In the Petrofac world, modularisation is nothing new.

Rather than building everything onsite, it often makes sense to do some prefabrication offsite in a workshop environment. It saves on space, it enables production to be scaled-up, and it is often easier to achieve the necessary quality standards. And, in key Petrofac projects, like the Rabab Harweel Integrated Project in Oman, and the Upper Upper Zakum field development located offshore Abu Dhabi, it has been a key part of the delivery strategy.

But, at the Thaioil Clean Fuel Project, which involves a major expansion and upgrade to the existing Sriracha Refinery in Eastern Thailand, the technique has been taken to a whole new level. A large proportion of the entire facility is being modularised. In total, 380 units weighing-in at anything between 200 and 2,000 tonnes are being prefabricated at yards as far afield as India, China, and the Philippines – which, in terms of numbers, represents a two-fold increase on Upper Zakum and a six-fold increase on Rabab Harweel.

Vice President of Operations George Saad, who has overall responsibility for the project explains the rationale: “Petrofac has developed a matrix which helps us to decide whether to go with a traditional stick-built approach or to opt for modularisation. We weigh-up things like the contractual obligations, the timescales, the location of the site, the number of personnel able to work onsite, the availability of skilled labour locally, the logistics of bringing over-sized items onsite, and so on. And we come to the most logical decision. In the case of Sriracha, it was actually a contractual obligation but, in truth, given the nature of the site, it would have been impossible to do it any other way.”

The fact is, there is no spare space at all. The site, which is home to a live production plant, is hemmed-in on one side by a sacred mountain and on the other surrounded by the community of Sriracha. So, there are no laydown areas, no warehousing, and precious little room to do much stick-built construction. To compound the situation, the client, Thaioil, has placed a cap on the number of onsite personnel at 18,000 people – whereas, on a project of this scale, during peak periods you may expect to see around 20,000 to 30,000 workers.

So, from the outset, it was understood that modularisation would be the way to go. Petrofac opted to have most of its prefabrication handled at the Larsen & Toubro manufacturing complex in Hazira, India, where around 90 pipe racks, pipe bridges, and pre-assembled units are being built. Meanwhile, the consortium partners Samsung Engineering and Saipem are turning to a variety of facilities in India, the Philippines and Thailand.

An early challenge for the project team was to clear a path for the arrival of the modules, so they could be moved, from their sea voyage, onto the site and into position. To this end, a nearby marine offloading facility (MOF) was upgraded, the road from there to the refinery site was widened, and an entire network of roads within the facility was strengthened. As part of the planning process, the journey of each item was painstakingly mapped-out to ensure sufficient clearances for the module itself and the vast self-propelling modular transporters (SPMTs) which would carry them to their destination. Similarly, a selection of cranes was acquired to hoist each module into position, including a 3,000 tonne ringer crane – one of just two in the world.

Perhaps the biggest challenge of all, however, is the sequencing.

“Each of these 380 modules needs to arrive onsite in a precise order,” explains Michael Habr, Construction Support. “If a module gets here too late, it holds up the entire project. If it gets here too early, there’s nowhere to store it. To get everything right, we need to stay on top of the fabrication schedule, along with the sequencing of the construction, then factor in the journey time, and everything that may influence it – like the availability of ships and barges, the typhoon season, the high sea, the low sea, and so on.

A major milestone was reached in May 2021 with the safe arrival of one of the refinery’s distillation columns. “Although it arrived early on the construction process, this is one of the widest and heaviest items in the entire project,” explains Michael. “Yet we managed the offloading and the transportation smoothly and flawlessly. We knew that, if this unit could pass, every other would be able to pass. So, this was a big achievement – and also something of a relief.”

By mid-2021, despite the disruption caused by the Covid-19 pandemic, the engineering and procurement phases were substantially complete, as was the on-the-ground construction, and close to 60 modules had arrived safely for installation.

For Michael, who has been with the project from the outset, it’s an exciting time. “It’s great to see our plans coming to life. The preparatory work is complete, we have weathered some difficult challenges and, from here on in, it should be like a giant puzzle coming together, with all the pieces arriving at the right time, in the right sequence.”  

In the Engineering, Procurement and Construction business, modularisation is often described as being like piecing together a giant Lego set. In the case of the Sriracha Refinery project, the term just doesn’t do justice to the level of precision required – you could say it’s more like assembling a Swiss watch.

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