Pitting corrosion test failure

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Prasu Cutie

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Aug 11, 2016, 2:31:01 AM8/11/16
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Dear experts,

We had pittng corrosion failure in duplex stainless  steel 2205
Process: GTAW
Thk: 7.62mm
Filler: ER2209
Product: pipe
Heat input observed: 1.5 to 2.5kj
Gas: argon 99.9997purity
Weight loss reqd is <4g/sq.mtr, achieved 21g/sq.mtr
Testing is done as per ASTM G48

Can any one tell me why this failure occured, what could be the reason?

Regards
Prasad

nithind...@gmail.com

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Aug 12, 2016, 12:04:29 AM8/12/16
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At what temperature was it carried out..and holding time?

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Prasu Cutie

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Aug 12, 2016, 1:06:53 AM8/12/16
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At 22deg n fr 24hrs


On 12 Aug 2016 7:04 a.m., <nithind...@gmail.com> wrote:
At what temperature was it carried out..and holding time?

Sent from my iPhone

On Aug 11, 2016, at 02:23, Prasu Cutie <pra...@gmail.com> wrote:

Dear experts,

We had pittng corrosion failure in duplex stainless  steel 2205
Process: GTAW
Thk: 7.62mm
Filler: ER2209
Product: pipe
Heat input observed: 1.5 to 2.5kj
Gas: argon 99.9997purity
Weight loss reqd is <4g/sq.mtr, achieved 21g/sq.mtr
Testing is done as per ASTM G48

Can any one tell me why this failure occured, what could be the reason?

Regards
Prasad

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Harish Kannepalli

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Aug 12, 2016, 1:57:26 AM8/12/16
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Hi Prasad,
Most of the tests fail also due to improper sample preparation or wrong dimensions during calculation of weight loss. Ask for a retest for 2 samples.

Regards
Harish.


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nithind...@gmail.com

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Aug 12, 2016, 11:14:27 PM8/12/16
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Hi,
At the below temperature it should pass. Is your end product will be picked and passivated?? If yes, pls do the picking and passivation of test sample, it should pass.

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Perumal Govindan

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Aug 12, 2016, 11:14:45 PM8/12/16
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Hi Prasad

Please let me know the exact material spec and welding consumable brand used for welding.

Further what was the max interpass temp measured, shielding and purging gas used and its flow rates.

Regards
Govindan Perumal

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Mohammed Rafiuddin

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Aug 21, 2016, 6:39:25 AM8/21/16
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Mr.Prasad,

ASTM G48 test is considered to be a check of metallurgical condition of DSS rather than of its performance in any service environment.

We had a similar case.Then client requirements changed and it was asked to perform test according to ASTM A923 Method C which we passed.

Consult your client this may help you.

Regards,
Mohammed 


pgoswami

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Aug 21, 2016, 11:54:27 PM8/21/16
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Mr. Prasad,
 
You've problem with shielding gas selection. For Any DSS or SDSS, Ar+N2(up to 2%) is considered to be beneficial to balance the Ferrite+Austenite Ratio.It's the proven truth.
Typically DSS 2205 should pass the ASTM G-48A test if welded with due care, shielding gas selection etc.
 
Surface preparation etc  may help, however competent Lab personnel would very well know what to do about surface preparation.
 
In the same note did the BM and Filler metal were tested for G48A test.That's important.
 
Hope the above tips would help you.
 
Look forward to your response.
 
Thanks.
 
 

 

Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Engineering Specialist ,

Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

pgos...@quickclic.net

pradip....@gmail.com

 


From: 'Mohammed Rafiuddin' via Materials & Welding [mailto:material...@googlegroups.com]
Sent: Sunday, August 21, 2016 3:33 AM
To: material...@googlegroups.com
Subject: Re: [MW:25273] Pitting corrosion test failure

FAQ_ My duplex or superduplex stainless steel WPQ has failed ASTM G48 testing.pdf

Prasu Cutie

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Aug 23, 2016, 2:25:01 AM8/23/16
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Dear All,

Thank you all fr your great inputs..lot of learning!!

We have re tested according to shell dep fr welding of dss  with another cut piece grom the same pipe with flat specimen(2nos) and ensured proper finishing and avoided sharp edges, proper passivation n pickling. We could get the value of 1.3g/sq.m which was accepted by customer.

Regards
Prasad


On 22 Aug 2016 6:54 a.m., "pgoswami" <pgos...@quickclic.net> wrote:
Mr. Prasad,
 
You've problem with shielding gas selection. For Any DSS or SDSS, Ar+N2(up to 2%) is considered to be beneficial to balance the Ferrite+Austenite Ratio.It's the proven truth.
Typically DSS 2205 should pass the ASTM G-48A test if welded with due care, shielding gas selection etc.
 
Surface preparation etc  may help, however competent Lab personnel would very well know what to do about surface preparation.
 
In the same note did the BM and Filler metal were tested for G48A test.That's important.
 
Hope the above tips would help you.
 
Look forward to your response.
 
Thanks.
 
 

 

Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Engineering Specialist ,

Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

pgos...@quickclic.net

pradip....@gmail.com

 


From: 'Mohammed Rafiuddin' via Materials & Welding [mailto:materials-welding@googlegroups.com]
Sent: Sunday, August 21, 2016 3:33 AM
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