Offshore Archives - DUC Marine Group

Installation of a boatlanding

ducmarinegroup — Thu, 04 Mar 2021 11:35:03 +0000

INSTALLATION BOATLANDING

30 km North of Helgoland, Germany.

Because the distance of the fenders of several CTVs to the existing current sports of the boatlanding was not sufficient, the Client asked DUC Marine Group to install two extension pieces. For this job DUC mobilised a big Multicat, a CTV, a RIB and a Rope Access Team. The ladders were loaded in the port of Delfzijl (Holland) and were prepared on deck for installation.

Because of the lifting height and the movement of the vessel on the swell, DUC was careful not to damage the steel structures and decided to hoist the pipes with an electric hoist and a Rope Access Team. Due to the existing inter array and export cables anchoring was prohibited. Mooring with ropes to the jacket was also prohibited.

To overcome this problem the extension pieces were gently lowered into the water with the Multicats Deckcrane and connected to a 5 ton lifting bag underwater. The lifting bag was then towed to the boat landing and hoisted into position. All bolts were tightened to the correct torque. In total 4 pieces were installed.

Categories: Boat landing, Maintenance and Repairs, Offshore, Offshore Construction and Installation, Oil and Gas, Renewables, Wind Park, Rope Access

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Salvage of lost suspension bridge parts

ducmarinegroup — Thu, 04 Mar 2021 11:21:33 +0000

SALVAGE OF LOST SUSPENSION BRIDGE PARTS

IJmuiden Approach Channel, Netherlands

The outbound vessel “Wilson Leer” lost her deck cargo of steel modules for a suspension bridge, during her way out of IJmuiden to Sweden.

Six elements of 20 m x 6,5 m x 1,5, weighing 31 tonnes in air, were lost.

A crane vessel, a fully equipped diving team and materials including a decompression tank and a Nitrox unit were mobilised.

It took only four days to complete the work and clear the channel of the debris.

Categories: Salvage, Offshore, Offshore Salvage, Bridge

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Salvage of broken vibrocore pipe

ducmarinegroup — Wed, 09 Nov 2016 15:50:17 +0000

SALVAGE OF BROKEN VIBROCORE PIPE

Near the coast of Zeebrugge (B) and windfarm Rentel a broken vibrocore pipe had to be searched and salvaged.

With our vessel RAM, a team of divers and the use of an airlift we successfully managed to retrieve this pipe from the seabed.

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Replacing oil pipeline

ducmarinegroup — Thu, 14 Jan 2016 16:29:53 +0000

REPLACING OIL PIPELINE

In Ashkelon, DUC Marine Group helped with the replacement of two 1500-m sections of pipeline. These oil pipes ran from a refinery to the sea where they were connected to a SPM (Single Point Mooring) buoy.

DUC was assigned the task of using PLIDCO clamps to connect the two new sections of pipe to the oil pipelines.

The four clamps were installed at a depth of 33 metres. This meant that there was limited diving time and a team of 13 divers and two decompression chambers were required to be able to work through the day.

After installing the PLIDCO clamps, they had to be welded with an ‘A height’ of 10 mm (eight beads of weld to make one weld!)

This was done in the dry in a habitat. Two divers entered the habitat at the same time to achieve a certified weld.

The project was concluded successfully, on time and within budget.

Categories: Civil Underwater Construction, Inshore, Offshore construction, Oil and Gas, Pipelines

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Wall thickness measurements in Georgia

ducmarinegroup — Thu, 14 Jan 2016 15:54:49 +0000

WALL THICKNESS MEASUREMENTS IN GEORGIA

Georgia, Europe

At the end of 2011, DUC Marinegroup performed wall thickness measurements on a quay wall made of sheet piling with a cap. The quay wall was 360 metres long and measurements had to be taken at four places to a depth of 10 metres. Using a wall thickness meter, a diver took readings at the specified places.

Categories: Maintenance and Repair, Inshore, Non-Destructive Testing, Offshore, Preservation, Survey and Inspection

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Mauritanian iron ore jetty

ducmarinegroup — Thu, 14 Jan 2016 15:46:53 +0000

MAURITANIAN IRON ORE JETTY

Mauritania, Africa

During a five-year project, DUC Marinegroup performed maintenance to an iron ore jetty in Mauritania, Africa.

The jetty was protected by anodes that had to be checked. As anodes decay in the course of time, regular maintenance and repair is necessary.

DUC Marinegroup has its own equipment to carry this out, including C.P. meters and wall thickness meters for use under water. Anodes that did not function correctly were replaced or additional anodes were installed.

Categories: Maintenance and Repair, Inshore, Offshore, Cathodic Protection, Civil Underwater Construction, Non-Destructive Testing, Preservation

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Inspect, testing and replacing of anodes

ducmarinegroup — Thu, 14 Jan 2016 15:37:34 +0000

INSPECT, TEST AND IF REQUIRED REPLACE ANODES

Port of Rotterdam and Amsterdam, The Netherlands

In the Port of Rotterdam and Amsterdam, DUC Marine Group regularly checks anodes and replaces them if necessary. Not only in the Netherlands we inspect and replace anodes but all over the world. Regular exchanging of anodes are performed in United Kingdom, Africa and Europe.

Categories: Maintenance and Repairs, Inshore, Offshore, Non-Destructive Testing, Survey and Inspection, Cathodic Protection, Civil Underwater Construction

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Vopak pile encapsulation

ducmarinegroup — Thu, 14 Jan 2016 15:19:18 +0000

VOPAK PILE ENCAPSULATION

Port of Rotterdam, Nederland

At Vopak in the port of Rotterdam, DUC Marinegroup blasted and preserved steel piles in a five-year project by high-pressure water cleaning and installing polyester shells to then inject them with a 2-component epoxy resin so that the shell is glued to the pole. ” is going to be.

This gives the steel pole a kind of paint coating of approx. 1 cm thick. This will stop the pole from rusting on the wind water line.

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Wreck removal Eemsgeul

ducmarinegroup — Thu, 14 Jan 2016 14:53:56 +0000

WRECK REMOVAL EEMSGEUL

PHASE 1

Before dredging could start for a new deep navigation channel to the busy Port of Eemshaven, in the far North of the Netherlands, six wrecks had to be removed. DUC Marinegroup provided salvage dive assistance to the main contractor during the full execution period. All objects were inspected. Some parts were exposed using an airlift and then connected with slings. Other big objects were divided into smaller parts underwater using Broco-torch.

The performance of the Mass-Flow-Excavator was carefully monitored by DUC. Diving was performed from a vessel of the main contractor.

PHASE 2

In the second season of this job two remaining wrecks needed to be removed at a depth of up to 18 m :

– one wreck estimated 30 m x 20 m x 3 m at a minimum depth of 12 m and

– one of 50 m x 20 m x 4 m at a minimum depth of 14 m.

DUC Marinegroup was sub-contractor for this job and performed the works with two of their own vessels; m/v RAM and m/v REIGER. The sand above and around the wrecks was dredged with a big 10” airlift during tidal currents. During slack waters the divers connected hoisting slings and big parts were cut into smaller pieces. In only 12 weeks the two wrecks were completely removed and the bottom was cleaned. The debris was transported to approved recycling companies.

Category: Salvage, Offshore Salvage, Inshore Salvage

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Clearance sea-floor of several anchorages

ducmarinegroup — Thu, 14 Jan 2016 14:40:34 +0000

CLEARANCE SEA-FLOOR OF SEVERAL ANCHORAGES

The Dutch Ministry of Infrastructure and the Environment awarded DUC Diving a contract for cleaning the designated anchorages in front of the seaports of Flushing, Rotterdam and IJmuiden. Vessels sometimes lose their anchors due to metal fatigue or bad weather. The lost anchors are a danger to the vessels who use the anchorage, as they may cause their own anchor to get stuck during retrieval.

In two months, DUC Diving cleared the sea bottom around the anchorages. Not only did we remove all objects but also their position, orientation and state were described in detail. For this operation we deployed our vessel Ram and a team of 8 persons. The Ram positioned herself on a three point mooring above the location, and a diver descended to the seafloor.

Due to the dynamics of the sea, often the target was washed over with a layer of up to 1 m of sand, so the divers had to search for the object. After locating the object and a documenting a thorough description on how the object was found, the object was hoisted onto the deck, cleaned and inspected again.
In total approximately 300 m2 kilometer was searched and 300 ton of steel debris was salvaged, including
– 40 anchors (individual anchors 700 to 8.000 kg);
– 3.000 meter chains (individual shackles 10 cm to 50 cm);
– 500 m steel cable;
– Fish netting, boulders, concrete and a 17th century canon.

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