Gibdock completes repairs to powerful dredge

DECEMBER 11, 2012 — Gibraltar ship repair yard Gibdock has completed its first project for Belgian dredging contractor DEME— alongside maintenance and repairs to the rock cutter suction dredge Ambiorix.

Delivered by IHC Dredgers in May 2012, the 124 m long, 28,200 kW Ambiorix is among the most powerful vessels of its type in the dredging industry.

Ambiorix can dredge to a water depth of 35 m and is designed for work in heavy soil and hard rock. It is equipped with two inboard dredge pumps and one submerged dredge pump on the cutter ladder. It also has a system to load barges moored alongside.

Following an assignment undertaken in Morocco, Ambionix underwent a 12-day overhaul berthed alongside Gibdock’s South Mole. The shipyard was tasked with fabricating additional dredging equipment and carrying out wear and tear-related repairs to the cutter heads and cutter ladder front. The yard’s strategic location in the western Mediterranean made it an ideal location to carry out the work before its next scheduled assignment.

To complete the project in the shortest possible time, Gibdock made staff available around the clock. The most challenging part of the job was the repair to the four cutter heads and the cutter ladder front wearing plates, the latter requiring a rigorous welding procedure to upgrade worn wearing plate areas. The job demanded high levels of skill from Gibdock’s welding team to meet the exacting specifications from DEME.

Frederik Mertens, Technical Superintendent, DEME Maintenance & Repairs Department, said: “It is always difficult to get the right hands on these specialist jobs for our highly sophisticated equipment. Thanks to good work preparation, an on-site visit prior to the arrival of the vessel at the shipyard, the skilled workers and a good collaboration between shipyard, owners and owners’ welding supervisors, these jobs could be finished in a safe way and within the scheduled time frame.”

Gibdock Ship Repair Manager, Jonathan Pocock, said: “Our most experienced welding teams were deployed in shifts to ensure 24 hours a day work patterns so that the temperature of the cutter heads could be kept between 120deg C and 150deg C. Cold surface welding had to be avoided for the cutter heads, while it was of the utmost importance not to bring too much heat into the wearing plates, which would lead to cracks and deterioration of the wear resistant Tungsten Carbide welding beads. The welding specifications and procedures had to be followed meticulously.”

Each of the cutter heads on the Ambiorix weighed in at 27 tonnes. Their transport from the vessel to Gibdock’s workshop, and handling them in a safe and timely manner also required strict pre-planning.

Gibdock Commercial Director, Richard Beards, said: “Ensuring that repairs to Ambiorix were delivered in timely fashion required flexibility in our work scheduling, as well as high skill levels and close observance of our quality assured safety practices. We see dredger projects as key references as we continue to pursue complex work where redelivery on time and quality of work are key factors.”