ROVworld Subsea Information

Class Instrumentation Lead the Ultrasonic Revolution
Date: Tuesday, April 26, 2011 @ 03:06:19 EDT

Class Instrumentation LtdApril 2011 - Class Instrumentation, a London, UK based company was invited to attend the NAMS Global Marine Surveyors Conference in St Louis, Missouri earlier this month. Ken Hawes, Technical Director at Class Instrumentation and a world-renowned expert in ultrasonics, spoke on Ultrasonic Hatch Cover Testing and met with a very attentive audience. He demonstrated the benefits of ultrasonic testing with the Cargo-Safe™ Ultrasonic Hatch Cover Tester over other methods of hatch testing, such as hose and chalk.

Historically, the hose test has been used to indicate the water-tightness of a cargo hatch by using a high pressure hose directed along the joints and seals of a hatch cover. An observer is present in the hold to check for water ingress. The limitations of this method are that it can only be done with an empty hold, necessitates the removal of crew from the decks, does not precisely indicate points of leakage and cannot be conducted in sub-zero temperatures. The overwash resulting from the hose can also have environmental implications. Likewise, chalk testing simply indicates if there is contact between seals and does not indicate water tightness. Ultrasonic testing is not affected by any of these conditions and is now the method of testing preferred by many P&I clubs.

The principle for ultrasonic hatch cover testing is simple. After the hatch covers are closed, the transmitter generating an ultrasonic signal is placed in the cargo hold (empty or loaded with cargo). The surveyor then uses the CARGO-SAFE™ ultrasonic receiver to ‘listen’ from the outside of the hold and detect any ultrasound that passes through holes in the hatch cover sealing system with pin-point accuracy.

Class Instrumentation also exhibited their range of ultrasonic testing and NDT equipment designed to improve safety and benefit the marine industry.

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This article comes from ROVworld Subsea Information

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