Tie-in sequence

Follow the seven-stage process which is used to join two segments of pipe together

1. Survey

Prior to any human divers arriving at the installation site, a survey is conducted by ROVS to determine everything is in place.

2. Cutting

When in position, the pipe segments may overlap. If so, a diamond wire cutter is used to slice the high-tensile steel.

3. Plugs

Welding plugs are inserted into each end of the segments to hold back the water from the welding area of the habitat.

4. Bevelling

A bevelling machine gives both pipe ends a smooth finish. Their surfaces are measured to ensure they are uniform.

5. Lift

Three pipe-handling frames are used to lift and shift the pipe segments into position – vertically or horizontally.

6. Weld

The segments are then welded together in the welding habitat. Post-weld, the join is inspected using ultrasonic tests.

7. Retraction

Once the welded area has been signed off, the welding habitat is removed, shortly followed by the PHFS.