Retractable Flare Maintenance – Malaysia LNG

The plant 

The MLNG plant is located in the eastern part of Malaysia near the town of Bintulu. 

On the plant, a retractable flare stack built by Johnn Zink is in operation. It has two flare risers with a flare tip on each. The high-pressure flares, A6331A/B, showed signs of buckling at the 45 degrees miter joints and flare tips. Replacing the components was proposed. 

MLNG awarded Trisystems the contract to replace the flare tips and the miters of the retractable flares. Trisystems then requested Conbit for assistance. The project scope included replacing both flare tips and replacing (cutting, bevelling, and welding) a new miter section of the riser pipe.

Conbit crew

The team consisted of eight members, including a team leader, welder, onsite machinists, and rope access technicians. Conbit worked together with its Malaysian partner, Trisystems, and its Thai partner, CR Asia, for this project. The team worked on the project for 45 consecutive days.

The execution 

The team used the retractable flare system of the derrick. This system is based on removing the bottom section of the riser one by one. It means that the bottom riser section is first unbolted from the corresponding riser sections. This is tilted until it is in the horizontal position, then it will be lowered again. This process is continued until the last riser with the flare tip is horizontal on ground level. All sections were then lifted and moved away from the flare stack for maintenance work.

At the maintenance area, the team unbolted the first flare tip. They cut the miter joint of the flare riser and then welded the new milter joint. A new flare tip was then bolted onto the new welded miter. The team then installed it in the flare derrick in the reverse procedure.

Retractable flare 

In a retractable flare, one flare stack can be lowered while the others remain in operation. This enables maintenance activities to be performed at ground level without decreasing the flare capacity too drastically. Because of the weight and size of such retractable flare risers, an experienced crew is essential to perform this lifting service.
Besides that, local circumstances and the flare condition can require adjustments throughout the project. Conbit has experienced many unforeseen circumstances in its projects and therefore can adapt to changing situations.

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Together with CR Asia, the project was executed safely and on time. 

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