An LNG terminal often needs a marine infrastructure known as the LNG jetty. LNG jetty construction is a highly-specialised project that demands the experience and expertise of professional jetty planners and builders.
Knowing more about an LNG Jetty Construction
A construction that projects pipelines from a terminal onshore out and over the water is the simple explanation of an LNG jetty. LNG jetty construction consists of mooring and breasting dolphins, access roads, loading arms, piles, pipelines, and a trestle.
This type of jetty construction requires both marine and onshore environment interventions, is time-consuming, and is very expensive. However, constructing the jetty creates an exemplary LNG transfer connection between an onshore terminal and a berthed vessel.
The length of the jetty varies depending on the local conditions and requirements. The jetty can be several miles or just a few metres long. Some of the varied terminal configurations for an LNG jetty construction include:
- Onshore terminals
- FSRU or floating storage regasification units
- FRU or floating regasification units
- FSU or floating storage units
Multiple aspects and components of an LNG Jetty construction
Dredging
The process used in shallow waters to enhance accessibility to marine vessels is known as dredging. The loading condition and draught of the ship require a certain water depth to prevent it from running aground.
The depth standard of LNG jetties typically has 10 to 15-metre draughts. Yet, the addition of a safety margin is always added for waves and tides.
Jetty piling
A seabed being set with deep foundations is the process known as piling. The topside of the jetty is supported by the deep foundations. Driving the piles deep into the seabed is important for the jetty to be able to withstand all types of rough conditions.
Transfer line
Safety systems, associated valves, and loading arms placed on the jetty serve as the pipelines or transfer lines for LNG transfers. The interface between the LNG carrier and the pipelines is the loading arms. The arms are connected to the pipeline’s carrier manifold to shore. Towards the vessel manifold is arms fitted at the end with ERC or emergency release couplings. In cases of emergencies, the separation of the jetty pipelines is a crucial safety measure.
Mooring and breasting dolphins
Marine constructions that rise above the levels of water are called dolphins. The extra mooring points provided by the dolphins help to extend the ship’s berth. A T-shape is typically made by dolphins when combined with the jetty head and trestle.
The functions of breasting dolphins include:
- Act as mooring points to restrict the longitudinal motion of the vessel
- Take off some of the berthing loads
The functions of the mooring dolphins include:
- Often used to restrict a berthing vessel’s transverse motion
- Serve as the mooring lines
Mooring line handling becomes an easier task with the connection of the walkways to the dolphins.
Topside of the jetty
The structure that is supported by piles and lies above water is known as the jetty’s topside. The connection between the jetty head and onshore facilities usually makes the topside have a trestle with gas pipelines. The loading arms on the jetty head are used to load or discharge LNG from and to the LNG carrier.
Jetty construction projects are expensive and time-consuming projects. Activities such as getting governmental approval, feasibility studies, investment decisions, and more can potentially take around 2 to 5 years.
