5 replies to this topic

[Cwsrt]

Hi good morning.

 

We are currently employing a thermal desalination technology for our treated water needs.

 

Pipings of our distillate product and all downstream pipings are of killed carbon steel (KCS) material. Since our operation, we noticed high iron content of our product water. This lead to the idea of corrosiveness of the desalinated water.

 

Initially we suspect dissolved gases as the main reason for the high corrosion rate. However, were unable to identify other root causes.

 

Aside from the dissolved gases, does the purity of water (conductivity ~5 uS/cm) also cause corrosion?

 

Please help me out.

 

Thank you.

 

Regards,

Cwsrt

[Dazzler]

This is something you will need to research.   Water in various forms of impurity/purity can be corrosive.  

 

The article link below indicates: "Desalinated water is considered corrosive due to its inherently low mineral content and is not suitable for consumption without post treatment".

 

http://www.waterrf.o...ive_Summary.pdf

 

A different steel than KCS is most likely needed.

 

Dazzler

[markymaark]

Yes, a highly pure distilled water is extremely corrosive and will suck out the iron of all carbon steel.  You should change your distillate piping to either a sanitary plastic piping or 316 SS

[Rahimzadeh]

Dcwsrt:

Desalinated water PH normally is lower than 6.0 , in this regards this water will be nuetralized with sodic phosphate before distribute to user.

In additon the mulfunction of start up ejector (for removing co2) the water become acidic, please checkand tell us the PH of your distillate water.

 

BEST FOR YOU

M.R.Rahimzadeh

[Cwsrt]

Hi M.R. Rahimzadeh,

 

The start up ejector seems to be working just fine. From our routine sampling ang testing, pH of the desalinated water ranges from 5.0 to 9.0.

 

 

What corrosion mechanism governs when "pure" water (low mineral contents) is corrosive?

[Rahimzadeh]

 Dear:

Please recheck your desalinated water PH , due presents of bicarbonate in sea water ,this ion decompose co2 will release and therefore the PH of water will be reduce.

Best Regards

M.R.Rahimzadeh