What are test carried out to check weather tightness of hatch cover? |

What are test carried out to check weather tightness of hatch cover?

Following are test carried out to check maintenance of hatch cover –

  1. Ultrasonic Hatch Leak Detection.
  2. Water hose test.
  3. Chalk Test .
  1. 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.
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).

Advantages are as follow –

Reliable, Non-destructive, repeatable testing method.

  • 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.

Disadvantages are as follow –

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

Water hose tests are used to determine weather tightness of hatch covers. If correctly performed, hose testing will show hatch joints that leak.

The general procedure for hose testing is to apply a powerful jet of water from a 20-50mm diameter hose fitted with a 12mm diameter nozzle held at a distance of 1-1.5 metres from a hatch joint, moving along the joint at a speed of 1 metre every 2 seconds.

The drawbacks of hose testing are:

  • The hold needs to be empty;
  • It cannot be performed in sub-zero conditions;
  • It requires the deck scupper drains to be open (potentially causing pollution);
  • The test cannot pinpoint leaks on the cross-joint or side joint accurately;
  • Two people are needed to supervise the test.
  1. Chalk Test –

When performing a chalk test, the top edge of every compression bar is covered with chalk. Hatches are then fully closed and reopened. The rubber packing is examined for a chalk mark, which should run continuously along the packings centre.

Gaps in the chalk mark indicate lack of compression. Chalk testing merely indicates if hatch panels are aligned and compression achieved.

It will not show whether compression is adequate and therefore it is not a test for weather tightness

 

manish-mayank

 

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