Ultrasonic Thickness Gauging for Ro-Pax and Ice-Class Ships in Stockholm

Inspection services for ships at Stockholm

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

Where gauging happens in the Stockholm port system

The city ferry terminals at Värtahamnen and Stadsgården are workable for short scopes during turnarounds, but space and time are limited and access passes through the ferry operators' security arrangements. Kapellskär and Norvik offer more room and longer stays for freight ships, and tankers at Nynäshamn lie alongside for the length of discharge, giving time for ballast-tank and deck work if the terminal and master agree. Short ferry scopes can also be split across several turnarounds, measuring a few spaces on each call until the planned list is complete.

Stockholm is not a docking port for large ships, and Swedish and Finnish ferry operators typically dock their ships at yards in Finland, Poland, Estonia, Lithuania, Germany or Denmark. For a ferry, the most effective approach is usually pre-docking gauging in Stockholm on the spaces that can be reached in port, followed by the bulk of the measurement at the yard. Winter work on open decks and at the waterline is affected by short daylight and freezing temperatures, which complicate couplant and surface preparation, so external measurements are better scheduled outside the coldest months where the docking plan allows.

• Värtahamnen ferry terminal — machinery-space piping and accessible vehicle-deck measurements on cruise-ferries during their turnarounds.
• Stadsgården ferry berths — piping and deck gauging on ferries during their daytime stay, planned with the chief engineer.
• Kapellskär — gauging on ro-pax and freight ships serving Åland and Finland, where stays allow ballast tank and deck work.
• Stockholm Norvik Port, Nynäshamn — ballast tank and deck gauging on container and ro-ro ships within the berth window.
• Nynäshamn refinery berths — ballast tank, void-space and deck measurement on tankers during discharge, subject to terminal approval.
• Docking yards around the Baltic — ice-belt, shell and tank gauging on Stockholm ferries at their annual or renewal survey docking.

Ice class, ECA and regulation for ships trading to Stockholm

Sweden is a Paris MoU member and an EU state, applying the EU ETS to shipping from 2024 and FuelEU Maritime from 2025, regimes that bear directly on large ro-pax ferries with high fuel consumption and fixed schedules. Stockholm lies inside the Baltic Sea SOx ECA at 0.10% sulphur, and the ferry fleet here has been an early adopter of LNG fuel, battery-hybrid systems and shore power, all of which add foundations, penetrations and piping that need a structural baseline when retrofitted.

Winter navigation in the northern Baltic is governed by the Finnish-Swedish ice class rules, and the Swedish and Finnish maritime administrations set traffic restrictions that require minimum ice classes for ports in the Gulf of Bothnia and, in severe winters, further south. Owners keep ice class for commercial reasons, and maintaining it means keeping ice-belt plating and frames within the allowances of the ice-strengthening rules. Ice damage such as indents, buckled frames and cracked welds at the bow is typically recorded after a hard winter and repaired at the next docking. Thickness measurement and crack detection on the ice belt and bow structure before the yard stay lets the owner scope those repairs accurately.

Ships trading to Stockholm 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 Stockholm

Most of the work on a Stockholm job happens before the team boards: scope, plan and access are settled first, so the time on board goes on measurement.

Stockholm Arlanda Airport is the international gateway, connected to the city by rail; Nynäshamn and Kapellskär are reached by road or rail from central Stockholm. Ferry, freight and refinery terminals are all ISPS-controlled, and the ship's agent or the ferry operator arranges access for named technicians. Sweden is a Schengen state, so the team travels from India on Schengen visas, which also cover onward travel to docking yards in Finland, Poland or the Baltic states. Planned dockings should be notified as early as possible, and winter schedules are planned with daylight and temperature in mind.

• 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.

Related