Bls: [MW:16296] Sweet Service Material

Hi Purav Desai,

 

Please find attached table for chemical composition as per owner spec. I was discussed with owner team in technical clarification and said  if Cr is a component that remarkably improves the stress corrosion cracking resistance. However, a content of Cr below 20% fails to provide a sufficient effect. On the other hand, a content of Cr in excess of 30% might cause stress corrosion cracking involving grain boundary breakage. In view of this, the content of Cr is set from 20 to 30%. Preferably it is set from 23 to 28%. But unfortunately owner refuse our technically and they require us to follow their spec. Please give your opinion. Thanks 

Regards,

Lukman

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Dari: Purav Desai <puravdesai1@gmail.com>
Kepada: materials-welding@googlegroups.com
Dikirim: Jumat, 21 Desember 2012 15:49
Judul: Re: [MW:16291] Sweet Service Material

Hi,

 

As far as i experienced, Owner always restricts carbon content and not the chromium content. The number explained by you 0.2% is most common for carbon content. Higher the chromium content it is good because chromium provides corrosion resistance and strength.

 

So i request you to check again with Owner, i think in your case there is a typing error. and if possible send me the owner spec which specifies this requirement.

Regards;

 

Purav Desai.

 

 

On Fri, Dec 21, 2012 at 11:05 AM, lukman hakim <lukman_hakim1981@yahoo.com> wrote:

Hi Puray Desai,

 

Thanks a lot for your explanation. Now I'm handle project which client require us to provide material linepipe for sweet service with Cr content max 0.20%. As per API 5L Forty-Fourth Edition state that Chemical composition for Cr shall be max 0.50%. The problem is our principal difficult to comply and Client require us to provide any technical justification. Can you advice why Client require linepipe material with Cr content max 0.20%? Is there any related with corrosion resistant? Any Code / Std which he follow? Thanks

 

Regards,

 

 

Lukman

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Dari: Purav Desai <puravdesai1@gmail.com>
Kepada: materials-welding@googlegroups.com
Dikirim: Kamis, 20 Desember 2012 16:05
Judul: Re: [MW:16279] Sweet Service Material

When I say Sweet service for gas or oil means that there are no sulfur compounds (H2S) in the gas/oil.

 

For example, when we extract gas from well, the first units would be desalination, dehydration and then sweetening. Desalination unit will remove salts. Dehydration (Glycol type) will remove water particles and Sweetening unit will remove Sulfides from Gas using mostly amine.

 

Hence material selection for sweet service shall be done based on other corrosive elements in the gas/oil like amine, salts etc.

 

I think it does not need to follow NACE requirements.

Please correct me if i am wrong.

 

Regards;

 

Purav Desai.

 

 

On Thu, Dec 20, 2012 at 5:22 PM, lukman hakim <lukman_hakim1981@yahoo.com> wrote:

Dear All,

 

Like you all know that for sour service there are NACE MR-0175 that will determine the requirement for approved material. Is there any similar kind of NACE standard/requirement or else for sweet service? Can you determine the max of Cr content on carbon steel material for sweet service? 

Thanks in advance for any comment..

 

 

Best Regards,

 

 

Lukman

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Regards;

Purav DESAI

puravdesai1@gmail.com

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Regards;

Purav DESAI

puravdesai1@gmail.com

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