Recently, the gas process component

[ENGRANIA]

Recently, the gas process component has large change in some harmful component specially h2s which reaches to 1000 ppm.
Now we want to replace the existing bundle for gas air cooler by new one.
The existing material for the old bundle is
Tubes sa- 214
Tube sheets, plug plates and end platez sa- 516 gr.70
We will change only the material for tubes.
There is two options.
Using Sa-179 HIC Material
Using duplex stainless steel.
P : 1174 psi
T : 275 °F
FLUID Natural gas
In your opinion , what are the best material for tubes suitable for these conditions and keep no change in tubesheet material.

 

[0707]

A179 is edentical to yours anterior sa 214, meanwile A179 has HIC requirements according to nace, so is much better than the previous material. To chose a duplex material you have to think in bennefits versus costs, under certain condiction duplex ss can be an improuvment but in other condictions can be a worst choice you have to ponder your operating condictions and decide accordingly.

Regards

 

[ENGRANIA]

I know that duplex s.steel will be better but Galvanic corrosion can occur where different metals are coupled in a conductive fluid. So i prefer using SA-179 but i have some doubts about its behaviour with wet H2S.

 

[Dhurjati Sen]

Is your unit a standalone one, or are there others? Experience sharing could be useful.

Is this sudden increase in H2S a temporary phenomenon, or is it going to be a permanent feature?

Changing the air cooler metallurgy ONLY, and leaving the associated piping, reflux drum, etc. unchanged is not advised.

Using only two metallurgies for replacement is not advised too.



DHURJATI SEN
Kolkata, India

 

[EdStainless]

How wet is it?
If you haven't seen corrosion (other than from H2S) then why go to a CRA.
Areyou sure that the rest of you steel piping will resist HIC/H2S?

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