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J-Tube Sealing

Wheatstone J-Tube POP

Subcon has successfully applied multiple J-Tube gel plugs to seal the interface between risers/umbilicals and the J-Tube. J-Tube seals consist of a bottom plug in the J-tube near the bellmouth and a grouted annulus above it.

The bottom plug can be a proprietary fabric formwork or a sealing gel plug. After the bottom plug has cured and sealing is confirmed, the remaining volume of the J-Tube is filled with the gel product.

FAQ’s

During umbilical pull-in, the umbilical can be damaged by abrasion against the J-Tube. This abrasion can put the umbilical at risk of corrosion and reduce the design life significantly.

The gel seal can include corrosion inhibitors to ensure the expected design life is met.

The gel material has a heavier density than seawater so will displace the seawater to the top of the J-Tube as the gel is pumped into the annulus.

A stinger is lower to the base of the J-Tube annulus to ensure the gel is not free falling through the water column.

In addition to this, an anti washout agent is a constituent of the mix design to further ensure that the gel does not lose its integrity.

The gel is a thixotropic fluid that is fluidised when it undergoes shearing action (ie the mixing process) and becomes steadily more viscous as it stops moving.

This means it can provide a permanent seal, but can be refluidised by water jetting during the decommissioning process.

Wheatstone J-Tube POP

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