[MW:1849] Re: Query on SMAW electrode selection for API 5L X65

Dear all,

The root pass is grinded to te half (aprx) before make the hot pass. the efectiva area is fullfilled with hot+filler passes, then the final strenght of joint doesn't depend on root pass.

Regarding metallurgical issues I agree and give thanks to Mr. Babu for the explanation.

One more factor is the operative difficult of make the root pass with 7010 or 8010.

BR

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Date: Mon, 30 Mar 2009 22:19:46 +0800
Subject: [MW:1847] Re: Query on SMAW electrode selection for API 5L X65
From: kbabupsg@gmail.com
To: materials-welding@googlegroups.com

Hi,

 

The strength of joint not purely depend on the root pass.

 

My explanation as follows, 

 

1) Main problem starts at Root  if you have the different metallurgical phases at the root, , say you have 50% ferrite and 50% pearlite, the properties of metallurgical phases are different. Obviously that would carry forward to mechanical properties too.

 

2) As we all ,know the corrosion starts, where ever you have two differrent phases or chemical composition ; So in order to avoid this variation , it is necessary to keep the dilution level to minimum in the root pass

 

3) It is well proved by the researchers that, dilution is more on the root pass.

 

4) The strength of weld, not purely depend on the Root passes.

 

 

Thanks & regards,

 

 

K.Babu

Singapore

 

 

On Sun, Mar 22, 2009 at 9:43 PM, ARI <ariv2k@gmail.com> wrote:

Hi,

 

Using E6010-G would keep the dilution level as minimum, but at the same time, it wouldn;t give the UTS equal to Parent metal UTS for API5L X65?

Regards,

 

Ari

 

On 3/21/09, babu k <kbabupsg@gmail.com> wrote:

Hi,

 

Put it in simple words, the use of E6010-G is to keep the dilution level to be minimum ; 

 

Thanks & Regards,

 

K.Babu

Singapore

 

 

On Thu, Mar 19, 2009 at 6:15 PM, Ari <ariv2k@gmail.com> wrote:

Dear All,

Can you please advise, why E6010-G (root) & E-7010-P1 (hot/fill) are
used for Oil pipelines(Sour) containing parent material of API 5L X65.
Since these type of PQR/WPS are being approved by most of the
Company.

As, X65 has an YS of 65,000 Psi, whilst the electrodes used E6010 has
YS of  48,000 Psi, and E-7010-P1 has YS of 60,000 psi. By using both
of these electrodes the weld metal strength would not exceed  YS
60,000 psi.

How its acceptable to keep the low weld metal strength(<YS 60,000 Psi)
than the parent metal (= YS 65,000Psi).

Thy suppose to use E8010 for root and E8018 for hot/fill, for API 5L
X65 materials, which only would give the equivalent WM strength.

As we all know that overmatching weld metal strength causes gross
section yielding in the pipe, whereas Undermatching weld metal
strength will cause straining of the weld.

Your advise/suggession, based on experience is appreciated.

Regards,

Ari

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