The integrity of a watertight structure is critical. Bulkheads and cable transits must operate as intended to allow for compartmentalisation in the event of water ingress, but the harsh, saline and turbulent maritime environment renders the seals in these cable transits or watertight hatches prone to corrosion and deterioration. Therefore, watertightness monitoring and hatch cover testing should be conducted regularly, using a reliable and simple means.
Excessive water ingress can pose a significant risk even to the extent of losing lives and vessels. Water ingress through supposedly weathertight structures is common and has significant implications. The failure of a weathertight hatch may occur because of the failure of an inexpensive seal, which is easily and cheaply replaced, but the issue is locating these instances of seal failure or a lack of integrity across numerous such parts installed on a vessel. In this blog, we will discuss the different methods of hatch cover testing and the advances in ultrasonic watertightness testing.
Traditional Chalk Testing: Strengths And Limitations
The chalk test is a simple and effective method of hatch cover testing. This test is an essential part of the routine maintenance of ships. Regular inspection and maintenance of hatch covers can help prevent accidents and damage which can be costly.
A ship’s crew or a marine surveyor can conduct the chalk test independently or as part of a combination of tests. A thin layer of chalk is applied to the compression bars. The crew then closes and secures them, as per the ship’s procedure. The crew then open the hatch and visually assess the chalk marks. If there are breaks in the chalk marks, the hatch is not watertight and the crew should investigate further.
The reliance on visual inspection means that this method maybe insufficient for modern vessels. Visual inspection is highly subjective making the results unreliable and it cannot identify microscopic defects which are common causes of water ingress. Chalk lines are also susceptible to influence from the weather. Therefore, crew or surveyors must conduct the test when the risk of weather influence is relatively low. All of which means that the chalk test cannot provide a comprehensive assessment of the watertight and weathertight integrity of hatch covers.
The Growth Of Ultrasonic Technology – A Technological Leap!
Ultrasonic watertightness testing is one of the most effective ways to ensure safety at sea and assess the weathertight integrity of your vessel without causing any damage. In simple terms, this technology works by using the behaviour of sound at boundaries between different materials. Sound travels easily through the air, but when it hits a solid material, most of it is reflected or absorbed, with very little passing through. Typically, this can be a problem for ultrasound-based technology. In this case, it helps us detect even the smallest leaks in solid seals with great accuracy.
Ultrasonic hatch cover testing is clean and poses not threat of contamination to sensitive cargoes. Instead, it actively contributes to reducing the risk of contamination by facilitating regular integrity testing. Ultrasonic watertightness testing is the best solution to ensure marine safety, minimise cargo damage, and optimise the safe operation of a ship at sea. While the chalk test lacks quantitative data, ultrasonic testing allows for precise identification and quantification of leak points. This enables you to undertake timely maintenance and repair actions to maintain watertight integrity and prevent potential hazards.
Why Are Ultrasonics The Future Of Hatch Cover Testing?
IMO SOLAS Reg II-1/21.3 states that “The watertight doors and all mechanisms and indicators connected therewith shall be periodically inspected at sea at least once a week.”
Conventional hatch covers tests such as the Chalk test and Hose test make complying with this regulation difficult and time-consuming. These tests require multiple operators, are subject to weather conditions or a cargo hold being emptied, and in the case of the hose test, is messy.
By contrast, our ultrasonic watertight integrity monitors are portable, handheld, and easy to use. Therefore, one person can conduct inspections with minimal training. The results of which will provide you with an exact location and a value of the severity for the leak. Furthermore, a single operator can non-invasively test a large number of hatches or seals consecutively. This allows you to conduct weekly inspections faster and with greater efficiency while providing with more accurate and reliable results. Ultrasonic testing is the most cost-effective way to ensure the watertight integrity of your vessel.
Ultrasonic hatch cover testing is also the only recognised method of determining weathertightness in hatch covers by P&I Clubs around the world. Additionally, our Portascanner® range meets Classification Society requirements for watertight integrity test equipment. The two most relevant Classification Society requirements are DNVGL-CP-0484 and IACS UR Z17.
DNVGL-CP-0484 relates to the service supplier (the company conducting the ultrasonic watertight integrity test) and lists the exact requirements of the equipment that needs to be used. This is in Page 13 and 14 (Chapter 2).
As an example, we have listed below an extract of these requirements, and our Portascanner® range complies with all of these:
- The transmitter shall provide a uniform open hatch value (OHV) over the tested area.
- OHV shall be adjustable to a stable value allowing maximum sensitivity without false side effects.
- The receiver shall be provided with an audible signal and a visual readout, calibrated in decibel.
- Laboratories authorised by the manufacturer must carry out biannual re-calibration tests.
- A fail/pass criterion must be applied in tightness testing.
How To Choose The Right Hatch Cover Testing Solution For Your Vessel?
The context in which the test needs to be completed predominantly dictates which hatch cover testing solution is best for you.
Crew can only conduct the Hose Test while the vessel is dry docked and the cargo-hold is empty. Therefore, you cannot use this method to assess watertight integrity while at sea. Moreover, the Chalk test does not provide a scientific or reliable assessment of the weathertightness or watertightness of a hatch. Ultrasonic hatch cover testing is the only test that you can use in a plethora of situations. It will provide accurate and reliable results each time.
Our Portascanner® range comprises the Portascanner® WATERTIGHT PLUS and the Portascanner® WATERTIGHT PRO.
For standard watertightness testing, the Portascanner® WATERTIGHT PLUS is the ideal solution. If you require more precise quantification and record-keeping, the Portascanner® WATERTIGHT PRO may be of interest.
- The Portascanner® WATERTIGHT PLUS, has ABS Type Approval and RINA Classification Society Acceptance. It is an industry-approved solution to watertight integrity testing and regulatory compliance. The device conveniently reports leaks as decibels (dB) and as a percentage Open Hatch Value (%OHV). This makes it easy to assess the integrity of the hatch cover and your regulatory compliance by calculating the key figures automatically.
- The Portascanner® WATERTIGHT PRO is perfect for assessing repairs and for reinspection. The device allows you to photograph a test site before testing. This then allows you to plot the exact leak location. It also calculates the flow rates of individual leaks, as well as an overall leakage rate, for each hatch and can relate these rates to compliance requirements for watertightness and weathertightness. This makes it highly convenient and easy to use, giving you complete confidence in the integrity of your vessel.
If you would like to find out more about our Portascanner® range, please contact our team.
The Future Of Watertightness Testing In The Maritime Sector
In 1989 IACS introduced its guidance to owners concerning the care and survey of hatch covers as follows:
“Loss of weather-tight integrity continues to be a constant factor leading to cargo damage which could result in a threat to the safety of the crew, the ship and its cargoes, despite advances in modern shipbuilding technology, construction, navigation and means of preventing ingress of water into hold spaces.”
There has been little change over the intervening years. Existing methods of testing, such as visual inspection, chalk compression testing, and hose testing, have failed to solve the issue of watertight integrity.
Ultrasonic watertightness testing is uniquely able to solve a range of problems with tradition methods of integrity testing. The maritime industry must embrace these advancements to ensure the safety of lives at sea and the integrity of their vessel.
We are committed to continuing to innovate in this field and ensuring the safety of those at sea. Our customer relationships are central to our operations. We actively work with global navies, shipping, and offshore energy companies worldwide to implement an ultrasonic programme to “see the sounds that others cannot hear” in watertight integrity.
This is what enables Coltraco Ultrasonics to be global leaders in ultrasonic instrumentation.
