Methods to Check Water Tightness of Hold Covers.
1. Hose Water Test:
In this test a water spray from a nozzle of 12mm diameter is sprayed over the joint of hold and cover from a distance of 1m to 1.5 m with a pressure of 0.5 m/ second water jet.
The limitation or drawbacks of this test is that it requires two persons and hatch cover to be tested must be empty.
The leakage if very minimal cannot be identified by naked eye and cannot be performed in sub zero or cold weather.
2. Ultrasonic Test:
The Ultrasonic testing is a more accurate method of testing water tightness of hold and its cover. In this system an ultrasonic generator is kept inside a closed and intact cargo hold.
A sensor of that unit is passed all over the compression joint and any low pressure area or point detected by the instrument can be a leakage point.
Few drawbacks of this instrument is it is not normally kept on board and qualified person is required to perform this test.
3. Chalk Test:
This is the oldest or most traditional method for testing hold cover compression, but it cannot test the water tight integrity of the hold.
A layer of chalk powder is applied all over the steel back of the hatch and then the hatch cover is closed and tightened to its normal values.
The impression of chalk on the rubber packing is then studied to check lack of compression point shown by gap in the chalk marks.
We provide this information because we supply everything related with hatch cover.
IJIN MARINE LIMITED