7/28/2019 sb_ALL_a_029_01

1/3

Industrial Turbomachinery Ltd

Siemens Industrial Turbomachinery Ltd 2006

CONFIDENTIALThis 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 its 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 ourknowledge 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-ALL-A-029-01 Page1 of 3All 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

SB-ALL-A-029-01

SUBJECT: IMPELLER LIVES

A. TURBOCHARGERS AFFECTED

All NAPIER turbochargers.

B. REASONS FOR BULLETIN

As the rated pressure ratios of turbochargers increase, the creep life of the aluminiumimpeller material becomes more critical as a limiting factor in service. Other than forspecial applications where specific agreement has been reached, Napier design for aminimum impeller creep and fatigue life, in combination, as follows :-

NA297 and NA357Hours 50,000 at design pressure ratio at up to 25 deg C ambientCycles 50,000 no load to full load cycles

NA397Hours 50,000 at design pressure ratio at up to 35 deg C ambient

Cycles 50,000 no load to full load cycles

RECOMMENDED

7/28/2019 sb_ALL_a_029_01

2/3

SB-ALL-A-029-01 Page 2 of 3

NA298 and NA358 (under design and validation in 2003)Hours 50,000 at design pressure ratio and up to 45 deg C ambientCycles 50,000 no load to full load cycles

Other Napier Frame sizesHours 50,000 at design pressure ratio and up to 25 deg C ambientCycles 50,000 no load to full load cycles

This bulletin is issued to make customers, operators and service centres aware oflimitations in impeller life and provides advice on actions to be taken.

C. CHANGES / MODIFICATIONS

No material changes to turbocharger part designs are involved but all parties must be

aware of impeller service life limits and the need for timely impeller replacement.Customers and operators should note that although creep is a significant issue inimpeller service life, fatigue is also of major relevance. Data on operational cycles can bedifficult to collect accurately but, unlike a creep failure, exceeding the fatigue life of animpeller could result in a sudden and major impeller failure. Operators should be awareof this, keep all data available on load cycles and change impellers systematically ifoperating regimes and records indicate that fatigue lives are being exceeded.

D. DESCRIPTION

Based on the stated life of the impellers, Napier is introducing a simple system of datemarking on all new impellers and all impellers returned forming part of overhaul orremanufacture orders. Marking will be applied at the balance operation to ensure allimpellers leaving the Napier factory will be covered. For new impellers, the date will bethat of the balancing. For impellers which have been returned from service, the date willbe that of original impeller manufacture or turbocharger build, taken from Napier records.The marking will be etched on the leading edge pocket of the impeller hub in abbreviatedmonth-year format in accordance with Napier drawings and marking standards (e.g.JAN-99 will denote a date of January 1999).

E. IMPLEMENTATION

For purposes of turbocharger overhaul or remanufacture, Napier will assume, in absenceof contrary information from the operator, that impellers less than 8 years old will havecompleted less than 50,000 hours of full load operation and less than 50,000 load cycles.They will therefore be re-used under the normal commercial and guarantee conditions.Where impellers are found to be in excess of 8 years old, customers will be advised ofNapiers recommendation for change. The ultimate responsibility for any decision to re-use impellers in excess of 8 years old will be with the customer and/or equipmentoperator.

7/28/2019 sb_ALL_a_029_01

3/3