This operation is carried out after the liquid line cool-down has been completed. The user is tasked with performing the initial two hours of the LNG loading operation. During this operation, the user ramps up the flow from the shore and loads LNG into the cargo tanks in stages. The goal is to increase the flow from 0 to 10,000 m³ per hour while ensuring that the tank levels are staggered so that all tanks do not reach their full capacity at the same time.

LNG is loaded via the loading manifolds to the liquid header and then to each tank filling valve. The boil-off and displaced vapour leave each tank via the vapour domes to the vapour header. The vapour is initially free-flowed to shore via the vapour crossover manifold and, as tank pressure rises, one compressor is brought into operation to increase the gas flow to shore and limit the vapour main and hence cargo tanks’ pressure.

De-ballasting is undertaken at the same time as cargo loading, and the de-ballasting sequence is arranged to keep the vessel within the required limits of draught, trim, stress, and stability. If necessary, the flow of nitrogen to the inter-barrier spaces is increased to maintain a positive pressure in these spaces during the completion of cool-down and the start of loading. This is often achieved by increasing the pressure in the inter-barrier spaces before starting the operation.

The cofferdam heating system is put into operation well in advance and before arrival at the terminal; e.g. when low atmospheric temperature on arrival at the port system must be set in operation well in advance. The open sea system is always in operation, to maintain steady temperatures at cofferdams and dome spaces.

On completion of loading, the liquid header and other liquid pipes are drained usually to the aft cargo tank. The liquid remaining in the inclined part of the liquid manifolds is pushed in board using N2 pressure from shore and the loading arms are then purged and disconnected.

Preparations for Loading
Loading is commenced after the cool-down of the cargo piping with one of the shore pumps. This can be done by opening the ESD and double shut valves, allowing liquid to flow directly into the main liquid lines or by opening the ESD valve and crossing over into the smaller spray line and then back to the liquid line inboard of the double shut valve. The latter system has the advantage of restricting the flow of liquid from the shore as it passes into the smaller-diameter spray line. In either case, the liquid flows initially to the end tanks (1 and 4) and then to all tanks.

Once the ship and shore pipelines have cooled down (about 90 minutes), open all tank filling valves and commence loading at the agreed rate. Loading rates are usually increased (ramped up) in agreed increments to the maximum loading rate in about one hour or as per the pump-up plan.

As the loading rate increases, it is important to monitor the evolution of the tank pressures and to start one or two HD compressors in order to limit the pressure in the tanks. If the compressors are unable to cope with the volume of boil-off and displaced gas, it will be necessary to reduce the loading rate.

During the time of cooling down of the piping and the start of loading, it is important to patrol the whole deck area to monitor for all potential cargo leaks. All leaks, even the smallest one, must be corrected immediately even if this requires slowing down or even stopping the loading.

Precautions during the early stages of loading
The initial loading rate should be at the terminal minimum rate or at a rate, which is within the capabilities of the vessel’s vapour control equipment. The rate can then be increased gradually to the maximum agreed rate where the tank pressures can be maintained steady at a working level sufficiently below the relief valve setting;

The boil-off and displaced vapour are initially free-flowed to shore via the vapour crossover manifold and, as tank pressure rises, one HD compressor is brought into operation to increase the gas flow to shore. Under these conditions, the loading rate is governed by the rate at which the terminal can handle the vapour;

In the early stages of loading, the cargo tanks and/or the incoming cargo liquid may be warm and generate vapour in excess of the vapour return line capacity. A close watch must be kept on cargo tank pressures;

The loading rate must be reduced in good time before nearing the relief valve set pressures;
LNG High Duty Compressors should be immediately available with enough electrical power available to ensure immediate starting. HD compressors should be cooled down and the lube oil warmed up prior to normal use.

If reducing the rate or the use of High Duty Compressors does not control the pressure rise, the loading must be stopped immediately and the terminal notified. In some occasions when the shore/ terminal cannot control the BOG return, then and after agreement Gas burning shall be commenced.

Loading Operation
The terminal will connect the shore loading and vapor arms to the vessel’s manifold. The ship-to-shore Emergency Shutdown (ESD) cable will be connected and the integrity confirmed. The loading and vapour arms and connections to the vessel will be leak tested to the agreed pressure and checked for leaks. A warm ESD and cold ESD test will be carried out complying with the agreed procedure.
LNG is loaded via the liquid crossover manifolds to the cargo liquid line and then to each cargo tank branch and filling valves. The boil-off and displaced vapour leave each cargo tank via the gas domes to the cargo vapour line. The vapour is initially free-flowed to the terminal via the vapour crossover manifold. As the tank pressure rises, one or both of the HD compressors are brought into operation to increase the gas flow to the terminal and limit the cargo tank pressure. Deballasting is undertaken at the same time as cargo loading and the deballasting sequence is arranged to keep the vessel within the required limits of draught, trim, stress and stability. Deballasting should be completed before the end of loading.

The nitrogen pressurisation system for the insulation spaces would normally be in automatic operation and lined-up to supply the additional nitrogen necessary to compensate for the contraction from cooling the tanks.

The cofferdam heating system should be in operation and working correctly. On completion of loading, the cargo liquid line and other liquid lines are drained to the No.4 cargo tank. The liquid remaining in the inclined part of the liquid manifolds is pushed inboard using nitrogen pressure from the terminal, and the shore arms are then purged and disconnected.

Allowance must be made when topping off the No.4 tank for cargo arms and lines draining back to this tank to prevent overfilling the tank.

It is important to remember:

• Request terminal control to start loading at the pre-arranged reduced rate.
• Initially, BOG returned to Shore by free flow method. As tank pressure increases start the first HD compressor to return Gas at Shore. But before starting inform the terminal and the E/R.
• There is a great possibility to put in service the 2nd HD compressor for the first hours of loading until the pressure stabilize in normal operating levels.
• Providing that no problems occur (such as cargo leakages, HD compressor working condition, N2 supply etc.) request the terminal to increase the loading rate up to maximum over the pre-arranged time scale.
• Start the second HD compressor as boil-off generation begins to exceed the capacity of the first HD compressor in the service unit. Again, inform terminal control and the E/R before starting.
• Adjust loading valve opening to provide the desired stagger between the tanks.
• Attention to be given to the notice(s) given to terminals regarding increased/reduced loading rates.

Exercise Overview:

1. Initial Setup:

The exercise begins with the setup of necessary systems and machinery, including Starting the required equipment. Configuring various systems. Lining up the valves to direct LNG into the cargo tanks.

2. Assessment Process:

• The assessment begins when the user presses the “Start Loading” button.
• The user must ramp up the flow from the shore in increments of 1,000 m³ per hour, ultimately achieving a total flow of 10,000 m³ per hour.
• During the assessment, the user must manage the loading process carefully to ensure that the tank levels are staggered. This means monitoring and adjusting the flow to ensure that no two tanks are filled simultaneously.

3. Completion Criteria:

• The exercise progresses as the user successfully completes milestones, including:
• Correctly increasing the flow rate.
• Achieving the required staggered tank levels.
• The exercise is considered complete once the user has successfully achieved all the milestones, ensuring that the correct procedures were followed for flow rate increase and tank staggering.

4. Evaluation:

• The user’s performance is assessed based on their ability to respond to various remarks, Cautions, and alarms that occur during the course of the exercise.

Learning Objectives for the Exercise

Participants will be able to effectively demonstrate the process of loading cargo tanks on LNG ships, understanding the necessary safety protocols, operational procedures, and the significance of maintaining safe and efficient loading operations.

Key Components:

1. Understanding the Loading Process:
   • Explain the purpose and importance of loading LNG into cargo tanks.
   • Identify key factors that affect loading operations, including temperature, pressure, and flow rates.
2. Operational Procedures:
   • Detail the step-by-step process for loading cargo tanks, including:
     • Pre-loading checks and preparation of cargo tanks and systems.
     • Connecting loading arms or hoses to the cargo tanks.
     • Starting the loading operation while monitoring flow rates and pressures.
   • Explain how to manage vapor return and maintain pressure within safe limits during loading.
3. Monitoring and Verification:
   • Demonstrate the use of monitoring systems for temperature, pressure, and flow rate throughout the loading process.
   • Describe how to confirm that cargo tanks are being loaded correctly and safely.
4. Documentation:
   • Record all activities during the loading process, including loading rates, final quantities, and any anomalies encountered.
   • Prepare a report summarizing the loading operation and compliance with safety regulations.
5. Practical Demonstration:
   • Simulate the loading process in a controlled environment or through hands-on training exercises.
   • Role-play scenarios to address potential challenges or deviations from the procedure.

Assessment Criteria:

• Ability to articulate the significance of the loading process for LNG cargo tanks.
• Accurate execution of the loading procedure and effective monitoring.

By achieving this objective, participants will gain the knowledge and skills necessary for safely and efficiently loading cargo tanks on LNG ships, ensuring successful and secure LNG operations.

Loading Ramp up and Staggering – HD Compressor Loading Prep and ESD

Loading Ramp up and Staggering – HD Compressor CTS set up

Loading Ramp up and Staggering-HD Compressor

Loading Ramp up and Staggering-Line up and Manifold

Loading Ramp up and Staggering- Operations and Assessment

Milestones

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

1. Configure The Correct Setting For The ESD.
2. Prepare Both HD Compressors and Generators for use.
3. Run a custody transfer print-out for official tank gauging.
4. Connect Manifold Arm L2,V,L3 and L4.
5. Opened required valves for line up.

• Assessment Phase – Operational flow and Assessment:

6. Ramp up completed.
7. Ran Both HD compressors when required.
8. Staggering achieved for all tanks.

• The difference of 40cm achieved between CT1 and CT2.
• The difference of 20cm achieved between CT2 and CT4.
• The difference of 20cm achieved between CT4 and CT3.

Actions taken during the exercise

Failure Conditions for Crossover Pressure and Instantaneous Rate

• If the crossover pressure reaches 4 bar, the user will be warned to increase the filling valve openings.
  • If the pressure reaches 5 bar, the exercise will be terminated.
• If the instantaneous rate of a tank reaches 4000 m³/h, the user will be warned to increase the filling valve openings.
  • If the rate reaches 5000 m³/h, the exercise will be terminated.

Emergency Shut down during operation

During the loading process, a leak may be detected in the liquid line L2. In such a case, the user should navigate to the ESDS System page and activate the ESD Manual Push Button to trigger an emergency shutdown. After resetting the system, the user can proceed with resuming the loading process.

Alarms & Remarks

Step By Step Procedure

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

1. Configure the Correct Settings for the ESD

To ensure the ESD system is ready:

1. 1. Visit the ESD System page.
   2. Set the following switches:
      • Ship / Shore Link: USE
      • Pneumatic Selector: BYPASS
      • ESD Port Selector: LOADING
      • ESD Mode: NORMAL

Check that the correct lights and indications are ON before moving to the next step.

Milestone 1 (M1)

2. Prepare Both HD Compressors and Required Generators for Use

• • The HD Compressors require at least two generators to be operational. Navigate to the PMS page via the side navigation or by clicking the “Number of Generators Running” indicator on the HD Compressor page (High Duty Compressor 1 or 2 in the side navigation).
  • Turn on one of the three generators that is not currently running. By default, one generator will already be running.
  • Once the required generators are running, visit each HD Compressor screen and perform the following:
    • Start the Aux LO Pump.
    • Switch ON the Heater for the Oil Reservoir.
    • Ensure the inlet and outlet valves on both HD compressors are open.

3. Run a CTS Report Setup and Activate CTS Status for Official Tank Gauging

• • Navigate to the CTS Main page via the side navigation.
  • Set the ship mode to harbour and filter mode to normal.
  • Fill in the required details in the report data and select loading in the CTS Report under Report and Setup.

4. Connect Manifold Arm Spool Pieces

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

5. Complete the Lineup by Following the Required Steps

1. 1. Set the Cargo Tank Vapour Valves:
      • Open CG100, CG101 for No.1 cargo tank vapour.
      • Open CG200, CG201 for No.2 cargo tank vapour.
      • Open CG300, CG301 for No.3 cargo tank vapour.
      • Open CG400, CG401 for No.4 cargo tank vapour.
   2. Set the Vapour Line to No.1 Vent Mast:
      • Open the vapour line to No.1 vent mast (CG701).
      • Set CG702 to Auto (No.1 vent mast regulating valve).
   3. Set the Cargo Tank Liquid Valves:
      • Open CL107, CL207, CL307, CL407 for cargo tank liquid branch valves.
      • Open CL100, CL200, CL300, CL400 for cargo tank liquid filling valves.
   4. Set the HD Compressor Valves:
      • Open CG903, CG915 for No.1 HD compressor inlet and outlet valves.
      • Set CG1021 to Auto for No.1 HD compressor surge valve.
      • Open CG904, CG916 for No.2 HD compressor inlet and outlet valves.
      • Set CG1022 to Auto for No.2 HD compressor surge valve.
   5. Set the Vapour Line Valves:
      • Open CG704 for the vapour line to HD compressors.
      • Open CG900 for the compressor line to the vapour manifold.
      • Open CG071 for the port vapour manifold ESD valve.
   6. Set the Cargo Liquid Manifold Valves:
      • Open CL023, CL033, CL043 for the cargo liquid manifold double-shut valves.
      • Open CL021, CL031, CL041 for the port cargo liquid manifold ESD valves.

After ensuring that the valves are correctly set as per the above list, the lineup will be complete.

Note: Valve CG702 is only available on the Cargo System page and Cargo Tank No.1.

• Assessment Phase – Operational flow and Assessment:

6. Start Loading and Complete Ramp-up

1. 1. Increase the Ship Rate to 1000 m³/h to enable the “Start Loading” button.
   2. Once clicked, the cargo tanks will begin loading LNG at 1000 m³/h.
   3. During the ramp-up process, a new ship rate will be available every six minutes. The user must update the ship rate to the new rate within one minute.
   4. If the rate is not updated as required, the exercise will be terminated.

7. Start HD Compressors as per Exercise Requirement

1. 1. When the Cargo Tank Pressure reaches 14 kPa, the user will receive an alarm to start one of the HD compressors.
      • The user must start HD Compressor 1 or HD Compressor 2 from their respective pages.
   2. When the pressure reaches 14.5 kPa, the user will receive an alarm to increase the veins of the running HD compressor to maintain the Cargo Tank pressure.
   3. When the pressure reaches 15 kPa, the user will receive an alarm to start another HD compressor.
      • The user must decrease the veins of the running HD compressor to ZERO in order to start the other HD compressor.
   4. When the pressure reaches 15.5 kPa, the user will receive an alarm to increase the veins of both HD compressors to maintain the pressure.

8. Achieve Staggering Between Cargo Tanks

1. 1. Achieve a 40 cm Difference between CT1 and CT2.
   2. Achieve a 20 cm Difference between CT2 and CT4.
   3. Achieve a 20 cm Difference between CT4 and CT3.

The user should adjust the filling valves to achieve the required level differences between the cargo tanks. Each tank level should be staggered to make the topping-off process easier.

Proper line up for loading ramp up and staggering: