June 2019

PTFE Seals – When Elastomers Aren’t Up to the Task

Elastomers are often the first choice for sealing and gasketing, but they’re not always the best. Silicone, neoprene, EPDM and Buna-N all have limitations that disqualify them from some applications. When that’s the case it may be time to consider PTFE seals.

Limitations of Elastomers

Elastomers are challenged by temperature extremes, aggressive chemicals and UV light. Some swell when in contact with oils, others outgas or give up molecules to the fluid being sealed against.

Food processing is a difficult environment. While it’s important to avoid product taint the materials must also endure aggressive cleaning regimens. Medical and pharmaceutical equipment presents similar challenges.

Many elastomeric materials harden in UV light, making them unsuitable for outdoor environments. Others will outgas, making them a bad choice for vacuum applications.

How PTFE Seals Score

PTFE is composed of carbon atoms bonded to fluorine. That makes it almost totally inert and a good choice for food, pharma and medical applications.

Less flexible than an elastomer, PTFE can nevertheless seal down to around -460°F. It’s also functional at temperatures as high as 570°F.

PTFE is unaffected by UV light, making it useful for outdoor applications or those involving UV sterilization. It has excellent electrical insulating properties and won’t swell when exposed to steam or oils. Another benefit from using PTFE seals in dynamic applications is a very low coefficient of friction.

PTFE Seals Limitations

Under load, especially at elevated temperatures, PTFE will creep. Joints should be designed to minimize the clamping forces applied directly to the material.

A second limitation is low strength. Some elastomers offer higher tensile strength combined with less elongation at breakage.

To address these issues PTFE formulators incorporate a range of fillers. Ranging from glass and carbon fiber to bronze and molybdenum disulfide, these can increase strength and hardness and reduce friction.

Seek specialist advice

When your sealing application challenges elastomeric materials it may be time to consider PTFE. However, with a large number of PTFE formulations available it’s difficult to know which is ideal. In such cases consult a materials specialist like those at Hennig Gasket.

Garlock Gasket Material – A trusted Name

Trust takes time to earn but can be lost in seconds. That’s why people stick with brands that have served them well. Why risk something new when you already know what works? For this reason, many gasket buyers specify Garlock gasket material. Either they’ve had good experience with it or they know someone who has.

About Garlock

Garlock has been around for over a century, so they’re doing something right. While their business is sealing, Garlock focuses on the benefits gaskets deliver: keeping people safe and helping businesses be more profitable.

One hundred years ago we used natural materials like rubber and leather but industrial processes have changed since then. Today, increased temperatures and pressures demand gasket material that’s stronger and more resilient.

Garlock invests heavily in R&D to develop innovative materials that meet these challenges. Their research and testing facilities are state-of-the-art and they have a strong environmental commitment. Together, this ensures Garlock gasket material stays at the forefront of sealing technology.

An overview of Garlock gasket material

Whether you’re dealing with extreme temperatures, high pressures, vacuum or aggressive chemicals, there’s a Garlock material to suit. Scan their product catalog, (or speak with a Hennig specialist,) and you’ll discover PTFE in many grades, graphite, compressed fiber, and natural and synthetic rubber gaskets and gasket material.

Brand names you may be familiar with include GYLON® restructured PTFE, GRAPH-LOCK® flexible graphite sheet, BLUE-GARD® compressed rubber and THERMa-PUR Extreme Temperature material.

Known for excellent chemical resistance, GYLON® is used in many industries including pharmaceuticals and food processing. GRAPH-LOCK® is a high-temperature material with good creep-resistance. BLUE-GARD® also offers a wide temperature range and is available with a range of rubbers. THERMa-PUR, however, beats them all as it will operate at temperatures as high as 1,832°F (1,000°C).

A reputation you can trust

When a business endures you know it’s doing something right. Garlock isn’t the only company to make gasket material, but they’ve been at it a long time and make a quality product. If you’d like to use Garlock gasket material in your next project, speak to us.