Service Letter SL2020-699/JRR

Action code: WHEN CONVENIENT

Regular operation of
EGR systems
- EGRBP and EGRTC systems

SL2020-699/JRR
July 2020
Dear Sir or Madam
Concerns
Recently, we have received reports of malfunctioning EGR systems Owners and operators of MAN B&W
after longer periods of standstill or irregular usage. Based on our two-stroke marine diesel engines.
findings, we would like to emphasise the importance of maintaining Type: All engines with EGRBP and
the functionality of the EGR system to minimise the risk of failing EGRTC
systems due to sticking valves, stuck blowers or blocked filters, etc.
Summary
We recommend that EGRBP (exhaust gas recirculation bypass) and Guidelines for regularly operating
EGRTC (exhaust gas recirculation turbocharger cut out) systems are EGRBP and EGRTC systems to
function-tested according to the scheme in Table 1. minimise the risk of failing systems due
to sticking valves, stuck blowers or
If you have any questions or inquiries regarding this Service Letter, blocked filters, etc.
contact our Operation Department at
Operation2S@man-es.com.

For questions regarding spare parts contact PrimeServ at

Yours faithfully

Mikael C Jensen Stig B Jakobsen

Head office (& po. address) PrimeServ Production Forwarding & Receiving MAN Energy Solutions
MAN Energy Solutions Teglholmsgade 41 Teglholmsgade 35 Teglholmsgade 35 Branch of MAN Energy Solutions
Teglholmsgade 41 2450 Copenhagen SV 2450 Copenhagen SV 2450 Copenhagen SV SE, Germany
2450 Copenhagen SV Denmark Denmark Denmark CVR No.: 31611792
Denmark Phone: +45 33 85 11 00 Phone: +45 33 85 11 00 Phone: +45 33 85 11 00 Head office: Teglholmsgade 41
Phone: +45 33 85 11 00 Fax: +45 33 85 10 49 Fax: +45 33 85 10 17 Fax: +45 33 85 10 16 2450 Copenhagen SV, Denmark
Fax: +45 33 85 10 30 PrimeServ-cph@man-es.com manufacturing-dk@man-es.com shipping-cph@man-es.com German Reg.No.: HRB 22056
info-cph@man-es.com Amtsgericht Augsburg
www.man-es.com
Service Letter SL2020-699/JRR

Recommendations for maintaining EGR functionality It is possible to start the EGR system when the engine is
We recommend that EGR systems are started every running with 15-80% engine load.
second week (14 days) and that they are kept running for
two hours, see Table 1. This is done to make sure the If Tier III mode is requested on the ECS MOP and the
water treatment system (WTS) has circulated water engine load is below 15%, the EGR system will remain in
through the buffer tank and flushed away any build-up of standby mode until the engine load is above 15%.
particles/granulate in the EGR system.
If Tier III mode is requested above 80% engine load, the
EGR operation on compliant fuel ECS will automatically reduce the load to 80%, start up the
EGR systems are designed as either low-sulphur (<0.1% S) EGR system and load up to the previous speed setting
or high-sulphur (>0.5% S and <3.5% S) EGR systems, but without the load programme active.
recent studies show that the low-sulphur EGR system can
operate continuously on fuels with up to 0.5% S. The For the EGRTC system, the turbocharger has to be cut out
amount of sodium hydroxide (NaOH) required to neutralise manually to enable start of the EGR system. The request
the sulphur will be relative to the sulphur content of the fuel. for turbocharger cut-out (TC cut-out) is made on the ECS
MOP in the menu “Scavenge air” and cut out will be
All ECO EGR configurations are already 0.5% S ready. If available if the engine load is below 10%.
the vessel operates in ECA areas, keep in mind that the
maximum allowed sulphur content is 0.1%. Test of the EGR system with stopped engine
If operators are not able to test the complete EGR system
Depending on the EGR setup, the alarm “Fuel sulphur while the engine is running, it is recommended that the
content too high” may occur when trying to operate the following items are checked as during standstill.
EGR system on a fuel with 0.5% S. In that case, contact 1. Make a function test of EGR gas valves by changing
our Operation department for further assistance at opening and closing setpoints from the EGR MOP in the
Operation2S@man-es.com menu “EGR Gas”. Visually check the following valves,
locally:
Start of the EGR system with the engine running – Blower throttle valve(s) - BTV1 (BTV2)
For correct start-up of EGR systems, the following has to – Cylinder bypass valve - CBV
be fulfilled: – Shut off valve - SOV
1. The engine is running on the correct type of fuel.
If you have a low-sulphur EGR system, the If you have an EGRTC system, activate TC cut-out on
sulphur-content in the fuel oil can be up to 0.5%, the ECS MOP in the menu “Scavenge air”. The blower
otherwise you have to change fuel and adjust the bypass valve (BBV), the compressor cut-out valve (CCV)
sulphur content on the ECS MOP in the menu “Cylinder and the turbine cut-out valve (TCV) will close.
lubrication”. If you have a high-sulphur EGR system, you
will be able to start up without further adjustments. 2. Make a function test of the EGR blower by manually
starting it from the emission reduction control system
2. The water treatment system (WTS) is started according (ERCS) MOP in the menu “EGR Gas” and adjusting
to maker’s instructions and in automatic mode. blower rpm to minimum rpm.

3. The supply unit (SU pump and NaOH pump) is powered 3. Make a function test of the EGR process water system.
up and in automatic mode. The EGR water system can be run manually from the

Table 1: EGR system usage intervals

Engine type
EGRBP EGRTC
Engine running configuration - TC cut-in TC cut-out

Tier III running (Complete EGR running) Every 2 weeks N/A Every 2 weeks
Manual running of water system Every 2 weeks Change to TC cut-out mode Every 2 weeks
or stop engine
Valve exercise Every 2 weeks Every 2 weeks Every 2 weeks
(Manual movement of valves) (only possible during port stays) (only possible during port stays) (only possible during port stays)
EGR blower starting Every 2 weeks Every 2 weeks Every 2 weeks
(only possible during port stays) (only possible during port stays) (only possible during port stays)

Regular operation of EGR systems. Page 2 of 3 pages

ERCS MOP by requesting “Manually Run EGR Water” in Recommendations for taking EGR systems out of
the menu “Water Recirculation”. This will start the EGR operation for longer periods
water loop if the level in the WTS buffer tank is If the EGR system is not going to be operated for a longer
sufficient. If the water level is too low, add freshwater to period of time (1 year) it is recommended to disable and
the buffer tank according to maker’s manual. We blank it off:
recommend to keep the water loop running for half an
hour to flush the EGR tank and pipes. 1. EGR gas pipes
The SOV string must be blanked-off with a plate either
If you are not able to start the water system manually, before or after the SOV, depending on the location of
then you have to check each valve separately as the SOV. The BTV must not be blanked-off since it is
mentioned in item 4. exercised regularly by the EGR control system, and the
BTV venting line ensures that the EGR unit pressure
4. Make a function test of EGR water valves by changing follows the scavenge air pressure.
opening and closing setpoints from the EGR MOP in the
menu “Water Recirculation”. Visually check the 2. Sensor unit cabinet (SUC)
following valves, locally: Close the ball valves on the gas probes mounted on top
– Mixing chamber drain valve – MCDV of the scavenge air receiver. Stopping the gas flow will
– Spray water sealing valve – SWSV activate a low-pressure alarm on the SUC cabinet,
– Process water sealing valve – PWSV which will activate the SUC Common Alarm in the
– Receiving tank level valve – RTLV ERCS. This alarm should be inhibited while the EGR is
– Freshwater supply valve - FWSV out of service.

If you have an EGRTC system, check valves: 3. EGR process water pipe
– EGR unit water trap valve – EUWV No further action is needed for the EGR process water,
– EGR unit drain valve – EUDV but if it is decided to drain the Receiving Tank Unit
(RTU), the pH sensors must be removed and stored
according to the manual.

4. Supply unit
Inlet and outlet valves for the treated water supply
pump (TWSP) and the NaOH connection must be
closed.

Regular operation of EGR systems. Page 3 of 3 pages