HT Energy has been awarded the FSO riser testing scope covering onshore pigging and flooding, offshore leak test, dewatering, and N₂ packing for the 4-inch and 8-inch flexible risers. The project has entered the onshore phase.
The scope starts at the yard with pigging and flooding on both riser sizes, run as separate trains given the difference in bore tolerance and end fitting clearance between the 4-inch and 8-inch lines. Pig selection and running speed for flexible risers do not follow the same rules as rigid pipe. Bend stiffener and end fitting geometry constrain pig OD and hardness far more tightly, and a stuck pig inside a flexible carries a different cost profile than a rigid spool. Flooding fills the bore fully with treated water, removing air pockets that would otherwise skew the hydrostatic test result offshore.
Once onshore pigging and flooding clear acceptance, the risers move to the offshore phase for hydrostatic leak test against the design pressure, followed by dewatering and N₂ packing to bring each riser to lay-up condition ahead of connection to the FSO. Dewatering on flexible risers needs a controlled pigging or displacement approach rather than straight blowdown, because trapped water pockets in the annulus or at bend restrictors do not clear the same way they would in rigid pipe. N₂ packing then holds the bore at a stable dry, inert lay-up pressure, protecting against internal corrosion during the window before hookup and preventing any moisture ingress that would compromise the pipe’s carcass or pressure armor layers.
Bore condition and bend restrictor integrity get checked at every stage transition, onshore and offshore, not just at final handover. On flexible riser work that discipline matters more than on rigid pipe. Damage to the internal layers is not always visible from outside, and a defect missed at the onshore stage becomes a much harder and more expensive problem to catch once the riser is offshore and connected.
HT Energy’s crew is mobilized onshore now, running the pigging and flooding program on both riser sizes in parallel. Full award scope and technical package available on request.
