Requirement of Solution Annealing for SS DIshed head after forming

[asad azmi]

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

[Karthik]

Hi, Pls.refer Sec.VIII,Div.1 - UHA 44 and Table UHA-44. You should calculate the strain % as per UHA44 and if  you cannot calculate,then UHA44(b) shall be applied and follow as below. According to Table UHA-44,If strain Percentage exceed 20% (for Design Temp - 580 to 675) and 10% for design temp. more than 675 degree celsius ,Head shall be heat treated (heating at the temperatures given in Table UHA-44 for 20 min/in. (20 min/25 mm) of thickness or 10 min, whichever is greater, followed by rapid cooling:)   Pls. find below the extraction. UHA-44 REQUIREMENTS FOR POSTFABRICATION HEAT TREATMENT DUE TO STRAINING UHA-44(a) The following rules shall apply in addition to general rules for forming given in UHA-40. UHA-44(a)(1) If the following conditions prevail, the cold formed areas of pressure-retaining components manufactured of austenitic alloys shall be solution annealed by heating at the temperatures given in Table UHA-44 for 20 min/in. (20 min/25 mm) of thickness or 10 min, whichever is greater, followed by rapid cooling: (a) the finishing-forming temperature is below the minimum heat-treating temperature given in Table UHA- 44; and (b) the design metal temperature and the forming strains exceed the limits shown in Table UHA-44. UHA-44(a)(2) Forming strains shall be calculated as follows:   (b) spherical or dished heads formed from plate: % strain = 75t/Rf(1-Rf/Ro) R f p mean radius after forming R o p original radius (equal to infinity for a flat plate) p nominal thickness of the plate, pipe, or tube before forming   UHA-44(b) When forming strains cannot be calculated as shown in (a) above, the Manufacturer shall have the responsibility to determine the maximum forming strain. In such instances, the forming limits for flares, swages, or upsets in Table UHA-44 shall apply.     Thanks & Regards,. (Karthik) Karthikeyan.S QA/QC Manager Getabec Energy Co.,Ltd. 379,Moo6,Soi8,Nikhomphatana, Rayong-21180, Thailand. Phone: 0066 38 897035-8 (Off) Fax: 0066 38 897034 Hand Phone: 0066 892512282 --- On Tue, 9/13/11, asad azmi <azmias...@gmail.com> wrote:

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[jignes...@linde-le.com]

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
jignes...@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 <azmias...@gmail.com>
To:        material...@googlegroups.com
Date:        13-09-11 16:55
Subject:        [MW:12442] Requirement of Solution Annealing for SS DIshed head after forming

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[pgoswami]

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,

pgos...@quickclic.net

 

---

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

[jignes...@linde-le.com]

Dear Mr. Goswami,

Thank you very much for the detailed and informative reply, as usual.  However, I like to share my  views further to this.

The important requirement for Austenitic stainless steel - " shall be free from cold working intended to enhance mechanical properties " requires further discussions.

Can dished end forming be considered as cold working intended to enhance the mechanical property? If so, then even shell rolling also falls in same category.
According to my opinion, Material like  A 666, 1/2 H, 1/4H, 3/4H etc. may fall in this requirement. ( Cold worked austenitic stainless steel materials). Pl share your views.

From practical point of view, during fabrication process (forming, welding and pressure testing etc.) certain amount of residual stresses will develop and it is not possible to make the vessel completely free from residual stresses.  

Hence I understand that, a sealing limit on residual stresses, based on field and laboratory data been suggested for different materials. This sealing limit is in turn reflected as Hardness values for different materials.

Let's consider hypothetical case, dished end with hardness less than 22 HRC - then why to go for Solution Annealing ?

Further, as per ASM Handbook Vol. 4 (Heat treatment of steel),  Austenitic stainless steel may be stress relieved at @ 900 deg C. However, the material, design conditions, fabrication procedure involved etc. needs to be considered before final call. If stress relief is warranted then due regard to metallurgical changes and  effect on remaining life of the equipment shall be considered.

Further, solution annealing (water quenching or fast cooling in other medium) reintroduce high residual stresses. (Ref. ASM hand book vol. 4)
 
Back up supportive are all fine, but when  manufactures / inspector has to take a final call on this, code requirements has to be followed.

As far as the code requirements are concerned neither upstream nor downstream code for sour services clearly indicates- Thermal treatment (solution annealing) is required for austenitic stainless steel material, after cold working. It restrict the residual stresses and in turn the hardness values for austenitic steels. If it exceeds 22 HRC then further decision has to be taken.

Even for carbon and low alloy steel the limit is restricted upto 5 % fiber elongation.  For the hypothetical case of formed end with fiber elongation < 5 % and meeting the hardness requirement, thermal treatment to relieve residual stresses is not required as per specification.

Thanks.

[Krishnnaa26]

Hi mr. Jignesh
I have come across some failure cases of austenitic stainless steel dished ends due to high hardness.
Now the issue is there are some ASS equipment intended to use in h2s service in a petrochemical plant. Few equipment delivered and hardness check on production dished ends revealed > 300BHN. Is it advisable to do stress relieving of the delivered equipment at site at 400ºC for one hour.
Krishnnaa

[george....@gr.bureauveritas.com]

I suggest you have a look on ASME BPVC Section VIII - Div 1 Part UHA and more particularly UHA-44.

best regards

Dr. Georgios Dilintas

Authorized Nuclear Inspector
Authorized Inspector Supervisor
API 510 Inspector

I&F REGIONAL TECHNICAL MANAGER
BUREAU VERITAS HELLAS

Tel: +30 210 40 63 113/4
Fax: +30 210 40 63 118
Cell: +30 69 44 64 62 04
(See attached file: Dilintas_George.vcf)

Krishnnaa26 ---16/01/2014 05:09:44---Hi mr. Jignesh I have come across some failure cases of austenitic stainless steel dished ends due t

From: Krishnnaa26 <krishna....@gmail.com>
To: material...@googlegroups.com
Date: 16/01/2014 05:09
Subject: Re: [MW:19870] Requirement of Solution Annealing for SS DIshed head after forming
Sent by: material...@googlegroups.com

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[VIPUL]

Hi,

Please let me know What is the finishing forming temperature as per UHA-44.

Thanks,

Vipul

[VIPUL]

Hi All,

I have read all the valuable discussion happened here, I come to know about few point what I was not aware thanks all of you.

I have a torispherical dish head with fiber elongation of 6%, Design temperature =200°C, MOC = SA-240 Gr. 316L . As per UHA -44 weather Solution annealing is required.

The point behind asking this question is if the design temperature is below 580°C (as given in Table UHA-44) then do I need to solution annealing.

Second thing As per clause UHA-44 (a) 1 (-a) what is finishing -forming temperature. I believe it is not design temperature.

 
On Tuesday, 13 September 2011 15:48:03 UTC+5:30, asad azmi wrote:

[George Dilintas]

check Table UHA-44.

Factors to consider are:

Alloy Grade

Design Temperature (lower and higher temperature range)

Strain after forming

The combination of the above factors is indicating if HT and at which temperature needs to be performed

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Ph.D in Mechanics of Solids - Computational Mechanics

A.I.S, A.N.I, IRCA Lead Auditor

Welding, Stress Analysis, Corrosion, QA/QC, Failure Analysis, Risk Analysis