17 replies to this topic

[Naseem.ahmed48]

Dears

 

What are the main causes for corrosion in plate heat exchangers even if cooling water is chemically treated..

[thorium90]

For one, the other side is not cooling water...

 

This might be a nice read.

http://books.google....ved=0CE8Q6AEwBQ

Edited by thorium90, 25 February 2013 - 11:42 AM.

[Chris Haslego]

Check chloride levels. When pressed / stressed, stainless steel becomes more sensitive to chloride pitting.

[breizh]

Ahmed,

I've observed corrosion in stagnant area between the plate and the gasket . 

 

Breizh

[Naseem.ahmed48]

Breizh

 

Sir your observation is quite well, yes corrosion in stagnant area between the plate and the gasket where the temperature is high...but here we have plate heat exchanger to control the temperature in molasses fermentation not more than 35, as well as i observed pitting starts on the top of grooves (ziz zag) where two plate are in contact each other.....later on pitting converts into the pinholes 

[Naseem.ahmed48]

Thorium

 

 

 

Igot the link reply as .....

 

You have either reached a page that is unavailable for viewing or reached your viewing limit for this book.

[thorium90]

Its more of a preview for the book so not all the pages are available... You could buy or borrow the book...

[isbarqi]

Dears

 

What are the main causes for corrosion in plate heat exchangers even if cooling water is chemically treated..

 

Ahmed,

 

even chemically treated, scale and corrosion still possible to be occurred, I guess no constant 100% pure water on the system. that why, an equipment, such as plate heat exchangers, also need to be cleaned at least once a year.

 

kindly if you can show me what is the product of your HE? one side is water, and what is another side? and on which side the corrosion occured? what kind of corrosion it is? something rusty or like scale stuff?

 

thank you

[Naseem.ahmed48]

Dear isbarqi

 

 

here we have plate heat exchanger to control the temperature in molasses fermentation not more than 35, as well as i observed pitting starts on the top of grooves (ziz zag) where two plate are in contact each other.....later on pitting converts into the pinholes mostly pitting occured in mash side but water side also not too safe....almost after 45 days washing cycle proceed. 
 

Spec of PHE

Description                              SIDE 1                      SIDE 2

 

Medium                                      C.Water                     Either Fermented Mash or diluted molasses                                                     

TEST PRESSURE                       6.7 at                        6.7 at

DESIGN PRESSURE                  5.1 at                        5.1 at

MAX TEMPERATURE                 35 °C                        35 °C

MIN TEMPERATURE                  0 °C                          0 °C

GASKET                                    EPDMP CLIP-ON

PLATE MATERIAL                      ALLOY 316

PLATE THICKNESS                    0.50 mm

HEAT LOAD                               427 Mcal/h

 

 

 

Naseem AHmed

[breizh]

Naseem,

 

What is the metallurgy (alloy 316) ? 

What about the quality of the water ? CL- 

 

Thanks for your feedback 

 

Breizh

[isbarqi]

Well,, I'm not very experienced with molasses or with alcohol plant. but since you found much pitting on mash side, you'd better to check the mineral/anions content of that side. since some anions, like Chlorides, fluorides, or iodides stimulate pitting corrosion. see http://en.wikipedia....tting_corrosion. 

[Atttyub194]

Dear  All

 

Can you share pictures with following info

 

1. Any corrossion product found and whether it was analyzed or not
2. What type of Biocide you are using and whether you have ever observed MIC in your exchangers at your plant
3. What type of cooling water treatment you are using Phosphate based or Cromate based ?
4. What is the velocity of CW and what is the cooling water outlet temperature ?

Best regards

Once In got

[Naseem.ahmed48]

Dear Breizh

 

 

What is the metallurgy (alloy 316) ? it is stainless steel 316

 

What about the quality of the water ? CL-  could't check clorine level , but TDS < 500 ppm and pH = 7.5 to 8.0

[breizh]

Thanks Naseem ,

Let you investigate the CL- content , most probably too high . Let you request support from the company which is doing the Cooling water treatment or Boiler treatment in your facility .

 

Breizh

[Atttyub194]

Dear All

 

Good day!

 

1. Further to the discussions, advise can only be made after looking at the pictures of failure , process data sheet of the exchanger and checking
2. However, NACE paper # 97522  regarding " CORROSION FAILURES IN PLATE HEAT EXCHANGERS" gives a very good guide lines for such failure with few examples of case histories. You may download it free by simply registering at NACE official site

Best regards and God Bless You

 

Ahmed Attyub

[breizh]

http://www.ssina.com..._corrosion.html

 

An other document to support your study

Breizh

[Naseem.ahmed48]

Ahmed Attyub

 

Dear sir

 

1. 
   
2. Any corrossion product found and whether it was analyzed or not.....always little scaling found when these are open for cleaning (always pinhole found where scale with low quantity....on top of grooves of plate.....and never any analysis done.
3. 
   
4. What type of Biocide you are using and whether you have ever observed MIC in your exchangers at your plant (it os suggested by water treatment consultants (i cant confirm u b/c ehcicals we are using having code names....)
5. 
   
6. What type of cooling water treatment you are using Phosphate based or Cromate based ?
7. 
   
8. What is the velocity of CW and what is the cooling water outlet temperature ? outlet temperature 35 C max

[ROHIT_DWIVEDI]

What are the main causes for pinhole in Titanium plate heat ex-changer and other probable cause of leakage having sea water as cooling media and D.M. water as other media ???.......

Flowrate - 1100 m3/hr..Pr...3 Kg.....Temp....50 C...35 C.....D.M. water side

Flowrate - 1292 m3/hr...Pr...2 kg....temp......32 C....34 C....Sea water side