Happy 2019!

Post card picture of a Damen CSD500 at work.

Happy New Year! First of all, I would like to wish you: health, happiness and a year full of dredging action. And there will certainly be some dredging action. We will start this year with closing our ¡VAMOS! project and we will close off with another CEDA Dredging Days1, just as with which this blog started one year ago with a new year’s resolution.

Further topics will include the upcoming WODCON conference in Shanghai2, more CEDA Dredging Management Commission, some interesting book reviews and whatever happens along the way. Maybe I can get back on working on articles that explain interesting phenomena in dredging technology. Or just some funny experiences I had in our beautiful profession. There are so many memorable moments worth sharing for the general benefit.

And George Santayana has warned us to learn from the past: ‘Those who cannot remember the past are condemned to repeat it.’3 I don’t fancy that this site will be a monumental source of reference for posterity. There are much better institutes to store and share dredging knowledge. e.g. the CEDA comes to mind. It’s ‘a forum for all stakeholders involved in the dredging industry’4 and there are many working groups were the current knowledge is shared and stored in publications.

A much better place to look at a condensation of knowledge over a longer time span is the National Dredging Museum5. You might have noticed, that I am very fond of museums. I like to dwell through their expositions, relive the past and see the origins of current technologies. When I am trying to hatch some new sort of gizmo or gadget to perform a very peculiar dredging requirement, I can relate to all those branches of the technology tree, that are out there and see if there is something that can be combined in a new contraption.

Model of a ‘Krabbelaar’ or ‘Scratcher’ at the National Dredging Museum.

Sometimes you can recognize some technology in an exhibit, that was ahead of its time. Take this ‘Krabbelaar’ or ‘Scratcher’. It loosens the top layer of the sediment and expected it to flush out at the outgoing tide. Considering the enormous forces for cutting and internal friction, that have to be delivered by sail power, I doubt the production would make a viable business case. Nowadays, you would employ a dredge plough behind a tug6. Modern propulsion delivers the thrust needed for all requirements. Ploughing, scraping and smoothing has become much easier and modern hydrological simulations will give a better idea about the possible production and where the sediment will end up.

Example of a modern dredge plough, fitted on a Damen Stan Tug 1606.

Possibly our modern dredge plough technology will be surpassed by even better concepts. Maybe, regulations or fuel economy would direct us back again to a sustainable form of dredging management and the old scratcher makes a comeback in a modern form. And then, you know to find the origins in the National Dredging Museum.

I think, it is very important, we cherish our dredging heritage. For ourselves and for our posterity. Just as we support our trade associations, we should support the dredging museum. So, now I come back to my ‘new’ new year’s resolution: I will become patron7 to the National Dredging Museum. It is not much, but if it inspires you to do the same, we can make a difference together.

Collection of dredges.

References

  1. CEDA Dredging Days 2019, CEDA
  2. WODCON XXII, CEDA
  3. George Santayana, Wikipedia
  4. Our mission and strategy, CEDA
  5. National Dredging Museum
  6. Scrabster Harbour takes delivery of Damen Stan Tug 1606, Damen
  7. Sponsoring 2018, National Dredging Museum

See also

Ploughs, Beams and Rakes, IADC

 

 

 

Book Review: The World In A Grain

Cover page The World In A Grain by Vince Beiser.

Last Saturday, a special Dutch season started: Sinterklaas1. He traditionally arrives in a steam ship in some camera pleasing port and starts his tour through the country. Eventually he commemorates his name day (December 6th) by leaving presents for all children on the eve before. Usually this is celebrated with children and/or parents giving each other presents in elaborate packaging and clumsy rhymes. So, this might be a good occasion to recommend a book for your wish list.

Somewhere I found a copy of ‘The World in a Grain’ by Vince Beiser2. Actually, it was the subtitle, ‘The Story of Sand and How It Transformed Civilization’ that caught my attention. As you may have noticed, I am very interested in sand. And, it is good, to occasionally take a step back and contemplate how our product contributes to civilisation and the world as we know it.

Photo of American-Canadian journalist Vince Beiser (Credit: Wikipedia).

Vince Beiser3 is an American-Canadian journalist and the book is easy to read. The chapters are arranged to the subject where sand is coming from and its contribution to society. Beginning with the origin of sand, the erosion of rock, and the locations where it ends up and can be extracted. The most basic application of sand is construction sand to create infrastructure: reclaimed land, ballast material for roads and railways, general landscaping etc. Than, the applications become more refined: concrete, asphalt, fracking, foundries, glass making, eventually all the way to high end products as computer chips and smart phones. Each application requiring its own type of sand.

Soil sample exhibit at the Damen Dredging Experience.

Proceeding through the book, you will be surprised about how dependent we’ve become on such a small unit of our universe. And that is exactly where Beiser is alarming us about. Not only that at some point in the future, sand will become a scarce commodity, it already is. As with all scarce materials, they become precious and attract activity that is not always benefitting all stakeholders. This usually involves violence and crime. And Beiser has been exploring this dark side of the trade for his book.

His experience as criminal-justice journalist has helped him to uncover social injustice, where some greedy individuals were profiting from resources that ought to serve the wellbeing of all mankind. Beautiful beaches that have been scooped away. Rivers that changed their course and deprived communities from irrigation. Pastoral landscape, that was torn up and left behind devastated. He visited some sites and spoke to victims and activists. At some occasions, he was even threatened himself.

Progressing through the book, I even felt ashamed that I was taking part in an industry that allegedly rapes nature and deprives future generations of their rightful heritage. He reported severe cases from undeveloped countries, but even well-known names in our dredging industry have been mentioned. According to Beiser, there is no direct solution, as the demand is still on the rise, but I think there is: cooperation in governance. Share with others the experience on sand mining, the market possibilities and communicate with all stakeholders involved. Personally, I am involved in CEDA4, but there are many more platforms: IADC, EuDA, EMSAGG, PIANC etc. And as always: think about what you are doing and what does it leave future generations with.

OK, one last bonus link for those who don’t like reading a whole book. I think the producers of the Dutch children’s TV show ‘Buitendienst’5, last Friday, have been reading this book also.

Het grote zandmysterie (Credit: De Buitendienst).

References

  1. Sinterklaas, Wikipedia
  2. The World in a Grain, Amazon
  3. Vince Beiser, Wikipedia
  4. Dredging Management Commission, CEDA
  5. Het grote zandmysterie, NPO Zapp

See also

Options for Repairing Parts That Ought to be Replaced

Patching up a pump casing as crisis management

Summer is arriving. We’ve had lots of sunshine and thunderstorms with rain these days. For sunshine, you protect yourself with lots of sun screen with a high protection factor. If it rains, you put on a raincoat and wellies. So, if you want to protect what is dear to you, you cover it with the appropriate cover. Hmm, if your pump gets eroded by your mixture, you cover it with a protective layer. Right?

So, let’s see what options we have? Common solutions to protect the wear parts of the pump are:

  1. Vulcanise a rubber film over a new cast wear part. Usually, the pump parts are designed to receive an additional layer of several mm to a couple of cm. Astoundingly, the soft rubber, lasts longer than the hard alloy. This is due to the elasticity of the rubber. Impacting particles are bouncing back into the fluid and don’t damage the metal1. There have been several developments, where polyurethane2 can be a viable alternative to rubber with the same protective principle. Rubber and polyurethane have to be applied by specialised companies under controlled conditions. One warning though, rubber can be cut. When dredging shells or coral, the rubber is sliced to pieces and the flow peels away sheets of rubber or PU.

    Wear resistant elastic collision of rubber and PU
  2. Instead of the flexible rubber, also hard chemical compounds have been developed to be applied as protective layer. This layer can be applied on a virgin part, that can accommodate the layer by design, just like the rubber cover. Or it can be used to restore an already worn down part and extend the lifetime that way. The pastes have been engineered to be applied in the field: wet, rust, salt and dirt. As it easily applied, many owners are very fond of this solution. Although lifetime is not extended as much as the first option.

    Wear plate restored with chemical coating
  3. Another process for new builds and restoration is hard-facing3. On a suitable base alloy, the vulnerable surface is cladded by welding a layer of very hard metal onto it. The hard-facing can be much harder than the sand particles (Mohs remember) and that the added material is brittle as glass doesn’t matter as it is carried by a much more ductile base material. As the base material is also softer, once the hard layer is away, the wear rate will become unexpectedly rapid. Especially as such local wear spots tend to eat through the material, due to the increased turbulence. Special care should be taken, when the wear part is not completely covered in hard-facing, but only partially covered. The discontinuities are hot spots of wear. Discontinuities can also appear from the hard-facing itself. The different material properties of cladding and base material cause to be vulnerable to check cracking and flaking4.

    Warning: make sure you’re wear part can be welded, or it will crack

All three solutions are labour intensive. especially vulcanising and hard-facing takes many hours. And applying the wear paste has to be done more often. Even if labour is cheap in your operation, you still have to take it into account in your spare part strategy. More so, if you only rely on just one wear part and don’t have one on stock and the dredge is idle, you’ll lose a lot of money on income.

Another consideration might be the environment. An all metal wear part can be recycled easily. Rubber, PU and paste can be a pain to get rid of, responsibly.

Off course, I am an engineer at the manufacturing side and the above perspective may be biased, but I like to be proven wrong. Until then, I would rather purchase a durable all metal wear part, than go to the trouble and costs of the extra handling. Whatever your final wear part strategy, it should revolve around having the correct spare parts at the right time at the right location.

Spare parts on stock

References

  1. Elastic collision, Wikipedia
  2. Synthetic applications, W&TS
  3. Hardfacing, Wikipedia
  4. Frequently asked questions about hardfacing, The Fabricator

See also