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Tanker Shipping & Trade

Ultrasound is more accurate than chalk when testing watertight doors

Tue 15 May 2018 by Craig Jallal, tankers and markets editor

Ultrasound is more accurate than chalk when testing watertight doors
Credit: Hervé Cozanet via Wikimedia Commons

The traditional method of testing watertight doors and fittings should be replaced with modern techniques such as ultrasound, according to a report on watertight doors from the Swedish P&I Club. Fellow P&I Club, Gard, has also released a video highlighting the importance of the correct use of watertight doors.

Watertight doors and inspection hatches are essential for access and smooth the daily running of any vessel. The sealing of the fittings has to comply with SOLAS Reg II-1/11.1. The traditional methodology is for chalk to be applied evenly around the knife edge, coaming compression bars or panel cross seams of doorways. The door/hatch is then closed and sealed.

Once re-opened, the rubber gasket which pushes against the knife edge is visually inspected for the chalk line. Any breaks in the chalk line indicate a lack of compression in that area. It must be noted that chalk testing is NOT a leak test, but only provides an indication of potential compression issues.

The International Association of Classification Societies states that a chalk test must be followed by a hose test. The hose test is used in conjunction to determine the weather tightness of doors and hatch covers. The spray from a nozzle of 12 mm diameter is sprayed from a distance of 1 to 1.5 m with a water jet pressure of 0.5ms-1.

Various studies have shown that these test can be inaccurate, and are lengthy to conduct. According to ultrasound equipment manufacturer, Coltraco, a portable ultrasound scanner is both quicker and more accurate.

The ultrasound generator emits a modulated signal of a specific frequency of ultrasound (in most cases 40,000 Hz). The receiver then picks up the signal and converts it into a result indicating watertight integrity. Devices such as the Portascanner® WATERTIGHT allows crew members to check for failing seals while at sea which allows for prompt maintenance.

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