SC123

SCSC
123
123

(1998)(cont)(Rev.1
Apr 1998)(Rev.2June 2002)(Rev.3
Dec 2005)(Rev.4
Nov 2018
Withdrawnand Rev.3
reinstatedNov 2019)(Corr.1
Feb 2022)(Rev.5July 2023)

Machinery Installations - Service Tank
Arrangements
Reg. II-1/26.11
SOLAS Regulation II-1/26.11 states:
Two fuel oil service tanks for each type of fuel used on board necessary for propulsion andvital systems or equivalent arrangements shall be provided on each new ship, with acapacity of at least 8 h at maximum continuous rating of the propulsion plant and normaloperating load at sea of the generator plant.
Interpretation
Arrangements complying with this regulation and acceptable “equivalent arrangements”, forthe most commonly utilised fuel systems, are shown below.
A service tank is a fuel oil tank which contains only fuel of a quality ready for use i.e. fuel of agrade and quality that meet the specification required by the equipment manufacturer. A
service tank is to be declared as such and not to be used for any other purpose.
Use of a setting tank with or without purifiers, or purifiers alone, and one service tank is not
acceptable as an “equivalent arrangement” to two service tanks.

Notes:
1. This Unified Interpretation is to be applied by IACS Members and Associates to all ships
subject to the relevant SOLAS Regulation.
2. Changes introduced in Rev.2 are to be uniformly implemented by IACS Members andAssociates from 1 January 2003.
3. Changes introduced in Rev.3 are to be uniformly implemented by IACS Members andAssociate from 1 July 2006.
4. Rev.4 of this UI is withdrawn prior to coming into force on 1 January 2020 and Rev.3 of this
UI is reinstated on Nov 2019.
5. Rev.5 of this UI is to be uniformly implemented by IACS Members on ships contracted forconstruction on or after 1 July 2024.
6. The “contracted for construction” date means the date on which the contract to build thevessel is signed between the prospective owner and shipbuilder. For further details
regarding the date of “contract for construction”, refer to IACS Procedural Requirement(PR) No. 29.

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SC123

SC123(cont)

1.

Example 1

1.1 Requirement according to SOLAS - Main and Auxiliary Engines and Boiler(s) operatingwith Heavy Fuel Oil (HFO) (one fuel ship)
HFO Serv. TK
Capacity for at least 8 h
Main Eng. +Aux. Boiler +Aux. Eng.

1.2

HFO Serv. TK
Capacity for at least 8 h
Main Eng. +Aux. Boiler +Aux. Eng.

MDO TKFor initial cold startingor repair work ofEngines/ Boiler

Equivalent arrangement (1)HFO Serv. TK
Capacity for at least 8 h
Main Eng. +Aux. Boiler +Aux. Eng.

MDO Serv. TK
Capacity for at least 8 h
Main Eng. +Aux. Boiler +Aux. Eng.

This arrangement only applies where main and auxiliary engines can operate with heavy fueloil under all load conditions and, in the case of main engines, during manoeuvring.
For pilot burners of Auxiliary Boilers if provided, an additional MDO tank for 8 hours may benecessary.

Any fuel oil which requires post service tank heating to achieve the required injection viscosity is notregarded in this context as MDO.
(1)

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SC123

SC
123(cont)

2.

Example 2

2.1 Requirement according to SOLAS - Main Engine(s) and Auxiliary Boiler(s) operatingwith HFO and Auxiliary Engine operating with Marine Diesel Oil (MDO)HFO Serv. TK
Capacity for atleast 8 h
Main Eng.+
Aux. Boiler

2.2

HFO Serv. TK
Capacity for atleast 8 h
Main Eng.+
Aux. Boiler

MDO Serv. TK
Capacity for atleast 8 h
Aux. Eng.

MDO Serv. TK
Capacity for atleast 8 h
Aux. Eng.

Equivalent arrangement (2)HFO Serv. TK
Capacity for atleast 8 h
Main Eng.+
Aux. Boiler

MDO Serv. TK
Capacity for at least
the highest of:
4 h Main Eng. +Aux. Eng.
+Aux. Boileror
8 h Aux. Eng. + Aux. Boiler

MDO Serv. TK
Capacity for at least
the highest of:
4 h Main Eng. +Aux. Eng.
+ Aux. Boileror
8 h Aux. Eng. + Aux. Boiler

3.
The arrangements in 1.2 and 2.2 apply, provided the propulsion and vital systems
which use two types of fuel support rapid fuel changeover and are capable of operating in all
normal operating conditions at sea with both types of fuel (MDO and HFO).

End ofDocument(2)

See footnote 1.

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