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Soil : from benign to carcinogenic Print E-mail
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Corrosion is the cancer of metals

“A pipeline in your backyard”, it could happen to everyone. Though pipelines are a very safe way of transport, indisputably our previous blog on this subject has lead to severable remarks. Some possible examples: “The leakage of pipelines did already lead to contaminated soils” and “Some of these soils now contain carcinogenic compounds”. It can’t be denied that such disasters happen, yet … why did they occur?

As in many cases insufficient maintenance and follow up, in some cases even neglect, are at the origin of a leak. In most cases corrosion is the culprit. When not adequately controlled and managed, corrosion can initiate as a small spot and evolve unbridledly to vast proportions and penetrations. Some types of soil are quite aggressive towards metal pipelines and what happens underneath earth’s surface can not always be seen in a simple manner.

So, what’s “aggressive soil”? First of all it’s important to realise that a large part of soil is composed of ‘water’ and that, like drinking water, groundwater can contain several components that can cause or inhibit corrosion. Water can for example be quite acidic, in which case the water is called ‘aggressive’. Water can also contain chlorides, sulphates and phosphates that – dependent on their concentration – can promote or rather inhibit corrosion. In which degree water can be named aggressive/corrosive is dependent on many parameters. Some examples:

  • The type of soil – sand, clay, peaty soil etc.: the type of soil and the water content are closely related. The water content of sand is for instance relatively low, whereas peaty soil contains lots of water; therefore sand can generally be considered to be less corrosive than peaty soil. Oxygen content is another parameter that’s dependent on the soil type; on its turn the oxygen content is closely related to the corrosiveness of the soil etc.
  • DSC02084Depth: Soil is composed of several layers. As an example it can be mentioned that the top layer of the region “Antwerp Kempen” is mainly composed of sand, whereas in deeper layers also clay can be found. It should also be realised that these ground layers are not necessarily parallel to earth’s surface, yet can evolve quite erratic and/or slant. The underground clay layer at the Antwerp Kempen region surfaces for instance some hundred kilometres to the west. Also human activity such as excavations can influence soil structure. etc.
  • Surface water versus groundwater: Generally spoken groundwater is not only ‘cleaner’ in comparison to surface water, yet it should also be taken into account that the groundwater level is varying with rain volumes. At certain depths the ground water content is fluctuating in function of the weather and the seasons. In some cases the effect of the ground water level can also be very local and temporary, as for instance when a certain area is reclaimed for infrastructural works. etc.
  • The region – rural, industrial and maritime, ...: dependent on the region the soil composition will vary. In maritime environments soil does for instance contain a higher chlorine content, whereas in industrial environment soil can be enriched by sulphates and in rural areas fertilisers can increase the phosphate content etc.
  • Soil is full of life: Independent of the soil type, there’s always a lot of activity. Several types of microorganisms can influence the corrosion behaviour of buried metal structures. Like ourselves, microorganisms need oxygen to survive. As previously mentioned, oxygen plays an important role in the corrosiveness of soils, hence the presence of microorganisms indirectly influences corrosion processes. Not to forget: some microorganisms do not capture oxygen out of their environment, yet by ‘digesting’ sulphates; these microorganisms are called “sulphate reducing bacteria”. The waste of this digestion process acidifies the environment, hence increases its corrosiveness.
  • Stray currents: Current leakage and induction from rail- and tramways can induce electrical currents in metal structures that are buried near to the tracks. As corrosion is an electrochemical process, these stray currents can influence corrosion behaviour.

pijpleidingaanleg_-_trekmechanismeCorrosion of buried metal structures is a very complex phenomenon that can not be explained in one blog. Corrosion protection of buried structures starts already before their burial, i.e. by choosing an appropriate position and, in case of pipelines, of an appropriate trajectory. Passage through peaty soil will f.i. be avoided. Subsequently classic corrosion protection measures are put in place. For pipelines it usually concerns a bitumen or paint layer, complemented by a cathodic protection system. The choice and control of the paint and cathodic protection system are on their turn dependent of the properties of the soils that will be passed etc.

Yet, despite its complexity, pipeline corrosion protection also remains a “common sense” issue: Prevention is better than the cure. A wisely chosen trajectory, a superior coating system and a correctly controlled cathodic protection are minimal requirements. The common sense attitude is and will remain the best way to prevent corrosion, the cancer of metals.

 

Do you want to learn more about corrosion protection of pipelines? Our blog will update you regularly; follow us using RSS or by returning regularly to this website.

 
Fooled with trick candles? Print E-mail
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eeuwige_brandende_kaars“It’s a familiar scene at birthday celebrations: The guest of honor blows out the candles on his or her birthday cake. Thin ribbons of smoke escape from the wicks, signaling the guests to clap and cheer.

But wait! The wicks begin to glow a fiery red. They flicker, and suddenly the flames reappear. Looking bemused, the birthday boy or girl tries to blow out the candles – again and again, much to the delight of the onlookers.”

 

This are the first paragraphs of a recent article in “Chemical and Engineering News".

What are the secrets behind the trick candles? Indeed, a metal is involved.

Yet, as they repeatedly ignite of their own, are they safe?

 

Maybe it’s not the birthday boy or girl that’s fooled, but maybe it’s you !!!

 

Read the full article here, just to be safe.

 
A pipeline in your backyard Print E-mail
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P1010087On some hundred meters of Materials Consult, almost in our backyard, a new pipeline is being constructed, a technological master piece. This underground steel pipeline will provide energy to several thousands of companies and households.

Construction of such a pipeline is executed in several steps, each of utmost importance in order to guarantee a continuous supply. At the same time these steps have to guarantee, individually and as a whole, that the pipeline can be  operated in a safe way, towards the public and  towards the environment. Sustainability is more than only a technologically correct realisation of the project.

In this and subsequent blogs focus will be oriented towards the most important materials aspects related to the construction and preservation of such a pipeline. An overview:

  • The corrosion risks to which steel pipelines are subjected, are in large part determined by the properties of the bottom types through which the pipeline passes.
  • Which steel is to be used to produce the pipeline sections, how are they shaped and given their curvature? Afterwards the pipeline sections are coated as a protection against corrosion.
  • Pipeline sections are assembled by welding on-site, at which moment the welding zone should be protected from rain, wind etc.
  • Welding procedures and the welds themselves are subjected to inspection procedures in order to guarantee the integrity and soundness of all welds.
  • After welding and inspection all welds should be coated as a protection towards corrosion.
  • In order to protect the pipeline from damage while it descends in the slot, the slot is first filled with a backing material. At the same time this backing will uniform
  • the environmental conditions to which the pipeline is subjected.
  • Separate from the coating, additional corrosion protection is guaranteed by means of a so-called ‘cathodic protection’ system.
  • In order to prevent leakages near pump stations, but also in function of corrosion prevention, all connections of the pipeline to pumps, valves etc. should be correctly designed and realised.
  • Once the pipeline is in production, follow-up remains necessary:

A maintenance book is kept up-to-date, not only in terms of maintenance to the pipeline itself, but also when e.g. road works are being performed in the neighbourhood of the pipeline.

When works are being performed in the neighbourhood of the pipeline, the position of the pipeline must be clear to everybody involved and, if necessary, supplementary supervision has to be organised.

The proper functioning of the cathodic protection system has to be verified regularly and adjusted when necessary.

pijpleiding_aanlegThe previous list is certainly not complete. We only want to picture the most important aspects in which materials technology plays an important role to guarantee the integrity of the pipeline. In the upcoming blogs we’ll give more detail as to the previously mentioned points. This way we hope to give you more insight in the construction of large steel pipelines and to show you that the NIMBY-attitude (Not In My BackYard) is certainly not necessary towards pipeline projects.

Materials Consult is fully confident that the pipeline in our backyard is completely safe, thanks to the efforts of many engineers, workers and other personnel; they merit our confidence. The valves can be opened.

 
Retirement of the traffic jams Print E-mail
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fileDaily congestion on Brooklyn bridge, the incredible traffic jams around Paris, an increasing number of trucks on our highways, railway infrastructure that is outdated and ash clouds … getting goods and ourselves at destination in a timely way has never been that difficult. Several alternatives have been proposed: monster trucks, an increased use of water- and railways, obligatory carpooling for people residing permanently at their office, registration and payment of the distance you drive etc. However, there is one solution that never appears in our multimedia world, despite it’s simplicity.

This solution is well known from gas and water transport, yet is also responsible for the transport of chemicals and oil, protection of electrical circuits transporting our multimedia signals, for postal and components distribution in several companies and many millions of people pass through them every day. “The 5th transport modality” is the alternative name for the billions of kilometres of pipelines crossing our world. They’re available in an enormous amount of sizes and materials; steel and polymer pipes for transport of gas, water, chemicals and message cases, concrete for sewer and tunnels or brick vaults, all examples of how pipelines ease our life.

tunnelconstructieThe world should be encouraged to use much more pipelines. In many countries the capabilities of earth’s surface are congested, so there should be no doubt to expand our 2-dimensional traffic vision to a 3-dimensional one. This could be done below or above ground level, yet above ground is a less adequate solution in terms of climate change, our green backyard and our nature in general. Transport systems below ground are in this respect much more reasonable, although the engineering challenges are certainly not less. Evacuation and storage of exhaust gasses, development of electromagnetic transport systems as an alternative to combustion motors, stability and corrosion resistance of underground structures, the geometric exact positioning of drilling and other digging activities, it are only some of the vast range of technical challenges. Pipelines, the 5th transport modality, are however and without any doubt a valuable alternative for the 2-dimensional problems that clearly can not be solved on earth’s surface.

Many technicians, economists and scientists of many disciplines have proven that pipelines are the key to a more sustainable, faster and greener alternative for the present traffic indigestion. In The Netherlands and Belgium the “Buisleiding Industrie Gilde” (Pipeline Industry Guild) groups people that encourage an increased use of pipelines; their representatives participate to all related social, economical and technical discussions. More information can be found on the Dutch website www.bigleidingen.eu.

As to the technical challenges of materials in underground applications, some blogs of the upcoming weeks will be attributed to the pipeline theme. And for those searching a job with perspective … in the pipeline industry there’s clearly a future ahead.

piping_dame

 
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