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NAPIER Turbochargers

© Siemens Industrial Turbomachinery Ltd 2006

CONFIDENTIAL This bulletin is the exclusive property of Siemens Industrial Turbomachinery Ltd and is disclosed in confidence to Siemens Industrial Turbomachinery Ltd customers solely for their use inconnection with the operation and maintenance of their Siemens Industrial Turbomachinery Ltd turbines. Its contents shall not be used for other purposes or copied or disclosed without writtenauthorisation of Siemens Industrial Turbomachinery Ltd. The information set out in this bulletin is offered by Siemens Industrial Turbomachinery Ltd as part of i ts ongoing product supportservices for you as one of its customers. However, the final decision for operating your plant in a safe and responsible manner rests entirely with you. This involves many factors outside our knowledge and control, and therefore Siemens Industrial Turbomachinery Ltd is unable to accept (and hereby disclaims) any liability (whether based on breach of contract, warranty or statutoryduty, negligence or otherwise) for damage or loss of any kind which may be incurred as a result of applying this information.

SB-295-A-032-01 Page1 of 3 All correspondence to:SiemensTurbochargers Division Siemens Industrial Turbomachinery LtdP.O. Box 1 Registered Office:Waterside South Ruston HouseLincoln LN5 7FD England Waterside SouthTel: +44 (0) 1522 584000 Lincoln LN5 7FD EnglandFax: +44 (0) 1522 584910 Registered in England No. 4729734

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SUBJECT: NA295 COMPRESSOR END SEALING

A. TURBOCHARGERS AFFECTED

All NA295 Turbochargers that experience extended periods of priming, or exhibit other operational oil leakage problems at the compressor end.

B. REASONS FOR BULLETIN

Instances of compressor end oil leakage have been experienced in some turbocharger installations. This is particularly so where engines are used for standby power generationcapacity, or are otherwise held in a priming condition for extended periods.

C. LEAKAGE RISKS

Compressor end oil leakage will be dependent on a number of factors including thepriming pressure applied, and the temperature and viscosity of the priming oil. Leakageoccurring during extended priming can cause an oil accumulation in the compressor volute, which can subsequently carry over into the engine airbox and intercooler withresultant fouling.

It is advised that checks for oil leakage are undertaken at the next routine turbocharger service interval unless oil leakage has already been noted, (e.g. through intercooler drains). It is stressed however, that not all NA295 turbochargers suffer compressor end

oil leakage.

ADVISORY

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D. PRODUCT VALIDATION

Napier Turbochargers have developed an improved sealing system for the NA295, whichincludes an additional oil thrower ring. This system has been tested in house by Napier and validated in service, on applications previously suffering leakage. Results have been

positive with no oil leakage detected.

E. COMMERCIAL IMPLEMENTATION

The current Re-manufacturing price list will apply to service exchange units requiring thisupgrade.

F. IMPLEMENTATION

The upgrade will depend on the availability of machining (fine grinding), balancingfacilities and/or spare cartridges. If the cartridge, or a spare cartridge can be shippedback to a Napier service centre, a full upgrade may be carried out. The option to upgradethe unit at site is possible, but machining (fine grinding) and balancing facilities must beavailable. The upgrade will include:

• Modification of the existing seal ring carrier (or installation of a new carrier).

• Modification of impeller

• Modification of rotor shaft

• Installation of a new seal ring bush

• Addition of a thrower ring in the rotor assembly

• Re-assembly and check balance/rebalance of the rotor shaft

NOTE: For some sites, Napier may be in the position to offer a cartridge exchangeservice but this will be by specific commercial arrangement. Cartridgeexchange is considered the most effective approach to implementation.

G. PARTS LIST

In the case of any queries, or to confirm the modification status of units in specificapplications, reference should be made to Napier Turbochargers for advice. All details of part number alterations and specification changes can be made available on request.

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Author R. S. AmosTechnical Manager

Authorised

TechnicalManager

R.S.Amos Head of Customer Services

P. Munnelly

GeneralManager

A. R. Thacker

Distribution:

Napier TurbochargersCaterpilar Motoren

Empowered Service Centres

Date of Issue: 21st July 2003

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