Protection of materials against SSC and HIC corrosion

[nargan2356]

Dear All,

I would like to know a criteria in which materials shall be protected against both SSC and HIC types of corrosion related to H2S.

As far as I know, many factors such as PH, H2S partial pressure can control the criticallity of the SSC and HIC corrosion types. However, I do not have exact information or criteria on that.

Please help me to find a solution for my problem.

Thank you in advance for your kind attention.

Regards,

Karan Sotoodeh

 

[strider6]

nargan

the approach to select materials in environments with H2S is covered by standard NACE MR 0175 / ISO 15156.
this standard define the safe limits, in terms of partial pressure of H2S, chloride content, temperature , material supply... for materials to be used in what is defined as "Sour Service". A sour service is a service with a partial pressure of H2S above 3 mbar and a free water phase.
HIC is covered by the same standard and is controlled mainly by selecting steel with low sulphur (the limits in detailed in the standard)
the standard is divided into:
15156 1 is an introduction
15156 2 is related to carbon steel and low alloy steel
15156 3 is related to CRA alloys (corrosion resistant alloys) like stainless steel, nickel alloys...
and you can buy the standard from NACE

http://www.nace.org/content.cfm?parentid=1108&currentID=1110

A Guide on the Use of International Standard NACE MR0175/ISO15156

http://www.capp.ca/raw.asp?x=1&dt=PDF&dn=109839

corrosion prevention Oil & Gas

hope this help

S.

Corrosion Prevention & Corrosion Control

 

[nargan2356]

Dear madam / Sir,

I am completely awared of the NACE standards in general. Let me describe my question more specific for you:

As far as I know, SSC qualification of a material is mainly dependent on PH value as well as H2S partial pressure.

For more information, If partial pressure of H2S is less than 0.05 psi (0.3 KPA) the service is known as sweet. Therefore, there is no need to consider NACE consideration such as SSC and HIC for that.

On the contrary, higher value of H2S partial pressure (more than 0.05psi) shift the service to sour conditions and three distinct SSC considerations namely region 1,2 &3. The explaination of each region is defined as follows:

SSC Region 1 = Mild Sour Service
SSC Region 2 = Intermediate Sour Service
SSC Region 3 = Severe Sour Service

Although I am not sure about HIC considerations and requirements right, ''HIC consederation may be chosen for only SSC Region 3 = Severe Sour Service.''

I want to make sure of the aformentioned statement ''HIC consederation may be chosen for only SSC Region 3 = Severe Sour Service.''

Thus, I need your assistance to give me some information about this issue.

I am looking forward to hearing from you.

Kind Regards,

T. Nejeh

 

[SJones]

For the definition of sour service, i.e. not sweet, refer to ISO 15156-1, subclause 3.19. For the amount of H2S that may cause HIC, refer to ISO 15156-2,clause 8, paragraph 1 noting the use of the phrase 'trace amounts of H2S'.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[gr2vessels]

nargan,
Read carefully the NACE TM-0284 in order to understand the mechanism of H2S acting on metallic surfaces. The excerpt below introduces you to this concept:
"Foreword
Absorption of hydrogen generated by corrosion of steel in a wet hydrogen sulfide (H2S) environment can have several effects that depend on the properties of the steel, the
characteristics of the environment, and other variables."

Also, "...HIC is related to hydrogen blistering, which has been recognized since the 1940s as a problem in vessels handling sour products."

Hope this helps,
gr2vessels