TURBOMACHINERY BEARINGS AND SEALS

Mark Hinckley, Director of Strategic Projects at SKF USA, discusses trends in the marketplace as well as the latest bearings, seals and monitoring services available.

Tell our readers briefly about SKF.

SKF is a global supplier of bearings, seals, mechatronics, lubrication systems and services which include technical support, maintenance and reliability services, engineering consulting and training.

SKF continuously develops new technologies, enabling customers to use them to create products that deliver rotating equipment performance that offers a competitive advantage. Our company is represented in more than 130 countries and has around 17,000 distributor locations.

What products do you produce for the turbomachinery marketplace?

The company is best known for high-performance, rolling element bearings, which include bearings with special steels and heat treatments. SKF also manufactures bearings and seals with materials and coatings for pumps, compressors and other turbomachinery in aggressive environments.

We also provide seals, lubrication systems and monitoring equipment. Additionally, new centrifugal compressor designs take advantage of efficiency gains from higher speed, non-contacting rotation. Magnetic bearings paired with high-speed motors, therefore, have become increasingly prevalent and SKF is a leading supplier of magnetic bearing technology.

What recent product would you like to feature?

SKF high-nitrogen stainless steel hybrid bearings have rolling elements made from bearing-grade silicon nitride and a glass fiber reinforced polyetheretherketone (PEEK) cage. It greatly improves performance, enabling bearings to run longer than conventional hybrid bearings, particularly in harsh conditions like those found when handling sour gas (H2S).

What trends have you observed?

We have noticed several evolving trends. Speeds are increasing to take advantage of improvements in centrifugal compression efficiency. The operation of compressors in aggressive environments that would kill traditional bearings is also becoming commonplace due to the use of magnetic bearings. As there is no contact, the bearings can operate even when exposed to harsh conditions.

In addition, we’re seeing an increase in high nitrogen stainless steel hybrid bearings that extend the life of a machine compared to traditional rolling element (RE) bearings. Since these bearings are manufactured to the same dimensions as traditional RE bearings, it can be a relatively straight forward upgrade for applications suffering from failures due to an aggressive operating environment.

What trends have you observed related to seals?

There is a never-ending push to optimize the life and performance of seals. Smaller packaging, longer life and lower friction are all important elements. Magnetic bearings that don’t require seals to keep lubrication in can be designed to operate where they are exposed to the process gas without degrading the bearing or its performance. Tight air gaps and seals can still be used to optimize fluid dynamic efficiency by isolating the process and the more effective the sealing of the compressed fluid.

Further SKF’s Kaydon rings and seals serve demanding applications in the oil and gas, aircraft, aerospace and other industries. This includes dry gas shaft seals, mechanical seals, aircraft gas turbine engine carbon seals, critical sealing rings, diesel engine piston rings and natural gas engine power piston rings.

What trends have you observed on condition monitoring?

Condition monitoring solutions for turbomachinery are becoming more compact and powerful. For example, the SKF IMX8 Multilog Condition Monitoring System provides early fault detection, prevention, automatic advice and advanced maintenance for improved reliability and performance. It offers eight-channel health monitoring and is internet-enabled for remote access. It provides up to 16 channels per device for early fault detection and prevention.

In addition, magnetic bearings can be a game changer in this arena. As part of the normal operation of a magnetic bearing, a tremendous amount of data is processed regarding machine operation. This data can provide insight into how the process is performing, not only the condition of the rotating equipment.

How are AMBs doing in the marketplace?

Active Magnetic Bearings (AMBs) are growing in acceptance and use. In areas like HVAC, end users are moving from having a preference to an insistence upon magnetic bearings. Their price point, paired with higher levels of functionality and feedback, are appealing to a broader audience. In applications such as water-cooled chillers, magnetic bearings are now part of the standard offering.

Magnetic bearings are deployed with success in a wide range of applications. One example is the Åsgard Subsea Gas Compression facility. Our lubrication-free magnetic bearings were chosen for their strength, reliability and compactness with zero-maintenance requirements.

These bearings have been operating problem free with ~100% availability since they were installed in September of 2015. The two 11 MW compressors have more than 60,000 accumulated hours since installation. Magnetic bearing technology has also been installed and tested in over 115 naval applications, including nuclear submarines.