Floating LNG puts a gas plant, LNG tanks and a loading terminal on one hull, so gas can become LNG right above an offshore field. As a result, remote gas can reach buyers even where a pipeline to shore is not possible.
Floating LNG (FLNG) is a vessel that cleans, cools, stores and offloads natural gas at sea. The process logic matches an onshore plant, but space, motion and offloading change. Use the checklist below to review a project, then pick one adjacent skill to explore.
Picture an engineer who has run an onshore gas plant for years, and whose next project floats. What changes, and what stays the same?
This guide follows that question. It starts with how FLNG works, moves on to what changes at sea and where projects get risky, and ends with a ten-point review checklist and skills to explore next. The examples begin in Southeast Asia, yet the ideas apply across the region and beyond.
It suits process, marine, terminal, safety and commercial professionals who are new to floating LNG, as well as managers who review projects.
Key takeaways
- An FLNG unit treats, liquefies, stores and offloads gas on one hull.
- The process logic stays familiar, while space, motion and offloading change.
- The plant fits into roughly a quarter of an onshore plant’s area, so layout drives safety.
- Project risks cluster around cost, weather, track record and LNG prices.
- A ten-point checklist and a skills map help you decide your next step.
Key terms in everyday words
Why would anyone build floating LNG?
Some gas fields are remote or small, so a pipeline and an onshore plant may not make sense. Floating LNG offers another route, because the plant goes to the field instead.
How does floating LNG work, step by step?
As Figure 1 shows, gas moves through five stages between the field and the carrier. The list below spells out each one.
- Gas arrives from the field through risers.
- Pretreatment removes impurities from the gas.
- Liquefaction cools the gas into LNG.
- The hull stores the LNG near −162°C in its tanks.
- Carriers collect the LNG, and often LPG and condensate, at the offloading point.
Four building blocks of an FLNG unit
Coming from gas processing? The treating and cooling steps will feel familiar, so Upstream Gas Conditioning and NGL Recovery and Gas Treatment and Sulphur Recovery are natural ways to refresh the pretreatment side.
What changes when the plant floats?
Three things change at once: space, motion and weight. Each one touches safety, so designers treat them together.
Those Lloyd’s Register slides also say membrane tanks may be vulnerable to sloshing damage when part full, whereas Moss tanks have no barred fill ranges.
Floating Liquefied Natural Gas (FLNG) – Design and Technology
Covers LNG behaviour on floating structures and the process from well fluids to exported LNG.
Evolving Designs and Construction Techniques of Floating LNG Terminals – FSUs and FSRUs
Covers cryogenic containment, sloshing, hull and mooring, swivels, fluid transfer and ship-to-ship transfers for FSUs and FSRUs.
How does offloading work at sea?
Next comes the handover. Carriers must connect to a moving unit, so the weather sets the pace.
LNG Supply Chain, Regasification, and Terminal Operations
Covers LNG carrier systems, ship-to-ship transfers, FSU and FSRU offloading, and marine and port operations.
Where is floating LNG used in Southeast Asia and beyond?
In Malaysia, PFLNG Satu has a capacity of 1.2 million tonnes per annum (mtpa). It loaded its first cargo in April 2017 at the Kanowit field, offshore Sarawak, and later moved to the Kebabangan field off Sabah. PFLNG Dua, with 1.5 mtpa, sits over the Rotan field and delivered its first cargo in March 2021.
Indonesia’s floating example sits on the import side: the Nusantara Regas Satu FSRU in Jakarta Bay supplies gas to power plants, with a design capacity of up to 3 mtpa. Further afield, the Prelude FLNG off Western Australia is 488 m long and produces 3.6 mtpa of LNG, 1.3 mtpa of condensate and 0.4 mtpa of LPG.
Whatever the country, every project faces waves, cold liquid and tight space, so these ideas apply across Southeast Asia and beyond.
Which FLNG project risks should you watch?
Technical and safety risks
Project and commercial risks
Covers LOPA, independent protection layers and the functional safety lifecycle for high-hazard facilities.
EPCIC Contract Drafting and Management: With Essential Elements of International Contract Laws
Covers contract formation, consortium risks, variation claims and dispute resolution in international EPCIC projects.
Use it: a ten-point floating LNG project review checklist
Use this list in design reviews, in onboarding or before an interview. It is general guidance, so adapt it to your own project and standards.
- Confirm that hazardous modules have enough gaps, because space is tight.
- Review the hull and topsides interface, since heavy modules load the hull.
- Test the tank design against partial filling, because sloshing and fatigue depend on it.
- Verify process plant reliability on a moving hull, where little line pack is available.
- Set the offloading method and its wave limit early, because they decide the downtime.
- Study the site’s weather data before choosing the mooring, heading and turret.
- Understand the gas composition, since it shapes complexity from the start.
- Plan the classification route early, because floating terminals follow class guides.
- Ask about local expertise and emergency response, which may run thin in emerging markets.
- Stress-test cost, schedule and market assumptions, because early projects ran over and prices can fall.
What else can you explore? Skills that travel with floating LNG
Floating LNG skills travel well. The same ideas appear in other cold-cargo, floating and process work, so many people add one adjacent topic after the basics. Figure 4 maps common starting points to topics worth exploring.
Adjacent paths by starting role
FLNG and cross-skilling courses to explore
Each course has a button to its own page, with current dates.
Where to go next
Build FLNG skills in your team
Floating LNG projects combine process, marine and commercial work, so shared knowledge helps teams decide well. Browse the full calendar, or ask about training for your own team at your chosen venue and dates.
For further reading, see the PFLNG Satu release, the ABS guidance note and the Prelude report.
This article is for general information only. Please follow your own procedures, standards and local regulations for any real operation.
FAQ
Floating LNG, or FLNG, means a vessel moored above an offshore gas field that cleans, liquefies and stores natural gas, and then loads the LNG onto carriers. In other words, it puts a gas plant, LNG tanks and a loading terminal on one hull.
An FLNG unit must fit its equipment into roughly a quarter of the area of an onshore plant, and it must work while the hull moves with the waves. As a result, layout, safety, sloshing in partly filled tanks and offloading at sea need special design attention.
An FLNG unit produces LNG at the gas field. In contrast, a floating storage and regasification unit (FSRU) receives LNG and turns it back into gas, while a floating storage unit (FSU) stores LNG and passes it on to other ships.
The main technical risks are tight space with fire and blast hazards, heavy topsides loading the hull, long years on station in harsh weather, and cold liquid close to critical structures. In addition, project risks include a complex supply chain, site and gas composition choices, classification approval, and contracts and cost control.
Yes. Malaysia has built two FLNG units, PFLNG Satu (1.2 mtpa) and PFLNG Dua (1.5 mtpa). Indonesia has used the Nusantara Regas Satu floating import terminal in Jakarta Bay since about 2012. The same ideas apply across the region and beyond.
Process engineers can start with Floating Liquefied Natural Gas (FLNG) – Design and Technology and Upstream Gas Conditioning and NGL Recovery. Marine teams can add the FSU and FSRU course, and terminal teams can add LNG Supply Chain, Regasification, and Terminal Operations. Safety and commercial teams can add LOPA, LNG commercial and contract courses. Please check each course page for current dates.
