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to 18in. above the top of the lower pipeline. An ROV will then take a 1.2m-high crossover formwork off the deployment sled and maneuver it into position.

Pipelines

Ordinary Portland cement (OPC) grout is mixed on deck. It is pumped to the grout bag via a deepwater grout umbilical, connected to the formwork deployment sled. After suffcient grout has entered the formwork to stabilize the bag, checks are made to ensure that the bag orientation and position is still correct and that it is flling evenly.

The crossover grout bag is

Portland cement grout designed to be flled in three stages is mixed on deck and due to its size and volume. The pumped to grout bags lower compartment is flled and at the seabed.

allowed to cure suffciently to sup- port additional grout in the upper compartments. for greater design and fabrication the two steel half-shells of the tolerances, as the grout flls the clamp to the seabed and maneu-

Grouted clamps annulus and evenly distributes the vered them into position around the

Another form of remedial work load of the object the clamp is being pipeline, and tightened the bolts. is the grouted clamp. These have placed around. Crews delivered grout using a deep- been used successfully to restore In 2007, the 233 mile, 36in. CATS water grouting umbilical system.

pipelines, strengthen jacket mem- pipeline supplied 12% of the UK’s Due to the extra load on the bers, and repair caissons. A clamp gas. However, the pipeline had to be pipeline, a fabric formwork was is composed of two or more steel shut down due to damage from a ves- installed under the clamp to pro- segments, which are placed around sel’s dragged anchor. A fast response vide additional support and prevent an object. The segments are bolted and frst time fx was vital to get buckling. In total, 28 tonnes of together along their edges prior to supplies back up and running. A cement was used: four tonnes for the the injection of grout into the annu- repair sleeve was bolted into position clamp and 24 tonnes for the fabric lus between the clamp and the asset. and the grout hose was connected formwork.

The grouted repair clamp allows to the inlet. Grout was pumped into Inspection, repair, and mainte- the annulus. Accurate and complete nance projects demand an experi-

Clamp segments are bolted around an flling was controlled using carefully enced supply chain whose skills can object, and then the annulus is injected positioned overfow ports and valves. be deployed at a moment’s notice. with grout to create a permanent seal.

The repair was completed ahead of Tried and tested offshore proce- schedule and at short notice, with dures, coupled with planned-for the client acknowledging the com- contingencies, and astute offshore pany’s effciency. personnel, ensure savings in both

This same technique was used project costs and time. more recently in deeper water.

James Bell has been

Saipem America awarded a contract managing director of to repair a damaged pipeline in

FoundOcean since 2005. the Gulf of Mexico. A cable-laying

He has been involved vessel’s anchor had dragged along with numerous chal- the seabed and over the 750m-deep lenging projects includ- pipeline in bad weather. This ing the BP CATS pipeline repair, resulted in the pipeline being oper-

ConocoPhillips Ekofsk strengthening, ated at a reduced pressure until

Exxon Diana Truss Spar riser system. remedial work was complete.

Bell earned a Civil Engineering degree

To enable access, the seabed was from London’s City University.

dredged around the damaged pipe- line section. An ROV transported

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