Wrongly applied and poorly maintained cargo hatch covers and sealing systems increase the risk of cargo becoming damaged by water. The most common wet cargo problems include leaking cross joints, and compression bars, rubber gaskets, hatch coamings, drain channels and cleats in poor condition.
The importance of continually maintaining seal integrity must take a more prominent position in ship maintenance scheduling as demanded by regulations:
SOLAS Reg II-1/11.1 it states that hatches and watertight seals must be regularly tested: “Where a hose test is not practicable [sic] it may be replaced by [sic] an ultrasonic leak test or an equivalent test. In any case a thorough inspection of the watertight bulkheads shall be carried out.”
How have hatch covers been tested traditionally?
Chalk testing is used traditionally for visual inspection of the compression integrity of doors and hatches on vessels that hold the potential for flooding. Chalk is applied evenly around the knife edge, coaming compression bars or panel cross seams of doorways. The door/hatch is then closed and sealed. Once re-opened the rubber gasket which pushes against the knife edge is visually inspected for the chalk line. Any breaks in the chalk line indicate a lack of compression in that area. It must be noted that chalk testing is NOT a leak test, but only provides an indication of potential compression issues
Why are these methods no longer recommended by P&I clubs?
Various drawback come with chalk and hose testing, for instance;
Both of these hatch cover maintenance tests are time-consuming and sometimes completely impractical. Some circumstances have been highlighted that prevent this test from being conducted such as the hose test if dry cargo is within the hold being tested but these tests conducted at port or in dry dock will never reproduce conditions when the ship is at sea and therefore cannot expect to achieve the same standard. Claims resulting from water damage due to leaking hatch covers still contribute a huge part of the overall loss figures on dry cargo ships. This method is neither accurate nor time effective.
What is the alternative?
The Swedish P & I club recommend using Ultrasound. As stated in their 2018 report “A much more effective method is to use an ultrasonic device, which is designed for this purpose and can pinpoint the area which is leaking, and if the compression of the gasket is sufficient. The advantages of using this type of equipment are evident, since ultrasonic tests can be carried out during any stage of the loading without risking cargo damage. The test can also be completed in sub-zero temperatures. The ultrasonic test should be carried out as per the class requirements.”
Ultrasonic testing is a dramatically more sensitive, accurate and reliable method for testing cargo hatch covers, bulkheads and doors for watertight integrity on all vessels. A multi-directional ultrasound emitter is placed in a hold. The opening being tested is then sealed and the receiver switched on ready to receive any leakage of ultrasound via a set of headphones. An increased reading of ultrasound signal signifies an issue with the integrity of the door/hatch. Further, and closer inspection will allow identification of any specific leakage sight along with the severity. This test will take approximately 10 minutes and requires only one operator. watertight compartment doors testing