Procedures & Alarms

Milestones:

• Learning and Training Phase – Pre-Requisites for the start of operation:

1. Prepared Generators for use.
2. Test Run Gas Combustion Unit.
   • 2A: Start Gas Combustion Unit.
   • 2B: Increase GCU Output (2600 kg/h).
   • 2C: Turn Off Gas Combustion Unit.
   • 2D: Perform N2 Purging In GCU.
3. Open Required Valves For Line Up.

• Assessment Phase – Operational flow and Assessment:

4. Start Spray Pump In Cargo Tank 4.
5. Start LD Compressor When Required.
6. Obtained required temperatures inside the tanks.
   • 5A: Achieved -30°C in all three tanks.
   • 5B: Achieved -100°C in all three tanks.
   • 5C: Achieved -140°C in all three tanks.

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Actions During the Exercise:

Deviation From Exercise:

• After starting or resuming the cooldown, the user should not open any non-required valves or close any required ones. A caution message will be displayed to undo the previous action. Failure to correct it will result in exercise termination.

Reduce Temperature Drop Rate During Stage I:

• If the temperature drop exceeds -15°C: Caution message.
• If the temperature drop exceeds -20°C: Low-priority warning.
• If the temperature drop exceeds -25°C: High-priority alarm.
• Continued cooldown with caution alarm for 5+ minutes: Low-priority alarm.
• Continued cooldown with low-priority alarm for 5+ minutes: High-priority alarm.
• Failure to reduce the drop within 1 minute of high-priority alarm: Exercise termination.

Reduce Temperature Drop Rate During Stages II & III:

• If the temperature drop exceeds -11°C: Caution message.
• If the temperature drop exceeds -13°C: Low-priority warning.
• If the temperature drop exceeds -15°C: High-priority alarm.
• Continued cooldown with caution alarm for 5+ minutes: Low-priority alarm.
• Continued cooldown with low-priority alarm for 5+ minutes: High-priority alarm.
• Failure to reduce the drop within 1 minute of high-priority alarm: Exercise termination.

Close One Nozzle in Cargo Tanks Below 0°C:

• Remark issued when tank temperature reaches 0°C.
• Remark unresolved for 5+ minutes: Low-priority alarm.
• Low-priority alarm unresolved for 5+ minutes: High-priority alarm.
• Failure to close nozzle within 1 minute of high-priority alarm: Exercise termination.

Start LD Compressors:

• At 14 kPa pressure: Caution alarm to start one LD compressor. Failure to comply within 1 minute: Exercise termination.
• At 16 kPa pressure: Caution alarm to start the other LD compressor. Failure to comply within 1 minute: Exercise termination.

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Alarms & Remarks

Alarm Condition	Alarm Time	Alarm Level	Alarm Title	Alarm Description	Action
When prerequisite milestones for starting the cooldown are completed.	Before Starting Cooldown	Remark	Begin the cooldown process with a low flow rate.	Begin the cooldown with a low flow of 25 m³/h.
Tank Middle Temp <= 5°C	When particular tank middle sensor temperature reaches 5°C	Remark	Reduce Master Valve Opening In CT 1,2,3,4	Reduce the master valve opening to at least 25% For CT1 and 50% For CT2,CT3,CT4.
Valve not closed to required percentage, after receiving the remark	After 1 minute of receiving the remark alarm	Caution	Reduce Master Valve Opening In CT 1,2,3,4	Reduce the master valve opening to at least 25% For CT1 and 50% For CT2,CT3,CT4.
Tank Middle Temp <= 0°C	When particular tank middle sensor temperature reaches 0°C	Remark	Close One Nozzle In CT 1,2,3,4.	Close one spray nozzle in cargo tank 1 and continue cooldown.
One Nozzle Not Closed After Receiving the Remark(And Action Not Taken).	5 minutes after receiving the remark	Low Priority	Close One Nozzle In CT 1,2,3,4.	Close one spray nozzle in cargo tank 1 and continue cooldown.
One Nozzle Not Closed After Receiving the low priority (And Action Not Taken).	5 minutes after receiving the low priority	High Priority	Close One Nozzle In CT 1,2,3,4.	Close one spray nozzle in cargo tank 1 and continue cooldown.
whenever temperature drop exceeds the max level.	Whenever the drop is more than -17°C during stage 1 or 11°C during stage 2.	Caution	High Temperature drop in CT1,2,3,4.	High temperature drop in CT1,2,3,4, Adjust master valve CS103,203,303,403 or reduce the flow from shore.
Cargo Tank Pressure >= 14  kpa		Caution	Start LD Compressor	High pressure inside the tanks, start the LD compressor.
Cargo Tank Pressure >= 16 Kpa		Caution	Start Another LD  Compressor	Start another LD compressor.

Step By Step Procedure

• Learning and Training Phase – Pre-Requisites for the start of operation:

Preparing Generators for Use:

• Navigate to the PMS page through the side navigation.
• Turn on one of the three generators that are not currently running. (By default, one generator will already be running.)

Open all required valves for the line-up.

• Open the following required valves.

Valve	Status/Position
CS401	Open
CS701	Open
CS700	Open
CS103	25%
CS107	Open
CS108	Open
CS203	50%
CS207	Open
CS208	Open
CS303	50%
CS307	Open
CS308	Open
CS320	Open
CG100	Open
CG101	Open
CG200	Open
CG201	Open
CG300	Open
CG301	Open
CG400	Open
CG401	Open
CG901	Open
CG902	Open
CG914	Open
CG913	Open
CG940	Open
CG9105	100%
CG9106	100%

• • Access valves across various pages as necessary.

 

Test Run GCU:

• • Navigate to the Gas Combustion Unit (GCU) page via the side navigation.
  • Prepare and start the GCU.
  • Increase the GCU output to 2600 kg/h and maintain for a specific duration.
  • Stop the GCU and perform GCU purging.

• • Assessment Phase – Operational flow and Assessment:

Start Spray Pump in Cargo Tank 4:

• • Navigate to the Cargo Tank 4 page via the cooldown or side navigation.
  • To start the spray pump:
    • Open Valve CS401 to 25%-30%.
    • Open Valve CS400 to 95% or greater.
    • Ensure at least two generators are running.
  • Ensure Cargo Tank 4 Spray Pump Master Valve CS403 is closed or set to 5% or less.
  • Start the spray pump, then open the master valve and close the return valve to initiate cooldown.

Cooldown Process:

• • Adjust the pump flow rate to avoid exceeding drop rate thresholds.
  • Avoid deviations from required procedures or exceeding temperature drop limits.

Completion:

Achieve -130°C in all three tanks to complete the exercise.

Proper line up for CT cooldown at sea: