Section 18 Control and monitoring
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 5 Main and Auxiliary Machinery - Chapter 10 Steam Raising Plant and Associated Pressure Vessels - Section 18 Control and monitoring

Section 18 Control and monitoring

Parent topic: Chapter 10 Steam Raising Plant and Associated Pressure Vessels

18.1 General

18.1.1 Control engineering systems are to be in accordance with the requirements of Pt 6, Ch 1 Control Engineering Systems.

18.2 Unattended machinery

18.2.1 Where boilers are fitted with automatic or remote controls so that under normal operating conditions they do not require any manual intervention by the operators, they are to be provided with the alarms and safety arrangements required by Pt 5, Ch 10, 18.2 Unattended machinery to Pt 5, Ch 10, 18.3 Main, auxiliary and other boilers, as appropriate. Alternative arrangements which provide equivalent safeguards will be considered.

18.2.2 Where machinery is arranged to start automatically or from a remote control station, interlocks are to be provided to prevent start-up under conditions which could hazard the machinery.

18.2.3 Where machinery specified in this Section is required to be provided with a standby pump, the standby pump is to start automatically if the discharge pressure from the working pumps falls below a predetermined value.

18.2.4 Where a first stage alarm together with a second stage alarm and automatic shutdown of machinery are required in the relevant Tables of this Section, the sensors and circuits utilised for the second stage alarm and automatic shutdown are to be independent of those required for the first stage alarm.

18.3 Main, auxiliary and other boilers

18.3.1 Alarms and safeguards are indicated in Pt 5, Ch 10, 18.3 Main, auxiliary and other boilers 18.3.2 to Pt 5, Ch 10, 18.3 Main, auxiliary and other boilers 18.3.9 and Table 10.18.1 Main, auxiliary and other boilers: Alarms and safeguards.

Table 10.18.1 Main, auxiliary and other boilers: Alarms and safeguards

Item Alarm Note
Water level* Low Two water level sensors are to be provided, each to operate independently, and automatically to shut off the fuel oil to the burners and operate alarms,
see Notes 1 to 3 and 5
Water level 1st stage high —
  2nd stage high Where applicable, automatic closure of turbine steam inlet valves, see Pt 5, Ch 10, 18.2 Unattended machinery 18.2.4
Steam drum or superheater outlet pressure* High and Low —
Superheated steam temperature High —
De-superheated steam temperature* High —
Feed water or water forced circulation flow (if fitted) Low Fuel oil to burners to be shut off automatically, see Notes 5 and 6
Feed water pH Low When automatic dosing of feed water fitted
Feed water salinity High Fitted in boiler feed system
Feed water temperature Low When automatic temperature control fitted
Combustion air pressure* Low Fuel oil burners to be shut of automatically in operation
or not released during start up, see Note 5.
Purge sequences to be inhibited, see Pt 5, Ch 14, 3.1 Oil burning units 3.1.9
Fuel oil pressure* Low —
Fuel oil temperature or viscosity* High and Low Heavy oil only
Fuel oil atomising steam/air pressure Low —
Burner flame* Failure Each burner to be monitored. Fuel oil to burner(s) to
be shut off automatically, see Pt 5, Ch 14, 3.1 Oil burning units 3.1.11 and Pt 5, Ch 14, 3.1 Oil burning units 3.1.12 and Note 5
Flame monitoring device(s)* Failure See Pt 5, Ch 10, 18.3 Main, auxiliary and other boilers 18.3.7 and Note 5
Igniter power supply* Failure Each igniter to be checked before fuel oil is supplied
to burner, see Pt 5, Ch 10, 18.3 Main, auxiliary and other boilers 18.3.6 and Note 5
Forced draft fan* Power failure Fuel oil to burners to be shut off automatically.
Control using alternative arrangements is to remain
available, see Pt 6, Ch 1, 2.5 Control systems, general requirements 2.5.7
Air registers and dampers (including those in the uptake)* Not fully open Purge sequence to be inhibited, see Pt 5, Ch 14, 3.1 Oil burning units 3.1.9
Control system* Power failure Fuel oil burners to be shut off automatically. Control
using alternative arrangement is to remain available,
see Pt 6, Ch 1, 2.5 Control systems, general requirements 2.5.7
Uptake temperature High Where economiser and/or gas air heaters are integral with the boiler and also
for independent exhaust gas boilers/economisers, to monitor for soot fires.
See Note 7

Note 1. For dual-evaporation boilers, the primary circuit is to be fitted with two independent low water level detectors which will operate alarms and shut off the fuel oil to the burners automatically. The secondary circuit is to be fitted with one low water level detector which will operate alarms and shut off the fuel oil to the burners automatically. Additionally one high water level alarm is to be fitted on the secondary circuit which may be operated by the same detector as that provided for low water level detection.

Note 2. Only one independent system of low water level detection, alarm and automatic fuel oil shut-off need be fitted in the case of small forced circulation or re-circulation coiled water tube `package’ type boilers when evaporation is less than 2900 kg/hr or the heating surface is less than 100 m2.

Note 3. Where two level sensors are provided these may be used for other functions, e.g. high level alarm, level control, trip systems, etc.

Note 4. For boilers not supplying steam for propulsion or for services essential for the safety or operation of the ship at sea, only the items marked * are required.

Note 5. These safeguards are to remain operative during automatic, manual and emergency operation.

Note 6. For exhaust gas economisers/boilers requiring feed water or forced water circulation, the low flow alarm is to be fitted with provision to override the alarm if the exhaust gas economiser/boiler is to be operated in the dry condition. See also Pt 5, Ch 14, 6.2 Feed and circulation pumps 6.2.5.

Note 7. Alternatively, details of an appropriate fire detection system are to be submitted for consideration.

18.3.2 The following boiler services are to be fitted with automatic controls so as to maintain steady state conditions throughout the normal operating range of the boiler:

  1. Combustion system.

  2. Fuel oil supply temperature or viscosity, heavy oil only.

  3. Boiler drum water level.

  4. De-aerator water level, where applicable.

  5. Superheated steam pressure, where applicable.

  6. Superheated steam temperature, where applicable.

  7. De-superheated steam pressure, where applicable.

  8. De-superheated steam temperature, where applicable.

18.3.3 Safety systems and overrides are to comply with the requirements of Pt 6, Ch 1, 2.4 Safety systems, general requirements 2.4.8.

18.3.4 Burner controls are to be arranged such that light off is only possible at the minimum firing rate compatible with flame establishment. If ignition is set to occur at a fuel rich condition then the burner is to revert to the correct operating air/fuel ratio on establishment of a stable flame.

18.3.5 Where water level indicators are dependent upon an external power supply, the fuel oil supply to the burners is to be automatically shut off in the event of power or signal failure.

18.3.6 Arrangements are to be such that burner fuel oil valve(s) do not open:

  1. prior to completion of required warm up times for residual fuel oil; or

  2. when the power supply to the igniter has failed, as applicable; or

  3. until a pilot flame is established, as applicable; or

  4. prior to the completion of furnace purging, see Pt 5, Ch 14, 3.1 Oil burning units 3.1.7.

18.3.7 Arrangements for flame failure detection are to be provided with self-monitoring capabilities which ensure that the flame detector is not erroneously indicating the presence of a flame. In the event of failure being detected by these self-monitoring capabilities:

  • an alarm is to be activated;
  • in the event of loss of flame detection capability for a burner;
  • fuel oil to the burner is to be shut off automatically; and
  • an alarm is to be activated.

18.3.8 Where established as necessary by Pt 5, Ch 14, 3.1 Oil burning units 3.1.8, means are to be provided to prevent starting of the ignition sequence following multiple flame failures until completion of the identified lock-out period.

18.3.9 Following burner shutdown, the furnace is to be purged automatically for at least the required pre-purging time. In the event of shutdown due to activation of a required safeguard, this purging is to be manually initiated.

Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.