SERVICE

LETTER

Wärtsilä low-speed engines RT-101

Services 2-stroke Issue 1, 26.11.2010

IFA end flange leakage For immediate attention

Concerned components
Flanges and lip seals located on the
Intermediate Fuel Accumulator of Wärtsilä
Information to all Owners and Operators of RT-flex96C-B and RT-flex84T-D engines.
Wärtsilä RT-flex96C-B and RT-flex84T-D engines
Current situation
Wärtsilä received reports about leakages
from the Intermediate Fuel Accumulator
(IFA). Investigations showed that the
leakages arise between the flanges and lip
seals of the IFA.

Solution
In order to avoid heavy leakages, Wärtsilä
recommends checking the drain pipe from
IFA on the fuel leakage device on regular
intervals of two weeks.
If leakage at the IFA flanges is detected,
the corresponding flange and lip seal must
be replaced.
If no spare flange is available, this Service
Letter provides an onsite emergency
machining procedure.

Note
Generally, no leakage at the IFA end
flanges is allowed.

Next step
Wärtsilä recommends distributing this
document immediately to all installations
where the above listed engines are
installed.

Wärtsilä Switzerland Ltd. Tel (24h): +41 52 262 80 10

PO Box 414 Fax: +41 52 262 07 31
CH-8401 Winterthur technicalsupport.chts@wartsila.com
 SERVICE LETTER RT-101
Issue 1, Page 2 / 7

Contents
Page

Introduction 2
Leakage location 3
Intermediate actions 3
Emergency machining onsite 5

Introduction
Recently Wärtsilä received an increased number of reports about leaking
Intermediate Fuel Accumulators (IFA). Investigations showed that the leakage is
between the lip seal (4) and flange (2) mounted on the end of IFA (3). The
reports showed also that the leakage on the IFA was mainly found at the end
where the pressure control valve (1) is mounted.

Intermediate fuel accumulator (IFA), drawn for RT-flex96C-B

1 3

2 4

1. Pressure control valve, 2. Flange between pressure control valve and IFA,
3. IFA, 4. Lip seal, 5. End flange
Fig. 1

At the beginning, the leakage amount is minor but detectable after opening the
shut-off valve. The leakage will increase over the period the engine is in
operation. Leakages from the IFA lead to a pressure drop in the fuel system
which might result in engine starting problems. In order to avoid any starting
difficulties of the engine, we recommend following the advice hereafter.
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Leakage location
A guideline and procedure how to localise leakages on the IFA are described in
the Wärtsilä Technical Bulletin RT-87 “Intermediate Fuel Accumulator”. Therefore
please refer to Chapter 6 of that particular Technical Bulletin. This Service Letter
RT-101 describes only the leakage at the end flanges of the IFA.

Intermediate actions
In order to avoid any leakages at the end flanges of the IFA which might lead to
other engine operational problems, Wärtsilä strongly recommends following the
steps below:
On regular intervals of two weeks open the corresponding leakage shut-off
valve of the IFA fuel leakage inspection device (1) and check if any fuel oil has
collected. If fuel oil is detected would confirm that there is a leak.
Regularly carrying out this check ensures early detection and gives the
possibility for repair before such leakage becomes serious enough to affect
engine operation and reliability.

Location of fuel leakage cocks

1. Fuel leakage inspection device

Fig. 2

Note:
The position of the fuel leakage inspection device and respective cock might look
different than the one shown in Figure 2 and thus depends on the respective
installation.

When leakage is detected at the corresponding flange, release the fuel pressure
and remove the end flange for inspection.
For pressure release please consult the respective engine manuals and the
Technical Bulletin RT-87 “Intermediate Fuel Accumulator”, Chapter 6, Paragraph
“Depressurisation of the system and IFA”.
If any damage and erosion marks (2) at the flanges (1) and lip seals (3) of the
IFA have been detected, the following action is required:
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Important:
Before opening any end flange, make sure the corresponding parts are available
on board the vessel as stock items.
At any removing of the flange, the lip seal has to be replaced with a new one.

Erosion marks on flange and lip seal

1 2 3

1. Flange, 2. Flange section with erosion marks, 3. Lip seal with erosion marks
Fig. 3

Replace the flange (2) part # DF 87502, lip seal (4) part # DF 87523 and all
twenty hexagon socket head cap screws (1) part # DF 87519, fixing the flange
to the IFA (3), see Figure 4.

Attention:
Tighten the hexagon socket head cap screws in steps and crosswise with the
correct torque according to the Maintenance Manual Group 0, Chapter 0352-1
“Tightening Values”.

Mounting of flange to IFA

2
3

3 1

1. 20x Hexagon socket head cap screws M16 – DF 87519, 2. Flange –

DF 87502, 3. IFA, 4. Lip seal- DF 87523
Fig. 4
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Emergency machining onsite

If the situation arises where the engine cannot be started again, no spare flange
to the IFA is available on board and the leakage cannot be stopped, Wärtsilä
provides hereafter an “Emergency procedure” for machining the flange onsite.
Before removing the flange from the IFA, make sure that in this case a new lip
seal is available on board.

Emergency procedure
The machining has to be made on a lathe. When mounting the flange to the
lathe, make sure that the parallelism of the plane surface B to the sealing surface
A is within the tolerance of +/-0.02 mm. The surface A must have a flatness
within a tolerance of 0.02 mm.

Machining of flange to IFA

1 2 1 (Dimensions in mm) B

1. Flange to IFA, 2. IFA, A. Sealing surface of flange, B. Plane surface of flange

Fig. 5

For a correct sealing function, the distance of the offset, plane surface B to the
sealing surface A has to be 25 mm with a tolerance of +/-0.02 mm. Therefore
machining both surfaces in the same clamping position must be ensured in order
to reach the specified tolerance.
The sealing surface A has to be machined concentrically. Make sure that the
sealing surface A is smooth and has a roughness of max. Ra0.8 (N6).
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References to machined surfaces and allowed roughness

As the on-board machine shop might not have all the special tools to determine
machining surfaces including their roughness, below are some hints how to
compare the machined surfaces with parts of same surface quality.

Example of a concentrically machined surface

1. Concentrically machined surface – sealing surface of flange before on-board

machining
Fig. 6

For a reference to the surface roughness of Ra0.8 (N6), please compare with the
plane sealing surface of the main collector (1) which is having the same
roughness tolerance.

Reference to the surface roughness

1. Main collector (IFA), 2. Plane sealing surface, roughness Ra0.8 (N6)

Fig. 7

Important:
The machined flange is weaker as the original one. The risk for faster leakage is
higher due to the changed geometric form.
Therefore the machined flange has to be replaced with an original part at the next
opportunity.
 SERVICE LETTER RT-101
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Planned further action

As soon as the investigation has been completed, Wärtsilä will issue a new
Service Bulletin describing the final solution.

For questions about the content of this Service Letter or if you need Wärtsilä
assistance, services, spare parts and/or tools, please contact your nearest
Wärtsilä representative or send your enquiry to:
technicalsupport.chts@wartsila.com
or phone 24hrs Support: +41 52 262 80 10.

© 2010 Wärtsilä Switzerland Ltd. – All rights reserved

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in this publication and assumes no responsibility for the correctness, errors or omissions for information
contained herein. Information in this publication is subject to change without notice.
Unless otherwise expressly set forth, no recommendation contained in this document is to be construed as
provided due to a defect in the engine, but merely as an improvement of the engine and/or the maintenance
procedures relating thereto. Any actions by the owner/operator as a result of the recommendations are not
covered under any warranty provided by Wärtsilä and such actions will thus be at the owners/operators own
cost and expense.
NO LIABILITY WHETHER DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL, IS
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CONFIDENTIAL AND INTENDED FOR INFORMATION PURPOSES ONLY.