Ship Thickness Measurement and Hull Gauging in Shanghai

Inspection services for ships at Shanghai

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

Where hull gauging in Shanghai takes place

Most ultrasonic thickness gauging in Shanghai falls into three settings. At the container terminals the work is limited to what can be reached during cargo operations, so it suits weather deck structure, hatch coamings, accommodation and machinery-space piping, and scrubber overboard lines. At anchorage in the estuary, a bulk carrier or tanker in ballast can open tanks and holds, and the team works from a launch arranged by the ship's agent. At a repair yard the whole ship is available, staging and lighting are in place, and gauging can run alongside the class surveyor's close-up survey.

Shanghai's own big shipyards — Jiangnan on Changxing Island, Hudong-Zhonghua and Shanghai Waigaoqiao Shipbuilding — concentrate on newbuilding, so ships trading to Shanghai often dock for repairs elsewhere, further up the Yangtze or in the Zhoushan archipelago to the south. We plan the mobilisation around wherever the ship is actually going to sit still, and keep the measurement plan consistent from pre-docking gauging to the final survey report. Where the next docking is elsewhere in China, the Shanghai readings are handed over with their locations marked on the ship's drawings, so the next yard and surveyor can use them directly.

• Yangshan Deep-Water Port — mainline container ships during their working time alongside; weather deck, hatch coamings and scrubber overboard lines, reached without disturbing the crane plan.
• Waigaoqiao container terminals — gauging on feeders and intra-Asia container ships, where ballast tanks can sometimes be opened during a longer stay.
• Yangtze estuary anchorages — bulk carriers, ore carriers and tankers waiting for berths or river passage; hold and tank gauging by launch through the ship's agent.
• Oil and petrochemical terminals around the estuary — product and chemical tankers alongside; deck, external shell and piping readings, with tank entry only once gas-free certification allows.
• Repair yards on the lower Yangtze — renewal survey gauging, pre-docking steel estimates and re-gauging of renewed plating during drydock periods.
• Wusongkou cruise terminal — piping and structural gauging on cruise ships during turnaround calls, scoped around passenger operations and the ship's own maintenance plan.

Port state control, emission rules and the Shanghai market

Shanghai falls under the Tokyo MoU, with port state control carried out by the China Maritime Safety Administration. Inspectors look at structural condition, corrosion in accessible spaces and the state of the fire main and other safety-critical piping, so a superintendent with a doubtful deck area or a wasted fire main is better served gauging and repairing before arrival than explaining it at the gangway. China also applies its own domestic emission control rules in coastal and inland waters, including limits on open-loop scrubber wash-water discharge in some areas, and ships trading between Shanghai and the Yangtze river ports have to plan scrubber operation around them.

That matters for inspection because scrubber wash-water and overboard piping sees heavy, uneven service: long periods in open-loop mode at sea, then closed-loop or idle spells near the coast. Erosion and corrosion in those lines, and at the overboard penetrations in the shell, are a known source of leaks. Shanghai is also a centre of Chinese ship leasing, and a lessor taking a ship back at the end of a bareboat charter needs a condition record as much as an owner buying second-hand. An independent, well-documented thickness survey serves both.

Wherever a ship is outside a sulphur emission control area, the global 0.50% sulphur cap applies, and many of the ships calling at Shanghai meet it with an exhaust gas cleaning system rather than compliant fuel. Scrubber wash-water piping, the overboard discharge and the hull penetration around it corrode quickly in service, especially on open-loop systems, and are worth adding to the gauging scope.

How a thickness measurement job runs at Shanghai

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

Most teams land at Shanghai Pudong International Airport; Hongqiao is useful for domestic connections to the upriver yards. Yangshan is reached by road over the Donghai Bridge, and terminal access is through port passes arranged by the ship's agent; anchorage boarding depends on a launch the agent times to the ship's position in the estuary. Technicians travel on Chinese business visas, and the application normally needs an invitation letter from a company in China, so we start the paperwork as soon as the berth, anchorage window or dock date is confirmed rather than waiting for the final ETA.

• 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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