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.