Modularization is now a familiar part of LNG project planning, particularly where labor costs and construction conditions, such as limited site access, can make a traditional stick-built approach difficult. However, choosing between the two approaches is not as straightforward as it might first seem.
Owners and engineers have to work out what can reasonably be built in the yard and what is better completed on-site. These choices also need to be made early, because they will determine everything from the size of the modules to the plant layout and the transport and installation considerations.
Once detailed engineering is under way, making any changes to modules or connections can lead to significant rework.
Deciding the strategy early
A project’s broader execution approach is normally considered during pre-FEED, while there is still enough flexibility to test different plant arrangements.
Labor availability is often a major factor. Fabrication yards can offer more predictable productivity than remote or high-cost construction sites. They also provide a controlled environment where more of the work can be completed before equipment is shipped.
Conditions at the final site are another condideration. Remote developments, for example, may have restricted access and limited accommodation for a large construction workforce. Brownfield sites present a different problem because new equipment has to fit around an operating plant, which could lead to limited access routes or crane positions. A module that is easy to assemble in a yard may be difficult to install if the site limitations aren’t considered from the outset.
CASE STUDY
Adapting Pluto for Scarborough gas
A good example of a modular application is the modifications project for the Pluto LNG Train 1 in Western Australia.
Located on the Burrup Peninsula near Karratha, Pluto Train 1 began producing LNG in 2012 using gas from the offshore Pluto area fields.
The Scarborough Energy Project will bring a new source of gas to Pluto from approximately 375 kilometers off the Western Australian coast. Around 5 million tonnes per annum will be processed through the new Pluto Train 2, with up to 3 million tonnes per annum processed through the existing Train 1 following the modifications, and once capacity becomes available.
Using Train 1 makes further use of an asset that has already been operating for more than a decade. However, it also creates an engineering challenge because the original train was designed around a different feed.
Pluto gas is relatively rich and typically contains higher levels of nitrogen. Scarborough gas is leaner, contains little ethane and has a different balance of heavier hydrocarbon components. Changes in feed composition affect how the gas must be treated before it enters the main liquefaction process.
KBR’s scope for the Train 1 modifications includes a new natural gas liquids (NGL) unit, nitrogen recycle compressor (NRC), Pluto gas custody metering and changes to supporting facilities. The work will allow Scarborough gas to be processed through the existing train.
Drawing the module boundaries
Once the process requirements had been established, the team needed to work out how the new equipment could be fabricated and transported.
The NGL extraction facility forms one process system, but it was too large to ship as a single structure. It was therefore divided between two modules that could be installed alongside one another and connected at Pluto.
For the wider Train 1 modifications project, three modules in total were fabricated at Laem Chabang in Thailand. Each was built up from a series of structural decks carrying equipment and pipework. The first deck lift involved a 340-tonne structure which would eventually form part of the largest completed module, weighing approximately 4,600 tonnes.
To be able to deliver this successfully, the fabrication yard needed to assemble and load the structure at dimensions suited to the shipping route and the vessel carrying it. The receiving site then needed enough access and lifting capacity to place it in its final position.
Module size also affects the amount of work left for the site team. Larger structures can reduce the number of connections required after delivery, although they place greater demands on transport and lifting. Dividing the equipment into smaller sections can make it easier to move, but this also means more assembly and testing at the plant.
The Pluto work used a combination of methods. Major process equipment and some supporting facilities were preassembled, while other elements could be constructed at site. Some pipework and connections are easier to complete in their final position, especially where they interact closely with existing systems.
We found the best balance by drawing up module boundaries that work for the process and the method of construction. Maximizing the amount fabricated offsite is not necessarily the best answer.
Preparing the operating plant
Off-site fabrication reduces the amount of construction carried out at the LNG facility, but there is still a substantial program of work at the receiving end.
Foundations and supporting steel must be ready before the modules arrive. Utilities and piping need to reach the correct connection points, while parts of the operating plant may have to be isolated so tie-ins can be completed safely.
This is especially important on a brownfield development where shutdown opportunities are limited and delays can affect production. A late change to an interface can lead to rework in the fabrication yard or during the turnaround.
The major Train 1 turnaround took place in the first half of 2026, lasted for more than a month, and involved over 1,500 personnel and contractors. It was a plant-wide program covering planned maintenance, modifications and upgrades to critical infrastructure, including tie-in work needed to prepare Train 1 for Scarborough gas.
The fabrication in Thailand and the work completed at Pluto needed to be closely coordinated. Although there was a benefit to building equipment off-site, success still depended on the on-site work, including foundations, interfaces and tie-in work being ready before modules arrived.
Applying the strategy elsewhere
Modular construction can be the practical choice where site labor is limited, costly or difficult to support, particularly on remote developments or in challenging weather.
In other locations, it may be better to build more of the plant on-site. The same plant may require different approaches in different areas. A large module may work well for one process unit, while elsewhere it could be difficult to transport or leave too much connection work to complete at the site.
Above all, modular strategy should be settled early while there’s still time to change to plant playout.
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