Alloy 825 application on H2S environment

[Xeros]

Dear all,

Licensor request to apply Alloy 825 on H2S service that H2S partial pressure is more than 900 mbar. (on equipment and piping)

service temperature is about 50 degree C, no chloride and vapor phase (compressor system).

However, I don't know the reason.

Is it caused by corrosion or cracking?

Best regard,

 

[strider6]

CO2 Corrosion?
you should look at the materials selection report or similar document to understand the reason of a material selection.
If the CO2 content is high then it could be that the calculated corrosion rate is too high for a carbon steel and is necessary a corrosion resistant alloy. if there are no chloride and the temp is 50°C then a Stainless Steel could be an alternative selection..

S

Corrosion Prevention & Corrosion Control

 

[Xeros]

Thanks, strider6

The application of alloy 825 could be understanded if chloride is more than 50 ppm and H2s partial pressure is more than 100 kPa as per Table A.2 on NACE Mr0175 ISo 15156.

However, there is no chloride.

therefore, I have asked if there is other reasin for alloy 825 application.

 

[TomEun]

Your opened data is not enough to recognize the reason. Presumably we may consider the following conditions if the material selection is reasonable.

- in ammonium bisulfide environment
- any upset condition with contamination (i.e., chloride, sulfuric acid, phosphoric acid, etc.)
- in case required higher strength and/or erosion resistance

Thomas Eun

 

[Xeros]

to thomas Eun

thanks your concern.

main service is acid gas service. exactly, the amine(MDEA) regenerator OVHD gas.

therefore, i think it is not in ammonium bisulfide environment, no acid solution and no erosion.