LNG Cargo ship

Summary

This video outlines the crucial procedures and precautions involved in handling liquefied natural gas (LNG) cargo aboard ships. It covers the potential hazards, such as gas leaks during loading, discharging, and maintenance operations. The video explains the construction of LNG cargo tanks, including membrane and Moss types, and the vital steps in cargo operations like inerting, gassing-up, and cooling down. Additionally, it discusses safety measures during loading, deballasting, and handling boil-off gases (BOG). The content emphasizes the importance of vigilance, safety training, and the correct use of protective gear to prevent accidents and ensure the safe transport of LNG.

Takeaways

• 😀 Understanding the hazards of liquefied gas cargo is crucial for the safety of the crew and environment during loading and discharging operations.
• 😀 Crew members need to be well-trained and take proper precautions, especially when working with liquefied gases in various ship areas like cargo tanks, compressor rooms, and ballast tanks.
• 😀 LNG carriers operate at extremely low temperatures (around -162°C) to transport liquefied natural gas safely.
• 😀 Different types of LNG cargo tanks include Membrane and Moss tanks, each with unique construction methods and safety features.
• 😀 Membrane tanks consist of thin layers of special steel, with additional insulation and a secondary barrier for added safety.
• 😀 Moss tanks use spherical aluminum tanks that can withstand varying pressures, and they have additional safety features like a drip tray to catch potential leaks.
• 😀 Prior to loading, cargo tanks must be inerted and cooled down to prevent dangerous conditions caused by the introduction of ambient temperature gases.
• 😀 Inert gas is used to displace oxygen and moisture from cargo tanks to reduce risks during the loading process.
• 😀 Gassing-up is performed to replace inert gas with warm LNG vapor to remove carbon dioxide and complete drying of the cargo tanks.
• 😀 Monitoring of tank pressures, managing boil-off gases, and ensuring the safe operation of compressors are critical during LNG loading operations.

Q & A

What are the main hazards when handling liquefied gas cargo on ships?

The main hazards include the presence of gas in the atmosphere during loading and discharging operations, gassing-up, and maintenance activities such as when pipelines or cargo pumps are opened. This poses risks of fire, explosion, and toxic exposure.

Why is training crucial for personnel handling LNG cargo?

Training is essential to ensure personnel understand the risks involved in handling LNG, are aware of safety protocols, and know how to react in emergencies to protect themselves and the environment.

What types of LNG cargo tanks are commonly used on ships?

The two main types of LNG cargo tanks are membrane tanks, which consist of thin layers of steel (INVAR), and Moss tanks, which use spherical aluminum tanks secured by an equatorial ring and supported by a central column.

What is the function of the INVAR steel in membrane-type LNG tanks?

INVAR steel is used in membrane-type LNG tanks because it has minimal expansion and contraction over a wide temperature range, ensuring the tank maintains structural integrity at cryogenic temperatures.

How does the inerting process work in cargo tanks?

The inerting process involves reducing moisture and oxygen content in the cargo tanks by introducing inert gas, usually nitrogen. This is done to prevent combustion and ensure the tanks are safe for LNG storage.

What is the importance of gassing-up the cargo tanks before loading LNG?

Gassing-up is important because it replaces inert gas with LNG vapor to remove carbon dioxide. This step ensures the cargo tanks are properly dried and prevents blockages caused by frozen CO2 when LNG is introduced.

What is the initial cool-down process before LNG can be loaded into cargo tanks?

The initial cool-down process involves pre-cooling the cargo tanks and lines using LNG from the shore terminal. This ensures the cargo system is at the correct temperature before LNG is loaded.

How is boil-off gas (BOG) managed during LNG loading operations?

Boil-off gas is managed by using a reliquification plant. The gas is compressed and cooled, and the condensed LNG is returned to the cargo tanks to maintain pressure and ensure safe storage conditions.

What safety precautions should be followed during LNG cargo operations?

During LNG cargo operations, personnel should be vigilant, wear protective suits and breathing apparatus when needed, and avoid direct contact with toxic vapors or liquids. Immediate decontamination should be done if exposed, and safety showers should be readily accessible.

What are the main components involved in LNG loading operations on ships?

The main components in LNG loading operations include loading arms, manifolds, spray nozzles for cooling down tanks, and compressors to handle boil-off gas. The operation also involves careful monitoring of tank pressures and ensuring that cargo is evenly distributed.