Service Letter SL2019-687/NHN Liner jacket cooling water for operation on low-sulphur fuels

In Service Letter SL2019-671 it is stated for the JBB and the load dependent cylinder liner (LDCL) cooling water system that closing down the LDCL system and deactivating any JBB system is recommended when using up to 0.50% S VLSFO.

The guideline in this Service Letter explains the procedure for deactivating the jacket cooling water bypass if installed in the main engine cooling circuit.

Concerns
Owners and operators of MAN B&W two-stroke marine diesel engines.
Type: All MAN B&W engines equipped with jacket cooling water bypass basic.
Summary
When using low-sulphur fuels, the jacket cooling water bypass can be deactivated on engines equipped with the:
–– Simple JBB
–– Common JBB
and the cover cooling water outlet temperature can be adjusted to 85℃.
Other relevant Service Letters are: SL2019-671