Thickness Measurement for Gas Carriers and Tankers Loading at Kårstø

Inspection services for ships at Kårstø

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

What can be measured alongside the Kårstø quay and at anchor

Gas carriers at Kårstø are gauged under a combined permit regime: the ship's own enclosed-space and work-permit procedures, and the terminal's rules on hazardous areas, ignition sources and people on the quay. Ultrasonic gauges and portable lamps are electronic equipment, so inside the gas-dangerous zones on deck they are allowed only if certified for the zone or if the area has been declared safe, which in practice keeps measurement on the cargo deck to a minimum during loading. Ballast tanks, the double bottom where it is reached through ballast spaces, the engine room, the steering gear flat and the accommodation block are the usual working areas, once each space has been ventilated and certified.

Hold spaces around independent cargo tanks are generally kept inerted or under dry air in service and cannot be entered during a terminal call, so hold-side structure and tank supports wait for a docking. Kårstø is a gas plant, not a repair site; gas carriers and tankers dock at specialised yards in northern Europe or further afield, and the regional yards at Ølensvåg and Stord mainly work on offshore vessels, rigs and platform modules. Readings taken at Kårstø therefore usually serve as a pre-docking estimate or as the owner's condition monitoring between surveys.

• Kårstø loading berths, gas carriers — ballast tank, engine-room and steering-gear piping and accommodation-area gauging during loading, within permitted zones.
• Kårstø loading berths, tankers — ballast tank and deck gauging on ESP tankers lifting naphtha or condensate, cargo tanks kept closed.
• Boknafjord anchorage — short scopes by launch on ships waiting for a loading slot, where the master and agent agree.
• Docking yards chosen by the owner — hold spaces, tank supports, cargo-tank welds and bottom plating, after pre-docking readings at Kårstø.
• Repeat calls on regional ethane runs — staged ballast tank programmes spread across several loadings.

Survey regimes and terminal safety behind Kårstø gauging

Ships loading at Kårstø come under Paris MoU port state control, carried out by the Norwegian Maritime Authority, whose headquarters are in nearby Haugesund. Gas carriers are built and surveyed to the IGC Code and the class rules for liquefied gas carriers: hull thickness measurement follows the class survey cycle, while the cargo containment system, its secondary barrier and the hold spaces have their own examination requirements tied to the tank type. Fully refrigerated LPG carriers with prismatic tanks use the inner hull as part of the secondary barrier, which makes the condition of hold-side plating and stiffeners a cargo-safety matter as well as a structural one.

Naphtha and condensate tankers are oil tankers in regulatory terms, so the ESP Code's enhanced surveys apply, with gauging and close-up survey of cargo and ballast tanks increasing at each renewal survey. The oil and gas companies lifting cargo at Kårstø vet the ships they charter, and recent condition data strengthens the owner's position when a ship is nominated. For older gas carriers and tankers in this trade, the Inventory of Hazardous Materials expected of ships calling at EU ports adds a further consideration: whether a ship is worth renewing steel on, or is better sold, depends on knowing its true condition.

Ships trading to Kårstø 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 Kårstø

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

Haugesund Airport on Karmøy and Stavanger Airport at Sola are both within reach by road, Stavanger offering the wider choice of international connections. Kårstø is a high-security industrial site: besides ISPS access through the ship's agent, the terminal requires advance registration, a safety induction and approval of any equipment taken aboard, so the team's details go in well ahead of the loading date. The technicians travel from India on Schengen visas, and because loading slots can move at short notice, keeping the team's travel plans flexible is sensible.

• 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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