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BARBAROS DENIZCILER DERNEGI
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Cygnus Instruments Ltd
Paul Fahy
Introduction to ultrasonic hatch cover testing
www.cygnus-instruments.com
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
ROV mountable
thickness gauges
2000 m and 4000 m
depth rated
designed for safely
measuring metal
thickness in
potentially explosive
environments
Cygnus 2 Hands Free
Designed for use in rope
access surveys
Product Overview
Cygnus Dive is the latest innovation
from Cygnus Instruments and is a
wrist-mounted underwater
thickness gauge...
Cygnus Hatch Sure provides a
quick and effective method of
evaluating hatch cover seals
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
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
Why does anyone need to
buy a hatch tester
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)
Ultrasound in a cargo hold
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
Hatch-Coming & Hatch Cover
Do
Fig 7.1 Transmitter Centrally Positioned.
Hatch coaming & covers
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
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
Telescopic Extension
Hatch Sure
Transmitter
Neckband
Headphones
Remote
Microphone
Hatch Sure
Receiver
Worn by Surveyor – Outside Cargo Hold Inside Cargo Hold
Remote
Control to
Transmitter
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
Neck and waist
straps - for
convenient, safe,
hands-free
operation
Supplied in
weatherproof
case
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
Tanktop
Open Hatch Gap
Hatch Covers
Deck
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
5%20%
33%18%
11%
8% 5%
Pipe Failure in Hold Cargo or documents faulty
Hatch Cover Leaks Ships staff fault
Engine room problem Cargo Stowage problem
Strucural fault
Cargo - Di-Ammonium Phosphate (fertilizer), totalling about 27,000 mt.
Voyage - Morocco to China.
Damage - Claim
Case 1:
Case 2:
Cargo - Steel products.
Voyage - China to Flushing, Holland.
Damage - Ultrasonic test of hatches revealed leakages at the corners
of cross joints of the hatch covers.
Claim -
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.
Some of our Customers
Ship Owners/Managers