In regards to your question about sour service........It has been
determined that hard spots in materials (HAZ and welds) are
susceptible or may lead to cracking in different types of corrosive
service and the hardness limits and recommendations are defined in
NACE MR0175 and NACE MR0103/SP0472. I am assuming you will be dealing
with a carbon steel for the pipe. The lower the CE, the better the
chances of meeting the hardness requirments in the HAZ especially if
you are welding without a post weld heat treatment. Since you are
welding pipe and most likely will not do a stress relief, a CE=0.38 or
less will give you the best chance to meet the hardness limits in the
HAZ. You will still need to qualify a welding procedure to
demonstrate that you can meet the hardness limits if you are welding
to NACE MR0175, NACE MR0103. This is just the tip of the iceberg!
On Apr 28, 4:48 am, tamer said <tamer_ba...@yahoo.com> wrote:
> Dear Mr. Rupesh A. Jambhale
> Thanks for your answer first of all.
> now I am working in project which its material specification spicify that max. CE shall not exceed .38% becasue this for soure service, so , what is the relation between CE and soure service pipeline.
> Best regards
> --- On Wed, 4/28/10, Jambhale, Rupesh A <Rupesh.Jambh...@mottmac-india.com> wrote:
>
> From: Jambhale, Rupesh A <Rupesh.Jambh...@mottmac-india.com>
> Subject: RE: [MW:4977] Carbone Equ.
> To: "materials-welding@googlegroups.com" <materials-welding@googlegroups.com>
> Date: Wednesday, April 28, 2010, 10:30 AM
>
> Dear Tamer,
>
> Carbon equivalents (CE) seek to account for the sum of the effects of the several elements present in steel on its hardenability, and thus the susceptibility of a weld to cracking. It calculates the steel's potential to form martensite or strengthening carbides based upon the steel chemistry. The higher the carbon equivalent, the harder the steel becomes and more prone to cracking upon cooling. Steels with carbon equivalents (CE) less than 0.4 percent are typically easy to weld and welded without special welding methods.
>
> Different codes/ Standards/ literature specify different formulae for calculating CE. Most widely followed is AWS D1.1 which is as follows
>
> CE = C + (Mn + Si)/6 + (Cr + Mo + V)/5 + (Ni+Cu)/15
>
> However, Hardnability can be also controlled by pre-heating and thereby reducing the cooling rate and preventing the formation of martensite
>
> Regards,
> Rupesh A. Jambhale
> Inspection Department,
> Oil, Gas & Petrochemical Division,
> Mott MacDonalds Consultants ( I) Pvt Ltd., Mumbai
>
>
>
> -----Original Message-----
> From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of tamer said
> Sent: 28 April 2010 13:53
> To: materials-welding@googlegroups.com
> Subject: [MW:4974] Carbone Equ.
>
> Why CE calcuations is essential ???
> is it for corrosin or weldiability.
> thx
>
>
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