|
Marine construction of seawater intake pipelines of Abutaraba Desalination Plant was undertaken by subcontractor contract with TML. For laying 2 HDPE seawater intake pipes with lengths of 639 m and 629 m and 1400 mm diameter and 2 HDPE chlorination pipes with 640 m length and 100 mm diameter on the seabed, installation of concrete weight rings (anchors/blocks) and fastenings, and connecting these pipes to Abutaraba Desalination Plant, following operations were carried out:
§ .Concrete weight rings were installed by a crane onto the HDPE intake pipes floating over the sea surface in Port of Benghazi and then, the pipes were tugged to the project site in Abutaraba, 100 km away.
§ .At the project site in Abutaraba, our divers realized an extensive survey in order to be able to plan required operations before laying the pipes.
§ .Offshore and onshore trenches were prepared proper for the pipelines. In this regard, predetermined route on the seabed was excavated, dredged, graded, and leveled by using floating crane Herkül, underwater stone crusher, hydraulic polyp grab, and rock drillers. On the sea bottom, rocky parts were broken and holes were filled. Especially, rocky seabed under the offshore intake heads was leveled appropriately.
§ .Onshore part of the HDPE intake pipes were laid into the trench dug onshore by using land crane, excavator, and GPS Total Station.
§ .The other part of the HDPE intake pipes and 2 intake heads were submerged into the sea and laid into the trench at predetermined coordinates by floating crane Herkül and tug Pegasus-3.
§ .Alignment and connection of the intake pipes with the offshore intake heads and the basin onshore was realized.
§ Additional concrete weight anchors were fixed on the submerged pipes.
§ .2 HDPE chlorination pipes were submerged, laid into the trench, fixed on the seabed from the basin points to the intake heads, and connected to the inlets of the injection systems within the basin and to the inlets of the spray systems within the intake heads.
§ .Sacrificial anodes were installed on metallic parts of the equipment for cathodic protection against corrosion.
§ .During the pipe laying and in its final position, stress and tightness analyses were done. Underwater flange connections were tightened by our divers using Torque meter.
§ .For cleaning, maintenance, and repair works of the pipeline system, pig launcher system connecting the basin and the HDPE pipelines were installed, fitted, and aligned on shore.
§ .Marker buoys were installed by using GPS at predetermined coordinates for establishing offshore warning system.
§ .After the intake pipes, chlorination pipes, and intake heads were laid and the trench was backfilled, our divers realized inspection divings for controlling the pipeline. Fixation of the pipes and intake heads was accomplished by leveling the rises by using water jets and underwater rock drillers and the spaces under them by placing fabric formwork bags. Fabric formwork bags were also used for scour protection by placing fabric formwork bags around the pipes and intake heads along the route of whole pipeline.
Floating crane Herkül, tug Pegasus-3 and tug Vega 3, and workboats were used in the operations.
|