Stack Reinforcement
The purpose of the equipment is to reinforce the sub-sea annular cavity in a flare stack.
To perform this activity the following equipment is provided per flare stack leg:
- ROV equipment shelf, one-off
- Flare stack clamps complete with ROV docking station, seal and isolation valve, four-off
- ROV operated sub-sea drill, one-off ROV grouting probe, one-off
The ROV is initially installed with the lightweight equipment shelf on which is located flare stack clamp number-1 and the preinstalled sub-sea drill connected into the ROVs hydraulic supply.
The ROV latches the clamp onto the pile towards the top of the flare stack and drills a 2" NS hole in the stack. The ROV then undocks leaving the clamp-1 mechanically held in position on the stack.
Towards the base of the flare stack the ROV positions clamps 2, 3 & 4 and also drills three more holes. This completes the sub-sea drilling operation with four clamps positioned on the flare stack.
At this point the grouting probe replaces the drill. The ROV re-docks onto the base clamp (clamp-4) and grout is injected from the topside into the annular cavity until grout is pumped from the clamp above (clamp-3). The ROV close the isolation valve on the clamp-4 and un-docks. The ROV re-docks onto the clamp-3 and closes the isolation valve. The ROV again undocks and the system is now left to allow the grout to set.
Once the grout has set and there is now a hardened slug of grout in the annular cavity, the ROV docks onto clamp-2. Grout is again pumped from the topside and the full cavity is filled until grout is evident at clamp-1. The ROV un-docks and closes the isolation valve on clamp-3. The ROV redocks onto clamp-1 and closes the isolation valve.
The operation is now complete and once the grout has fully set the clamps can be removed by the ROV.
This equipment has been successfully used to repair three flare stack legs on July 10 of the coast of Egypt. All equipment is commissioned offshore by Tekmars service engineers prior to installation.
Client benefits provided by solution:
- Long term reinforcement of severely corroded flare stacks ROV remote installation.
