Bearings answer petrochemical demands

Bearings are specifically designed to provide solutions to the economic and environmental issues facing the chemical and petrochemical processing industry.

Few working environments can compete with the potent mix of production demands and pressures routinely encountered in chemical and petrochemical processing.

Numerous rotating machines are required to successfully complete these processes and deliver products on time.

The use of bearings in such applications provides many technical challenges.

NSK has taken up these challenges: it has deployed its global knowledge of the petrochemical market, and its technical innovation, to produce a range of bearings specifically designed to provide solutions to the economic and environmental issues facing the industry.

As the primary equipment type used in petrochemical applications, centrifugal pumps continually test the endurance and integrity of rolling bearing designs.

The problems of handling difficult-to-pump corrosive liquids, the continuous operating regimes, and the critical nature of the applications themselves, mean that the pumps and their associated bearings are always under the maximum pressure to perform reliably and consistently over long periods.

NSK has responded to this challenge with solutions based on its EW/ET/EM series of cylindrical roller bearings, and paired BMPC series of angular contact bearings with 40 degree contact angles.

All of these bearings are designed to help extend the periods between pump failures.

BMPC series bearings exceed the API (American Petroleum Institute) 610 specification with the strongest machined brass cage in the industry, providing superior reliability in the harshest of applications.

They also achieve longer service life, through smoother running, reduced levels of friction and lower temperature rise; the latter as a result of the better heat dissipation of the brass cage material.

The BMPC Series design is an amalgam of high strength materials technology, ABEC3 (P6) manufacturing tolerances and pump specific axial internal clearances.

It delivers higher running accuracy, plus optimum levels of bearing stiffness, shaft positioning accuracy, load sharing and cooler running.

In addition, the combination of super finished raceways, lowest inner-ring run-out and tight tolerance ball grade, all contribute to reduced levels of ball skidding and, run-out reading to, smoother operation.

The BMPC bearings are manufactured with 40 degree contact angles to support both the axial and radial loading of pumps.

They also have universally ground faces, allowing mounting versatility on a wide range of shaft sizes from 20 to 150mm OD.

NSK's E series of cylindrical roller bearings (CRB) are used in conjunction with the BMPC angular contact bearings.

The EW/EM series CRB are capable of carrying particularly large radial loads, and are also suitable for high-speed applications.

The EW series features a pressed steel cage, and the EM series a one-piece machined brass cage.

Both of these cage designs offer higher-load ratings compared with standard size bearings (30% for EM; 20% for EW), giving a longer operating life: (approximately twice that of conventional CRB.) Another feature of the EW and EM cage designs is that their cage pockets are extremely precise.

The major benefit of this is enhanced accuracy in roller position, providing greater control over the rollers and helping to minimise excess vibration.

With the EW series, the reduction is between 30 to 50%; while that for the EM series is greater still, at 50 to 60%.

In addition to centrifugal pumps, the EM and EW series CRB are used on equipment such as displacement blowers and also on the electric motors that are used to drive all types of prime movers.

In displacement blowers the EM and EW series bearings carry radial loads, while the axial loads generated by synchronisation gears are carried either by NSK's double-row ball bearings or by pairs of tapered roller bearings.

As regards electric motors, the EW Series bearings are especially suitable for high temperature conditions experienced in smaller size electric motors where conventional designs of CRB cannot meet application needs.

The EM Series bearings are much more suitable for medium and large motors where low running noise is required.

They are also ideally suited for use in speed reducers and vibration equipment where harsh operating conditions are the norm.

The solutions provided by NSK's BMPC, EM, EW and angular contact bearings, while comprehensive, are not the total extent of NSK's offering to the chemical and petrochemical markets.

Supporting the latter products is the Spacea series, a range of bearings that provides high performance and reliability under all types of demanding operating conditions: super-clean, vacuum, non magnetic, corrosive, high/low temperature and high speed.

Spacea bearings meet the widest range of technical requirements with a programme of high performance materials, surface finishes and specially developed lubricants, including solid types.

Depending on the application, Spacea bearings can be manufactured from Martensitic and Austenitic stainless steels for corrosive environments, ceramics, or a combination of both.

Hybrid Spacea types can have any combination of ceramic inner/outer rings or balls, however, the range also includes all ceramic bearings for use in highly corrosive and high temperature environments.

NSK has detailed its innovative bearing products for the petrochemical industry in a new publication.

The free booklet provides a wealth of information regarding the choice of bearings for use in petrochemical applications.

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