HEAT EXCHANGER MATERIAL ss304

[ysc295]

Dear friends,

For one of S&T heat exchanger (AET type) found leak due to Sour water corrosion. The sour water contains Sulfides, Ammonia and caustic which are creating corrosive environment. However the material of construction of the existing condenser cooler is carbon steel so please advise me 304 SS material is more suitable for this application?

Design temp: 81 Deg C shell side and 76 tube side
Design pressure: 8.6 barg/FV for shell side and 10 BARG /FV for tube side.
service ; SOUR WATER for shell side and COOLING WATER at tube side

Thank you,

regards,
Sameer

 

[MFJewell]

Carbon steel is better for heat transfer. The exchanger will need to be physically larger to get the same throughput as before.

 

[weldstan]

Is corrosion on the shell or on the OD surface of the tubes or both?

 

[metengr]

304L is inadequate for sour water service. You would be looking at 316L as a minimum, or duplex grades of stainless steel.

 

[SnTMan]

Leak where?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[ysc295]

Dear,

Corrosion is noticed on tubes as well as on shell and this heat exchanger is not in service now since from one year.

 

[wagga]

You need to consult the material specialist for the appropriate material for the tubes.
My Amine (sour) service HE uses ASTM249-304L. Seems okay for our process.

For the shell, I think CS with the appropriate coating would do the job. We uses AS1548 but with 409 overlay on one of the nozzles and the connected shell area to overcome aggressive SCC.

I heard there is a grade of Belzona paint coating which is good for sour service.

 

[MJCronin]

I believe that if you are going to all of the expense of a premium material upgrade for this HX, you may want to completely replace it.

If you do replace it, I suggest that you consider placing the sour water on the tubeside and the cooling water on the shellside.

Also I would consider using a plate-frame HX for this duty, if the operating pressures were not too extreme.

Corrosive stream is usually placed on the tubeside

MJCronin
Sr. Process Engineer

 

[EdStainless]

Usually when moving to SS construction the tube walls are thinner than for CS (no corrosion allowance) and in most cases this means that total flow is higher (less restriction). The net result is usually less than a 3% shift on total heat transfer capacity.
But you have a lot of other questions to answer before you get to that point in the process.
Are there any chlorides in the water?
What is max temp and min pH?

A lot of people are using 2205 as a default material option.
If you go that way make sure that you do design calcs and use the minimum wall required.

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P.E. Metallurgy, Plymouth Tube