by Jackie Johnson Jackie Johnson No Comments

The Illustrious History of PTFE

Spring Energized PTFE Seals

Today PTFE is one of the most widely used materials in the world. So, it may come as a surprise to learn that it was discovered entirely by accident!

How was PTFE discovered? In April of 1938, Dr. Roy Plunkett and his assistant Jack Rebok were working as chemists at DuPont’s Chemors Jackson Laboratory in New Jersey. On the night of the 6th, they stored the gas they were experimenting on (tetrafluoroethylene) in small cylinders where they were then frozen and compressed.

When the men returned the next day, they discovered that the gas they stored was gone. When they released the nozzle of the cylinders, no gas was released. Thinking this odd, they split the cylinders open to find the gas had turned into a solid, white, and waxy material.

This material would later become known as PTFE (polytetrafluoroethylene) or better known by its brand name Teflon.

The History of PTFE

Dr. Plunkett continued research on this strange new material and found that it was not only one of the slipperiest materials known, but that it also had several other incredible properties such as:

  • Non-Corrosive
  • Chemically Stable
  • Extremely High Melting Point

In 1941, Kinetic Chemicals Inc, a company founded by DuPont and General Motors, patented the new fluorinated plastic. In 1945 the name Teflon was trademarked. By 1948, Kinetic Chemicals was making over two million pounds of the Teflon brand PTFE.

PTFE-Coated Cookware

It wasn’t until 1954, when French-woman Collette Grégoire, wife of engineer Marc Grégoire, asked him to try the material he had been using on fishing tackle on her cooking pans. He subsequently created the first non-stick pans under the brand name Tefal (which is an amalgamation of “Tef” from “Teflon” and “al” from aluminum). The first PTFE-coated pan was introduced in the US in 1961 as “the Happy Pan”. Since then, non-stick cookware has been a staple in kitchens around the world.

Aside from cookware, PTFE has been used in a wide variety of applications, from food processing to the space industry. In fact, PTFE was used in the initial moon landing in 1969, as it was the only plastic that could withstand the extreme atmosphere of space.

Since then, PTFE has become a staple in our everyday lives and will continue to be so for many more years to come.

Need PTFE sealing solutions? Contact us today for more information!

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring Energized Seals in the Oil and Gas Industry

The oil and gas industry is home to some of the most intense operating conditions for seals: HPHT (High Pressure, High Temperature), corrosive chemicals, and very dangerous repercussions if seals fail. When all other sealing solutions fail, spring-energized seals are often the answer.

How are spring energized seals used in the oil and gas industry? Spring energized seals are used for a variety of applications including valves, well head connectors, couplings, loading swivels, and more.

Spring Energized Seals in Oil and Gas Applications

Seals are used throughout the oil and gas industry, including applications as diverse as …

  • Anti-Blow Out Seals
  • Couplings
  • Downhole Tools
  • Emergency Release Systems
  • Loading Swivels
  • Logging Tools
  • Quick Connect/Disconnect Couplings
  • Rotary Drill Bits
  • Surface and Subsea Well Heads
  • Swivel Stack Seals
  • Top Drive Units
  • Valves
  • Well Head Connectors

A seal failure in any of these areas could quickly lead to injured personnel, environmental damage, and ruined equipment. Seals for such applications must be rugged, reliable, and chemically resistant. They must be compatible with corrosive chemicals such as H2S, aromatic hydrocarbons, supercritical CO2, oil, and methanol,–and they need to be resistant to chemical permeation, as well. They generally need to be flameproof, tough, and wear-resistant as well.

Spring-Energized Seals

A spring-energized seal has a spring (the energizer) that applies additional force to the seal lip to maintain contact between the lip and the sealing surface. This energizing effect can account for issues related to dimensional changes, extreme pressure variations, wear on the edge of the seal lip, and other phenomena that can lead to a leaking seal. 

With the right choice of spring geometry, a constant force can be applied to the sealing lip to ensure its full engagement with the sealing surface, even through extreme pressure variation, temperature changes, wear on the shaft, and alignment issues. Spring energized seals can also be used with backup rings, or BURs, to prevent extrusion problems with the seal lip.

Lip Materials for Spring-Energized Seals

The seal lip material is also key, with the most commonly used polymers for oil and gas sealing challenges being PEEK and PTFE. They are both chemically inert, tough, wear-resistant, flame resistant, and offer outstanding performance even in the presence of extreme temperatures. Both of these materials work extremely well with spring energizer to result in excellent spring-energized seals for the oil and gas industry. They also have very low coefficients of friction and low CTEs (coefficient of thermal expansion).

PEEK performs well at pressures up to 20 kpsi, has a maximum temperature operating temperature of 500°F, and is also available will fillers to provide additional strength and hardness. Many grades PTFE has a maximum operating temperature close to 575°F and can handle high pressures. They are both dry running, as well, which makes them ideal for situations where traditional lubrication is not feasible.

Conclusion

If you are in the market for a reliable sealing solution for an oil and gas application, be sure to consider spring energized seals. They perform where many other types of seals fail, can be used with backup rings, are commonly used in petrochemical applications, and can be designed with a PEEK or PTFE seal lip for maximum performance.