3 replies to this topic

[karthick selvaraj]

Hi,
Can anyone please let me know when we can say that equipment such as Pressure Vessels, Heat Exchanger and Column etc., falls under toxic service such as Wet H2S service, Sour Service and Amine service.


Thanks
Karthick.S

[ankur2061]

karthick,

Without being specific on the exact type of equipment NACE MR-0175 or ISO 5156 - "Petroleum or Natural Gas Industries - Materials for use in H2S-containing environments in oil & gas production - Part 2" provides criteria for selection of carbon and low-alloy steels based on the partial pressure of H2S in the material environment to prevent sulfide stress cracking (SSC)( a type of corrosion phenomena).

The standards says that for partial pressure of H2S in the material environment is expected to be greater than or equal to 0.3 kPa (0.05 psi) than the carbon or low-alloy steels selected for any service (pipe / vessels) shall be SSC-resistant.

Regards,
Ankur.

Edited by ankur2061, 09 August 2012 - 03:35 AM.

[karthick selvaraj]

Hi,

Thanks for your valuable reply.

I am designing a vessel falling under wet H2S service and the customer has recommended we use HIC resistant materials. Also, Self -reinforced nozzles are suggested by the customer.

As per your reply, when the equipment comes under wet H2S service the material shall be resistant to Sufide Stress Cracking - (Acceptable). But why it should also be resistant to Hydrogen Induced Cracking?

Are HIC and Wet H2S meant to be considered separately? Or is it because of Wet H2S that the equipment falls under HIC service?

Also, why are Self -reinforced nozzles suggested by the customer for this service?

Can you please let me know on the above?

Thanks
Karthick.S

[ankur2061]

Karthick,

As the name suggests, H2S environment can also lead to HIC due to liberation of free hydrogen from H2S. For definition of HIC refer the link below:

http://www.cheresour...d-gas-industry/

Regards,
Ankur.