[MW:12476] Requirement of Solution Annealing for SS DIshed head after forming

Hi Mr Azmi,

 

In addition to the excellent explanations provided by Mr Rana, I would like to add a few more  points.

 

Austenitic stainless steels are very well known for stress corrosion cracking in certain types of operating medias. Sour service  have  two guiding  documents for up stream and downstream industries(see below), where the emphasis is primarily on avoiding " sulfide stress cracking". Sour media could include significant level of chlorides, which   harms austenitic stainless steels significantly 

 

 MR 0175/ISO-15156 Table-A.2 have environmental and material limitations for Austenitic S.S 316L (UNS S31603) as follows:-

• Maximum recommended temperature -149 deg C
• Partial pressure H2S Max-1.5 psi
• Max chloride concentration -1000 ppm.

In addition these materials shall also

• be in the solution-annealed and quenched, or annealed and thermally stabilized heat-treatment condition;
• be free of cold work intended to enhance their mechanical properties; and
• have a maximum hardness of 22 HRC

The requirements of the other document, NACE MR -0103, to prevent SSC (Sulphide stress cracking) in wet H2S environment:-

• Austenitic stainless steels that meet the chemical composition requirements specified in Paragraph 2.5.2 are acceptable at a hardness of 22 HRC maximum in the solution-annealed and quenched or solution-annealed and thermally stabilized condition, provided they are free of cold work intended to enhance their mechanical properties.

As you can see from above , both NACE documents talk about the similar requirements

Forming of heads ( cold  or hot ) is  very well known to all  increase the mechanical properties of austenitic stainless steels including hardness and induce residual tensile stress. Any increase in hardness value and residual tensile stress due to forming  accelerates SCC significantly.

As these forming strains can not be removed by any form stress relieving between 450-650 Deg C( sensitization range), austenitic S.S have no choice but to be fully solution annealed or subjected to thermal stabilization anneal.

Hence from designers stand point  solution anneal is considered to be a "safe approach rather then being sorry".  ASME SecVIII, DIV-1 does not readily call for solution anneal of  austenitic stainless steels  in all conditions except that there are something written in fine prints in UHA-6  & UHA-105 which directs to solution annealing to ensure the best properties of this alloy.

Thanks.

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of jignesh.rana@Linde-LE.com
Sent: Wednesday, September 14, 2011 3:07 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:12449] Requirement of Solution Annealing for SS DIshed head after forming

Dear Mr. Asad,

I like to share my views on the topic with respect to the various applicable code.

1.0 ASME Section VIII  Div. 1 -    Since the material is SA 240 316L,(and assumed that is being cold worked)  , requirements of post fabrication heat treatment due to straining as per
       UHA- 44 will not be applicable and therefore  solution annealing is not required. Please note that any of- L Grades" is  not included in table UHA- 44.

2.0  Considering Sour Services-----

       NACE MR 0103 - Austenitic stainless steel shall be supplied with 22 HRC hardness max. in solution annealed and quenched or sol. annealed and thermally stabilized conditions.
       As per this clause thermal treatment is not required (if  fiber elongation exceeds 5 %), which is case for carbon and low alloy steel as per clause no. 2.1.7 of NACE MR 0103.

However, considering good practice, ensure hardness of formed dished end below 22 HRC.

With Best Regards,

Jignesh R Rana
Manager - Materials Technology, QA/QC & Standards

Linde Engineering India Pvt. Ltd.
'Linde House'
Opp: VUDA Office, VIP Road, Karelibaug,Vadodara - 390018, India.
Tel.: +91 265 3056789, Fax: +91 265 2335213 , Mobile:  +91 90999 86019
jignesh.rana@linde-le.com, www.linde-india.com

This e-mail is confidential. If you are not the intended recipient, please notify us immediately. You should not disclose its contents to any other person nor use it for any purposes.






From:        asad azmi <azmiasadayub@gmail.com>
To:        materials-welding@googlegroups.com
Date:        13-09-11 16:55
Subject:        [MW:12442] Requirement of Solution Annealing for SS DIshed head after forming
Sent by:        materials-welding@googlegroups.com

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Dear All,
 
Greetings.
 
SS Vessel is being fabricated as per construction code - ASME SEC VIII DIV 1
 
SERVICE : SOUR Service
 
Material of Construction  for Dished Head - SA 240 316L, 20 mm Thickness.
 
I  believe stresses will be  induced in the material  during forming and as a result , Sulfide Stress Cracking (SSC) failure may occur during operation.
 
Whether Solution Annealing of SS Dished Head is required after forming?
 
Please give reference of any International Standard.
 
Thanks & Regards
 
Asad Azmi

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