Ultrasonic testing and leaking hatch covers
Cargo damage due to water ingress through leaking hatch covers remain an important part of cargo claims. Non-weathertight hatch covers are the main cause of wet cargo damage. Therefore, P&I clubs require vessels to always maintain hatch covers in a weathertight condition. It is also the statutory requirement for weathertightness in the International Convention on Load Lines, 1966:
"Weathertight in relation to any part of a ship than a door in a bulkhead means that the part is such that water will not penetrate it and so enter the hull of the ship in the worst sea and weather conditions likely to be encountered by the ship in service".
Ultrasonic testing (UST)
Testing of vessel's hatch covers for weathertightness can be performed by different methods. The most common ones are hose tests and UST. Weathertightness can also be checked by light test, chalk test, air test and putty or moulding test. However, UST is the only way to generate measurable result, which is necessary to decide whether the condition of hatch covers is acceptable.
UST should be carried out by qualified surveyors. Surveyors must complete a UST operational course by an ultrasonic producer and obtain an ultrasonic operator certificate. Ultrasonic equipment is calibrated by authorised company or manufacturer. The assigned surveyors must present their UST operator and calibration certificates.
Ultrasonic equipment uses sounds with frequency above 20 KHz that cannot be heard by the human ear. The emitter of the sound is placed in the cargo hold and then activated. The UST operator will check for outside leakages in hatch covers and hatch coamings, and record them in the report.
P&I insurers accept the records of UST as it provides measurable and reliable results. UST is the only method that shows the degree of hatch cover leakage, which is crucial in determining whether the hatch covers are in an acceptable condition. The acceptable range of leakage is less than 10% of the open hatch value (OHV). If the hatch covers' leakage is more than 10% of the OHV, the club may insert a warranty in the certificate of entry. All claims arising out of leaking hatch covers will not be reimbursed by the club until the warranty is lifted. Members need to repair the hatch covers and request the club to arrange a follow up UST.
If the hatch covers' leakage is less than 10% of the OHV, the hatch covers are considered to be in a weathertight condition. This means water will not penetrate the ship through hatch covers in any sea condition (Load Line Convention), i.e. hatch covers are watertight.
Avoid high expansion foam
High expansion foam and sealing tape are commonly used in industry to ensure weathertightness of vessel's hatch covers.
However, for P&I Clubs, the use of high expansion foam and sealing tape indicates that the owners are aware of the potential leakage of the hatch covers. If the cargo receivers present such evidence, ship owners would be in a weak and disadvantageous position in cargo claim negotiations. High expansion foam and sealing tape also can give a false sense of security as it can be washed away by waves.
P&I clubs recommend owners to avoid using high expansion foam and sealing tape. The hatch covers should be well-maintained and its weathertightness should be ensured without additional measures.