Values of corrosion rates for carbon steel in contact with raw seawater

[Mathp]

Dear all,

I am currently looking for defined values of corrosion rates found for carbon steel pipework circulating raw seawater saturated with air. Information concerning carbon steel used as piping/pipe material (different flow velocities (without solid particles at the moment but if you have, it could be interesting as well), pressure, even temperature maybe) and as structure material (immersed, splash, atmospheric zones ...) will be helpful. I would like to compare values from different references to provide "sure" results.

Some values are available in papers but experiments do not often use natural seawater and experimental conditions are usually stagnant.

I tried to look for values in ISO standards but they give trends (not values) in function of variation of parameters.

Thank you in advance for your answers, best regards.

Mathilde Perrier

 

[CoCoE]

Please try in ASM handbook, I believe there are some information. Are you going to use CS for sea water?

 

[cloa]

You do realise that natural seawater varies enormously by location and even collection variation in the same location in its corrosive effects and do you allow for the microbial effect which add to the complexity- that why they prefer artificial sea water keeps the variability down.

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[LittleInch]

Why? CS in contact with warm aerated seawater corrodes at a huge rate and is simply a terrible material to use for aerated seawater. If its bad does it really matter how bad?

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[CoCoE]

0.1mm py is the corrosion rate I could find out (in stagnant condition). There may be formation of calcarious scales as well, which will act as a barrier for further corrosion. Also sea water constituents are almost remain same at all locations, and pH is also quite constant in all seawaters approx 8.2. However, the rate of corrosion will depend on the flow velocity and dissolved Oxygen in the seawater, expectingly very much higher than fresh water. Due to high conductivity, the corrosion rate also gets high. So we may expect a corrosion rate of approx 5-7 times of that of fresh water corrosion.

 

[SJones]

Comparing corrosion rates from circulating seawater in a piping system with structural steel in the three zones is not really a worthwhile exercise, particularly splash and atmospheric zones. This is the second question that you have asked in this respect, and it would be more helpful if you would elaborate further upon what you are actually researching such that we can help you better. If you want to review seawater immersed steel corrosion rates, your best bet is to get hold of the suite of papers by R E Melchers. Here are a couple to get you started:

R E Melchers, Effect Of Immersion Depth On Marine Corrosion Of Mild Steel, Corrosion, Vol 61, (9), 2005, pp 895-906

R E Melchers, R Jeffrey, Influence Of Water Velocity On Marine Immersion Corrosion Of Mild Steel, Corrosion, Vol 60, (1), 2004, pp 84-94

Steve Jones
Corrosion Management Consultant

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[mrfailure]

You should try the Handbook of Corrosion Data published by ASM. This contains lots of data from lots of sources to compare corrosion rates.