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[iceman53y]

Hi!

 

I am trying to select the Pipeline and vessel material for a project with 1800PPM H2S and with CO2 Content 1.7 mol%

This is for a compressor package therefore the Pressures will vary across the process.

I've done the following calculations:

Case-1 (Suction): Partial Pressure of H2S @ 95 psig Pressure = 1.36 kPa
Case-2 (Interstage): Partial Pressure pf H2S @ 235 psig Pressure = 3.06 kPa
Case-3 (Discharge): Partial Pressure pf H2S @ 410 psig Pressure = 5.27 kPa

 

All three cases seem to fall under SSC region-2 of NACE MR0175 section 7.2.1.2

 

Case-1 (Suction): Partial Pressure of (H2S + CO2) @ 95 psig Pressure = 14.22 kPa
Case-2 (Interstage): Partial Pressure pf (H2S + CO2) @ 235 psig Pressure = 32.37 kPa
Case-3 (Discharge): Partial Pressure pf (H2S + CO2) @ 410 psig Pressure = 55.05 kPa

I've also calculated the pH values for each case using the Annexure D on NACE MR0175:

pH Case-1: 4.5  
pH Case-2: 4.5
pH Case-3: 4.5

We usually use the widely used A106 grB as the piping material and SA516gr70 when we are dealing with sweet gas.

NACE MR0175 recommends using table A-2 for selection of materials that fall under region-2.

 

I'm confused since A106 GrB is also mentioned in Table A-2. I'm not sure what I should select as the piping and vessel material for each of the three cases.

 

Please help!

 

Thanks! 

 

[iceman53y]

Am I missing some information on this?

 

No one seems to be replying on this topic.

 

Ambient conditions: 50 degrees C.

Location: Middle East.

Dry, Desert and Arid Conditions.

 

Approx life of this compressor package is 10-15 years.