Sea water ingress is one of the major sources of damage to cargo resulting in expensive insurance claims.

Hatches leak for a variety of reasons, but mainly because of poor maintenance or failure to close them properly. Leaking or badly maintained hatch covers can lead to more serious consequences than wet cargo resulting in flooding, accelerated corrosion or even loss of vessel.

Ultrasonic Hatch Leak Detection

Ultrasonic hatch leak detection is a viable alternative to the hose test for testing hatch covers, access doors and access hatches for weather tightness, as it accurately locates potential points of leakage. This test should only be carried out using Class Type approved equipment such as Cygnus Hatch Sure and approved test procedures.

The ultrasonic hatch leak detection involves placing an electronic signal generator – transmitter inside the cargo hold with closed and secured hatches. A sensor is then passed around the outside of all compression joints. Readings taken by the sensor on receiver indicate points of low compression or potential points of leakage. The criterion for tightness has been set at 10% of the OHV (Open Hatch Value).

Ultrasonic testing overcomes the majority of limitations associated with hose testing and can be carried out when holds are loaded.
Advantages (when using Class Type approved equipment):

• Reliable, Non-destructive, repeatable testing method.
• Allows detection of areas where lack of compression or contact exists with pin-point accuracy (no time consuming investigation needed for finding the leaks, as the area of the leak can be pin-pointed local repairs might be sufficient and adequate,….).
• Gives indication about compression.
• Allows quick and easy testing, without assistance from ship’s crew (except for supervision and safety aspects).
• Can be used in holds loaded with water susceptible cargo.
• Can be carried out irrespective of weather conditions.
• Can be used for weather tightness and air/gas tightness.
• Allows to identify leaks without the use of a transmitter, on condition that the compartment tested for leaks is pressurized (air escaping through small openings, cracks etc… will cause disturbance of molecules which creates ultrasounds that can be detected).

Drawbacks:

• Requires ultrasonic test equipment and suitably trained operators.
• Requires Class Type approved equipment to be used when acting as class service supplier.

Narval tightness testing teams use Cygnus Hatch Sure Ultrasonic Leak Detectors and are trained by Cygnus.