boilers, VITON seals typically last 5–8 times longer than NBR, significantly reducing maintenance costs.

The Key to High-Temperature Valves Is the Seal , Not Just the Body. For normal conditions: NBR or EPDM provides the best value; For high temperatures: choose PTFE or VITON based on medium and pressure.

Do not focus only on the valve body, selecting the correct seal material is far more important. Choosing the right seal ensures long-term system stability, minimizes downtime, and prevents costly leaks and failures.

If you also need to use any type of pneumatic valves in your system, you can contact us directly.

(FK9025)