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Cygnus Instruments Ltd Paul Fahy Introduction to ultrasonic hatch cover testing

Introduction Welcome to Cygnus Instruments The pioneers in developing multiple echo technology for material thickness measurement through coatings. For over 25 years. Cygnus ultrasonic thickness gauges which are employed in almost every industrial application around the world. With successful diversification, Cygnus now carries three ultrasonic product lines - thickness gauges, hatch cover leak detectors and industrial leak detectors.

Product Overview

designed for safely measuring metal thickness in potentially explosive environments

Cygnus 2 Hands Free Designed for use in rope access surveys

ROV mountable thickness gauges 2000 m and 4000 m depth rated

Product Overview

Cygnus Hatch Sure provides a quick and effective method of evaluating hatch cover seals

Cygnus Dive is the latest innovation from Cygnus Instruments and is a wrist-mounted underwater thickness gauge...

Hatch Sure Cygnus Hatch Sure is a Classification Society Type Approved, ultrasonic system for rapid and thorough testing of the weather tightness of cargo hatch covers. A single operator can use the device. It does not interfere with any other vessel operations when in use. Supplied with traceable calibration certificate & 3 year warranty

Why does anyone need to buy a hatch tester Ultrasonic testing has proved to be the most reliable method of assessing the condition of seals on a hatch cover. Clean Fast Non polluting

Detection of defective seals prevents damage to cargo and saves time for all interested parties. Potential savings can be hundreds of thousands US$ per vessel Leaking hatches are the largest single cause of insurance claims

Saves money

Presentation Outline Principles of the Technique: Principles of sound

Overview of ultrasonic hatch cover testing

The Product: The kit and the parts

The operation of the equipment

Operation of the System: Setting Open Hatch calibration value

Testing for leaks

Why and How is Ultrasonic testing relevant?: Owners obligations

Case Reference: Cargo Claim

What is Ultrasound? Ultrasound is a sound wave beyond the range of human hearing

The normal range of human hearing is between about 20Hz and 20kHz, but the range becomes less as we get older. Sounds with frequencies above about 20kHz are called ultrasound.

What does it look like? Ultrasound energy travels in straight lines from the 19 transmitter elements, each forming a cone-shaped beam as it moves away from the transmitter

Transmitter Beam Spread Pattern (side view)

Hatch-Coming & Hatch Cover

Ultrasound in a cargo hold Hatch coaming & covers


Fig 7.1 Transmitter Centrally Positioned.

Ultrasound travels through air and is reflected from all hard surfaces so that in the enclosed hold, reflections of ultrasound bouncing off the sides evenly distribute the amount of measurable ultrasound

Ultrasonic Testing If a cargo hold is not perfectly sealed, some ultrasound will leak through the gaps to the outside An ultrasonic receiver is used to find those leaks from the outside

Why Ultrasonics? This method of testing hatch covers has the following advantages:

Reliable, accurate, rapid and repeatable

No pollution

OK to carry out after cargo loaded - vessel in sea-going condition

OK in different light conditions and sub-zero temperatures

 Also test cargo access areas (bow, side & stern doors) or any opening that needs to be sealed

Cygnus Hatch Sure Kit (2.5Kg)

System Overview Battery-powered transmitter with 19 x 40 kHz ultrasound emitters, produces an omni-directional sound field, which is distributed throughout the cargo hold The receiver part of the system displays the sound energy level that passes through gaps in the enclosed cargo hold, to enable the location of leaks to be quickly and accurately identified Neckband Headphones Hatch Sure Receiver

Hatch Sure Transmitter

Remote Control to Transmitter

Telescopic Extension

Remote Microphone

Worn by Surveyor – Outside Cargo Hold

Inside Cargo Hold

The Transmitter Supplied in a pouch for protection When in use, secure open the pouch lid to expose the array of emitters

Shoulder strap (not shown) fits to pouch for carrying or to suspend transmitter against a flat, vertical surface if required to test a door or window Sling with 4 anchor points is supplied for suspending the transmitter unit in the cargo hold (if hold contains cargo such as grain or if no convenient surface)

Transmitter Controls

Power On/Off switch turns the transmitter power on and off! Remote ON: enables remote control of transmitter from the receiver

Remote OFF: transmitter operates continuously when the power is on LED flashes when in operation: flashing GREEN LED = batteries are good flashing RED LED = battery voltage is insufficient for reliable operation

The Receiver

Supplied in weatherproof case

Neck and waist straps - for convenient, safe, hands-free operation

Receiver Display

Receiver Keypad OH dB





Volume increase


Volume decrease

What is “Open Hatch�? Open Hatch Value = the ultrasound signal level measured by the receiver when the hatch cover is fully or partially open (or through an access hatch) This measured signal level (in dB) is then set to indicate 100 % Open Hatch (OH) When looking for leaks, the percentage scale is simple to understand and provides a means of assessment for the severity of a detected leak, since: ANY LEAK > 10 % OPEN HATCH (OH) = THE SEAL IS NOT WEATHERTIGHT Open Hatch Gap Hatch Covers



To set the Open Hatch Value one hatch cover is partially opened so the inspection microphone can be inserted into the gap directly above the transmitter

Listening for Leaks

1. After the Open Hatch value has been set 2. Close hatch covers and access hatches 3. Wear the headphones and scan along the joints and seals with the microphone 4. Once the ultrasound has been heard the surveyor can stop, home-in on the area and pinpoint the leaky section, then chalk mark it clearly as a leak

Product Training

PRODUCT TRAINING: Cygnus Instruments Ltd and its Authorised Distributors provide certified product training on the operation of the Cygnus Hatch Sure equipment.

Offers consistency of equipment use throughout an organisation and provides reference documentation for auditing and additional in-house training

Chart highlighting some of the common causes of damage, loss and personal injury associated with cargo holds and hatch covers "Cause of Large Cargo Claims by Value" Dry Bulk and General Cargo Vessels 8%


5% 20%


18% 33% Pipe Failure in Hold Hatch Cover Leaks Engine room problem Strucural fault

Cargo or documents faulty Ships staff fault Cargo Stowage problem

Case 1: Cargo

- Di-Ammonium Phosphate (fertilizer), totalling about 27,000 mt.


- Morocco to China.

Damage -


Case 2: Cargo

- Steel products.


- China to Flushing, Holland.


- Ultrasonic test of hatches revealed leakages at the corners of cross joints of the hatch covers.



Some of our Customers Ship Owners/Managers The widespread acceptance of the advantage for each vessel to have it’s own ultrasonic hatch cover tester is proven to reduce hatch maintenance costs and the number of claims.

Thank you Cygnus Instruments Ltd Paul Fahy

Cygnus Hatch Sure Sales