Safety regulations for LNG storage tank fueling process

When installing LNG storage tanks, the first thing to consider is hidden safety hazards. Due to the low temperature and flammability of LNG, once a leak occurs during the installation process, it will pose a major threat to the safety of ships and lives. According to relevant regulations, the installation of LNG fuel must meet the following requirements:

1) Ensure sufficient natural ventilation to prevent accumulation of flammable gases during the installation process, and it is necessary to pay attention to separation or structural protection from living spaces, cargo spaces and control stations;

2) The storage tank installation system should be arranged so that no gas will be discharged into the air during the installation;

3) A stainless steel drip tray should be installed below the LNG storage tank installation joint. If LNG leaks, it will be discharged out of the ship's side through the pipeline to prevent the hull structure from affecting the structural strength due to low temperature brittleness;

4) The pressure vessel installation system should be equipped with remote pressure, liquid level monitoring and alarm functions, and can realize automatic shutdown; 5) A manual shut-off valve and a remote control shut-off valve, or a combination valve of manual operation and remote control should be installed in series near each shore of the installation pipeline, and can be installed at the control position of the fuel installation operation and / or other Operate the remote control valve in a safe position;

6) At the end of the installation, measures should be taken to discharge LNG from the storage tank filling pipeline;

7) Installed joints should not face the entrances of living spaces, machinery spaces, control stations, etc. or air inlets to prevent gas from entering these areas;

8) During the installation process, doors and windows and air inlets on both sides of the superstructure or deckhouse should be closed.
 
The requirements of Articles 6) and 7) can be met in practice. Because different lengths of pipes are required during the installation process, a certain amount of residual liquid will inevitably remain in the pipes after the pressure vessel is filled with gas. At present, the treatment of residual liquid in the process of fuel installation is very mature. Generally, compressed air is used to blow the residual oil in the pipeline into the tank of the receiving ship after stopping the pump. For safety reasons, LNG needs to avoid contact with the air. After the LNG is filled, the pipeline can be purged with nitrogen to achieve the purpose of residual liquid treatment.