Ultrasonic Thickness Measurement for Tankers, LPG Carriers and Supply Vessels at Mongstad

Inspection services for ships at Mongstad

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

Where a ship can be gauged at Mongstad

Everything at Mongstad is organised around cargo safety. The crude jetties, refinery product berths and LPG loading berths lie inside the terminal's restricted area, where hot work is forbidden, electrical equipment taken on deck has to satisfy the hazardous-area rules of both ship and terminal, and enclosed-space entry needs the ship's permit together with the terminal's consent. Surface preparation is done by hand, because power tools that might spark are not welcome near cargo. In practice, ultrasonic gauging on a tanker alongside concentrates on segregated ballast tanks, the peak tanks, the engine room and deck plating away from manifolds and vents.

The supply base is a different working environment. Platform supply vessels lie at quays served by cranes, outside the tanker safety zones, and where the vessel has arranged tank cleaning, bulk and liquid tanks can be entered once they are certified safe. Offshore vessels in port between charters are the most practical gauging jobs at Mongstad. For dry-docking, tankers trading here go to yards chosen by their owners, often far from Norway, and supply vessels to the repair yards along the west coast; readings taken at Mongstad then feed the steel estimate for that docking.

• Crude terminal jetties — segregated ballast tanks, peak tanks and deck plating outside the cargo area on crude and shuttle tankers, inside the terminal's permit system.
• Refinery product berths — ballast tank and forepeak gauging on product tankers loading clean or black products.
• Berths loading Vestprosess propane and butane — deck and double-bottom readings on LPG carriers, with the cargo tanks left for dry dock.
• Mongstad supply base quays — tank, chain-locker and deck gauging on platform supply vessels between runs or between charters.
• Repair yards on the west coast — full renewal-survey gauging on supply vessels whose docking follows a period of work from Mongstad.

Vetting, port state control and the oil-company rules behind a Mongstad call

Port state control in Norway is carried out by the Norwegian Maritime Authority under the Paris MoU, and Mongstad's traffic falls squarely into the ship types that draw the closest attention: oil tankers, gas carriers and chemical tankers. Under the Paris MoU regime, those types become candidates for an expanded inspection once they are more than twelve years old, and an inspector looking at an older tanker may examine its structural condition, ballast spaces included, and ask for its thickness measurement and repair records. A tanker whose latest gauging shows wastage close to the allowable diminution, with no plan for renewal, invites questions.

Commercial vetting carries as much weight as regulation. Tankers chartered to lift crude and products at Mongstad are screened by the charterer and the terminal, and the SIRE 2.0 inspection regime that OCIMF rolled out in 2024 puts more emphasis on what the inspector actually sees on board, which makes coating breakdown and wastage in ballast spaces harder to explain away. Many charterers also expect older tankers to hold a Condition Assessment Programme rating, and that rating rests on thickness data. Supply vessels serving the Norwegian shelf answer to the oil companies' contract standards as well as to class, so an owner tendering for a long charter is better placed with a recent, documented set of readings.

Ships trading to Mongstad 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 Mongstad

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

Bergen Airport, Flesland, is the arrival point, and Mongstad is reached from there by road north through the Bergen area. The crude terminal and the supply base are ISPS facilities with their own induction and security checks, so the ship's agent sends the team's names, passport details and equipment list in advance and confirms the boarding time with the terminal. Norway belongs to the Schengen area, and our technicians travel from India on Schengen visas; a vessel that calls at Mongstad regularly is easiest to serve when the visas are arranged before a specific loading is fixed.

• 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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