How have seals been tested traditionally?

Coltraco Commitment To :

  • Through-life maintenance support
  • We still maintain units built 20 years ago
  • Extend trade-in credits - replace old units for new
  • UL listing & ABS type approval - Portalevel™ MAX
  • ABS type approval & RINA approval - Portascanner™
  • Be a life-safety technology partner – Permalevel™
  • Certified OEM calibration & ODA service stations

Coltraco manufacture Ultrasonics That Work

How have seals 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

The International Association of Classification Societies states that a chalk test must be followed by a hose test. The hose test is used in conjunction to determine the weather tightness of doors and hatch covers. The spray from a nozzle of 12mm diameter is sprayed from a distance of 1 to 1.5 meters with a water jet pressure of 0.5  ms-1  This test should help identify any leakage from the hatch joints, although the exact location of the leakage sight cannot be pinpointed. Various drawback come with this test, for instance;

  • The hold is required to be empty as cargo can be damaged by water. This is not always possible and certainly poses more issues once the ship is laden with goods. 
  • The test requires drains to be opened posing a genuine pollution risk. 
  • Two people are required to carry out the test effectively. 
  • Cannot be performed in sub-zero conditions.
  • Water pressure and distance can affect results.
  • Time-consuming.

 

Both of these 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.

The accuracy of results is open to human error. The application of the chalk must be very accurate in order to avoid misdiagnosis. A false application of chalk could be construed as a compression issue.

In fact, the limitations of using chalk and water hose testing have been demonstrated in case studies from the Swedish P&I Club’s Recent Report:

CASE STUDY 1: 

Before loading with grain the cargo hatch covers had passed a water hose test. Once the vessel was fully loaded the cargo hatch covers were then sealed with tape. The cargo was mostly damaged underneath the cross-joints. During the voyage the vessel encountered heavy weather at Beaufort scale 10 with large waves and a swell which covered the hatch covers in water.  A visual inspection of the cargo hatch covers, rubber gaskets, securing devices, valves, ventilators and drainage channels found them to be in order. During the voyage the tape by the cross-joints between the forward and aft hatch panels of two holds had peeled off. A chalk test was carried out and this did not show any imprints on the rubber gaskets. At the discharge port it was found that part of the top layer of the cargo in a number of the cargo holds was damaged by seawater. Further investigation revealed that there was no contact between the compression bars and rubber gaskets on the cross-joint panels. In addition, an ultrasonic test identified that the cross-joints between the forward and aft hatch cover were also leaking. 

CASE STUDY 2:

A vessel had loaded wire coils. After loading was complete the crew taped across the transverse beams of all the cargo holds.  The vessel sailed through heavy weather that lasted for about two days. During this time the vessel was pitching and rolling heavily. The cargo hatch covers were covered in water.  When discharging at the destination port it was found that the steel coils in the top tiers were corroded. The coils below the centre line and folding seams were the most affected.  The surveyor tested the water integrity of the cargo hatch covers with an ultrasonic device which detected significant defects to the sealing arrangements. 

  • The surveyor found the following defects: 
  • The gaskets were in poor condition 
  • The non-return valves were clogged and the ball inside was not moving
    The transverse packing on the hatch covers was leaking
  • There were some cracked corners and leaking
  • The ventilation covers were leaking

 

CEO Message

Integrity and Science Key to Our Culture of Performance

Dear Coltraco Customers, Strategic Partners and Distributors,

Integrity is our defining value. Performance is its consequence. We understand that our customers have choices, and how we perform determines whether customers choose us. Coltraco’s Code of Ethics does not merely require compliance with laws. It embodies a Commitment to positive behaviours that build trust, promote respect, operate with distinction, with courtesy and global levels of performance, demonstrating our integrity and delivering customer performance.

We honour our commitments, communicate transparently, and act with honour. Ethics are the foundation of our performance culture and our science-based approach. We lead in specific technologies delivering the watertight integrity monitoring of marine structures and the monitoring of fixed liquefied gaseous fire extinguishing systems and the room integrity of protected space to ensure agent hold-times post-installation. We show this by our understanding of the science in them and the mathematics that explain them.

I would like to thank you for your business and for the relationships with our Customers, Strategic Partners, Distributors and ODAs who we value so highly.

My kindest regards,
Carl

Carl Stephen Patrick Hunter BA(Dunelm) Hon DSc FRINA FIMarEST MRAeS
CEO & Managing Director
Coltraco Ultrasonics Limited
46-47 Mount Street, Mayfair, London W1K 2SA
United Kingdom

Tel:  +44 20 7629 8475
Fax: +44 20 7629 8477

Call Now : +44 207 629 8475

 

References in PDF Format

 

Underwriters LaboratoriesUnderwriters Laboratories

 

Reference Alpha Fire UK Portalevel MAX Sept 2012

Reference Portascanner-II CSD MOD Albion and Bulwark

Quotation.

Quotation

Support.

Support

About Coltraco Ltd.

About

 
 

Request a Quotation

Online Submission

Click Here

Call: +44 207 629 8475
Our customer support line is open during UK
business hours
Mon-Friday, 9.00am - 5.00pm GMT

Email: sales@coltraco.co.uk
Enquire via email and a dedicated
member of the sales team will deal
with your request personally.

Cookies make it easier for us to provide you with our services. With the usage of our services you permit us to use cookies.