Thickness Measurement at the Port of Dundee on the Firth of Tay

Inspection services for ships at Dundee

Each service has its own page with the method, the class requirements and what the report contains.

Quays and work areas for gauging in Dundee

Rigs and large vessels lie at the heavy-duty quays at the eastern end of the port, where cranes, laydown areas and services are available and where the contractor carrying out the main repair works controls access. On a jack-up, we gauge hull plating and internal structure, preload and ballast tanks once they are emptied and ventilated, and accessible leg and jack-house structure, and use magnetic particle testing at welds that carry high cyclic loads. The work is planned with the rig owner's representative and the main contractor so that tank entries and lifting operations do not clash.

Cargo ships use the general berths along the river frontage, where gauging during discharge works in the usual way, hold by hold. For a full docking, ships and offshore vessels from Dundee usually move on to Rosyth or to a northern European yard, which makes a long Dundee stay a good time for the pre-docking readings that set out the steel list for the yard before the vessel leaves the Tay.

• Heavy-lift quay at the eastern end — rig hull, preload tank and leg structure gauging during repair or refurbishment.
• Prince Charles Wharf and adjoining berths — deck and grillage checks on heavy-lift vessels and barges after decommissioning lifts.
• General cargo berths on the river frontage — hold and tank gauging on coasters and bulk carriers during discharge.
• Lay-up and stacking periods — full condition surveys on rigs and offshore vessels idle between contracts.
• Wind project berths — deck, crane foundation and tank gauging between installation or maintenance campaigns.

Port state control, rig surveys and decommissioning rules

Ships calling at Dundee are subject to port state control by the Maritime and Coastguard Agency under the Paris MoU, applied through UK law since the UK left the EU. Jack-up rigs follow a different regime: as mobile offshore drilling units they are surveyed under their class society's rules for offshore units and the MODU Code, with periodic surveys that include thickness measurement of hull and preload tank structure, and a rig coming into the Tay for refurbishment is often doing so ahead of one. When it returns to work on the UK Continental Shelf, the operator's own assurance processes and the Health and Safety Executive's offshore regime add further scrutiny of structural condition.

Decommissioning brings its own rules. Structures removed from the North Sea are dismantled and recycled onshore under waste and environmental permits, and the heavy-lift vessels and barges that bring them in carry concentrated loads on sea-fastenings and grillages, which is why owners often want deck condition checked afterwards. On the ship side, the UK has its own ship recycling regulations in place of the EU regulation, though vessels trading to EU ports still keep an Inventory of Hazardous Materials. Owners moving older offshore vessels or rigs towards recycling can use a Dundee stay to establish structural condition before a sale or a final voyage.

Ships trading to Dundee are inside a sulphur emission control area, where fuel must not exceed 0.10% sulphur unless an exhaust gas cleaning system (scrubber) is fitted. Scrubber wash-water piping, the overboard discharge and the hull penetration around it are among the fastest-corroding parts of a modern ship, so they belong in the gauging scope at every docking and, on open-loop systems, between dockings.

How a thickness measurement job runs at Dundee

The sequence for a thickness measurement job at Dundee is short and written down, so the yard, the surveyor and the superintendent know who arranges what.

Dundee's small airport has limited scheduled services, so the team usually flies into Edinburgh or Aberdeen and continues by road or rail; Dundee sits on the railway between those two cities. Travel from India needs UK visitor visas, which we apply for once the job is likely, and rig owners planning refurbishment periods can give us enough notice to have them in place early. Access to the port is through ISPS-controlled gates, with passes arranged by the ship's agent or, for rigs, by the main contractor running the site.

• Send the vessel name or IMO number, ship type, class society, the survey due (annual, intermediate, renewal survey number, CAP or owner's condition survey), the port and dates, and the scope you expect.
• We confirm the scope against the class rules for that survey, prepare the thickness measurement plan with frame and section references, and say whether the measurement will be credited to a class survey.
• Mobilisation is planned around visa lead times and the vessel's schedule; the ship's agent arranges port access, and the yard or ship arranges staging, lighting, ventilation and gas-free certificates.
• Gauging with calibrated ultrasonic thickness gauges: through sound coatings only where the gauge's through-coating mode has been verified on a coated reference, otherwise on cleaned bare steel, with every reading tied to its frame, strake and location on the sketch.
• Readings are compared with original thicknesses as work proceeds; substantial and excessive corrosion and any cracks are reported to the attending surveyor and the superintendent the same day.
• The final report is issued on the class thickness-measurement formats with sketches, a summary of locations exceeding the allowable margins, piping tables where piping was in scope, and the gauge calibration and technician certificates.

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