Vessel owners and managers alike need to ensure that hatch covers seal well and are for all effect weather tight. In the event that the cover hatches leak, any cargo stowed inside the holds could be damaged and in extreme instances where an abundance of water (rain or green water) makes its way into the holds, it can be even detrimental to the vessel’s stability.
How is it done?
Our in-house certified team at Vassallo Associates uses a portable tool to locate a leak site in any watertight seal and indicate its extent using both audio and visual headphones. LCD screen). It is a lightweight unit that allows surveyors and inspectors, through the use of ultrasonic methods, to inspect the watertight integrity of ships’ hatch covers, holds, bulkheads, multiple cable transit areas, watertight and weathertight doors and any other holding vessel or water-tight compartment.
Due to its use of ultrasonic methods, we may operate our ultrasonic tool during the loading and unloading of cargo, hence saving both time and costs. Crucially it may also be used without the risk of creating a mess or harming cargo, unlike chalk or water pressure testing. In addition, the risks of environmental pollution from water run-off and non-compliance with port state rules are entirely eradicated.
All sound is physical vibrations that move through a material and in the case of the sound we are used to, the vibrations move through the air. Ultrasound is the same as the sound we experience, but its frequency is beyond that which humans are capable of hearing.
How a leak is detected?
The Ultrasonic Tool is used to locate the site of a leak. In order to do this, the generator is placed on one side of the hatch or door and emits a specific frequency of ultrasound which the receiver detects on the other side. If there is a leak site, a hole in the seal, for example, the receiver will be able to detect an increased ultrasound signal when scanned over this site. The receiver indicates a leak site via an audio signal emitted through the headphones, with an increase in the digital display readout and the movement of the bar detection graph on the visual display. The extent of the leak may also be determined as the larger the leak the larger the audio signal heard and the larger the readings on the display.
Watertight vs Weathertight?
This is determined according to the strength of the signal that is received from the generator on the other side of the hatch. As a rule of thumb, if the surveyor receives more than 10% of the Open Hatch Value on the sensor wand, then the seal is generally weak. If the signal received is less than 10%, then it is considered weathertight. If the signal is even less, then the hatch is treated as watertight.
Contact us now to discuss your surveying requirements and schedule ultrasonic hatch cover tightness testing.