Procedures & Alarms

Milestones

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

1. Prepare HD Compressors And Generators For Use.
2. Connect Manifold Arm L3 and V.
3. Open Required Valves for Line Up.

 

• Assessment Phase – Operational flow and Assessment:

4. Start One HD Compressor.
5. Achieved Required Temperatures In All Tanks.

• Achieved -30°C Temperature In All Tanks.
• Achieved -100°C Temperature In All Tanks.
• Achieved -130°C Temperature In All Tanks.

Exercise Actions and Warnings

1. Close One Nozzle in Cargo Tanks with Temperature Below 0°C:
   • When a tank’s temperature reaches 0°C, the user must close one of the spray nozzles in that tank.
   • If not resolved within 5 minutes, a low-priority alarm will be issued. If unresolved for another 5 minutes, a high-priority alarm will trigger. Failure to correct this within 1 minute of the high-priority alarm will result in termination of the exercise.
2. Starting HD Compressors as Per Requirement:
   • When the tank’s pressure reaches 14 kPa, an alarm will be issued to start one of the HD compressors. Failure to do so within 1 minute will terminate the exercise.
3. Increasing HD Compressor Veins:
   • When the tank’s pressure reaches 14.5 kPa, an alarm will instruct the user to increase the veins of the running HD compressor. Failure to do so within 1 minute will terminate the exercise.
4. Starting Second HD Compressor:
   • If the pressure reaches 15 kPa, the user will receive an alarm to start the second HD compressor. If the veins of the first HD compressor have not been reduced to 0%, the second compressor cannot be started. Failure to start the second compressor within 1 minute will terminate the exercise.
5. Increasing Both HD Compressors Veins:
   • When the tank’s pressure reaches 15.5 kPa, an alarm will instruct the user to increase the veins of both HD compressors. Failure to do so within 1 minute will terminate the exercise.

6. Deviation from Exercise

   • Important: After starting or resuming the cooldown process, do not open non-required valves or close any required valves.
     • A caution message will appear if this happens, instructing the user to undo the action.
     • If the user fails to correct it, the exercise will be terminated.

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 >= 14kpa		Caution	Start HD Compressor	High pressure inside the tanks, start the hd compressor.
Cargo Tank Pressure >= 14.5 Kpa		Caution	Increase HD Compressor Veins	High pressure inside the tanks,increase the hd compressor veins to maintain pressure.
Cargo Tank Pressure >= 15Kpa		Caution	Start Another HD Compressor	Start another hd compressor, reduce the veins of HD Compressor 1 before starting another hd compressor.
Cargo Tank Pressure 15.5 Kpa		Caution	Increase The Veins Of Both The HD Compressors	High pressure inside the tanks, increase the veins of both hd compressors to maintain pressure.

Step By Step Procedure

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

Prepare Both HD Compressors and Required Generators for Use

• Generators: The HD Compressor requires at least two generators to be operational.
  1. Navigate to the PMS page either through the side navigation or by clicking the “number of generators running” indicator on the HD Compressor page.
  2. Once on the PMS page, turn on one of the three generators that are not running (Note: One generator will already be running by default).
• After the required number of generators is running, the user must:
  1. Visit each of the two HD screens.
  2. Start the Aux LO Pump and switch ON the Heater for the Oil Reservoir.
  3. Open the inlet and outlet valves for the HD compressors.

 

Connect Manifold Arm Spool Piece

• Locate the highlighted manifold arm positioned above the liquid manifold.
• Click on the highlighted arm to initiate the connection process.
• Once all required arms are connected, the milestone will be marked as completed.

 

Complete the Line-Up by Following the Required Steps

1. Cargo Tank Vapour Valves:

Position	Description	Valve
Open	No.1 cargo tank vapour valves	CG100, CG101
Open	No.2 cargo tank vapour valves	CG200, CG201
Open	No.3 cargo tank vapour valves	CG300, CG301
Open	No.4 cargo tank vapour valves	CG400, CG401

2. Vapour Line to No.1 Vent Mast and Regulating Valve:

Position	Description	Valve
Open	Vapour line to No.1 vent mast valve	CG701
Close & Auto	No.1 vent mast regulating valve	CG702

3. Spray Line Valves:

Position	Description	Valve
Open	No.3 port cooling down valve	CS031
Open	Spray line crossover isolation valve	CS072
Open	Spray line isolation valves	CS700, CS701

4. Cargo Tank Spray Line Valves:

Position	Description	Valve
Open	No.1 cargo tank spray master valve	CS103
Open	No.1 cargo tank spray rail valves	CS107, CS108
Open	No.2 cargo tank spray master valve	CS203
Open	No.2 cargo tank spray rail valves	CS207, CS208
Open	No.3 cargo tank spray master valve	CS303
Open	No.3 cargo tank spray rail valves	CS307, CS308
Open	No.4 cargo tank spray master valve	CS403
Open	No.4 cargo tank spray rail valves	CS407, CS408
Open	No.3 cargo tank spray block valve	CS320
Open	No.4 cargo tank spray block valve	CS420

5. HD Compressor Valves:

Position	Description	Valve
Open	No.1 HD compressor inlet valve	CG903
Open & Auto	No.1 HD compressor surge valve	CG1021
Open	No.1 HD compressor outlet valve	CG915
Open	No.2 HD compressor inlet valve	CG904
Open & Auto	No.2 HD compressor surge valve	CG1022
Open	No.2 HD compressor outlet valve	CG916
Open	Compressor line valve to vapour manifold	CG900

6. Vapour Line Valves:

Position	Description	Valve
Open	Vapour line valve to HD compressors	CG704
Open	Port vapour manifold ESD valve	CG071

7. Manifold Valve:

Position	Description	Valve
Open	No.3 port cargo liquid manifold ESD valve	CL031

 

Note: The user must ensure that the above valves are set correctly across the various pages for proper line-up.

Note: Valve CG702 is only available in the Cargo System page.

• Assessment Phase – Operational flow and Assessment:

Starting the Cooldown Process

• Set the flow rate from shore and begin the cooldown process.
• If the drop rate exceeds the maximum allowed for the given flow rate and spray nozzle valve combination, alarms will be triggered.
• If the drop rate is set too low, it will prevent achieving -140°C within the given duration.

HD Compressor Requirements

• Pressure Reaching 14 kPa:
  • An alarm will instruct the user to start one of the HD compressors.
  • The compressor must be properly prepared before starting.
• Pressure Reaching 14.5 kPa:
  • An alarm will instruct the user to increase the veins of the running HD compressor.
• Pressure Reaching 15 kPa:
  • An alarm will instruct the user to start the second HD compressor.
  • The veins of the first HD compressor must be reduced to 0% before starting the second compressor.
• Pressure Reaching 15.5 kPa:
  • An alarm will instruct the user to increase the veins of both HD compressors.

 

Achieve Required Temperatures Inside the Tanks

• Achieve -30°C in all four tanks.
• During Stage I cooldown:
  • If the temperature drop exceeds 17°C/h, a caution message will be shown, instructing the user to reduce the drop rate.
  • If the temperature drop exceeds 20°C/h, a low-priority warning will be issued.
  • If the temperature drop exceeds 25°C/h, a high-priority alarm will be triggered. This alarm will remain active for 5 minutes. If the user continues the cooldown with a caution alarm, the respective tank valves will lock. The valves need to be reset to continue.
  • Each cargo tank valve can lock twice during the exercise. If the valve locks for a third time, the exercise will be terminated.
• Achieve -100°C and -130°C in all four tanks.
• During Stage II & III cooldown:
  • If the temperature drop exceeds 11°C/h, a caution message will be shown.
  • If the temperature drop exceeds 13°C/h, a low-priority warning will be issued.
  • If the temperature drop exceeds 15°C/h, a high-priority alarm will be triggered. Same procedure as above for valve locking.

 

Completion of Exercise

• Once the user achieves -130°C in all four tanks, the exercise is completed successfully.

 

Proper line up for cargo tank cooldown from shore: