PWHT of Dished ends

[Ravi Shankar]

Hi,

We are in the process of manufacturing pressure vessels confirming to ASME Sec VIII. The plate material used is SA 516 Gr.70. The shell thickness is 10mm ad Dished end thickness is 12mm. Do we need to carry out stress relieving of dished end after forming.

Can somebody guide me?

Regards

C G Ravi Shankar

[Nunu Nuramanu]

Hi Ravi,

If I am not mistaken as long as extreme fibre elongation less than 5% & cold forming is used no stress relieve is required. (I did not do design PV for more than 5 years already)

Please check UCS-79 of ASME VIII Div 1 Code for more details.

Hope this helps you.

Regards,

Nunu

Nunu Nuramanu

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From: Ravi Shankar <cgr...@gmail.com>

Sender: material...@googlegroups.com

Date: Tue, 14 Jun 2011 15:25:27 +0530

To: <material...@googlegroups.com>

ReplyTo: material...@googlegroups.com

Subject: [MW:11328] PWHT of Dished ends

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[murugesan jeyaraman]

When the extreme fiber elongation is exceeded by 5% and any one of the following conditions exist a stress relieve is required: I do not remember exactly i think it is UCS 79 of asme sec viii div 1

1) The vessel will contain lethal substances either liquid or gaseous

2) Material requires impact testing

 

3) The thickness of the part before cold forming exceed 5/8".

 

4) The reduction by cold forming from the as-rolled thickness is more than 10% at any location where the extreme fiber elongation exceeds 5%( can not have a min. thickness less than 10% of the nominal thickness to avoid stress relieving if the fiber elongation exceeds 5%)

 

5) The temperature of the material during forming is in the range of 250 Deg F to 900 Deg F.

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[Ramprasad Chari]

You may go through UCS79 of ASME Section VIII Div 1.Also check tender requirements.Engineers India Ltd, as a standard practice,specifies stress relieving fot thicknesses upto 16mm and Normalising for thicknesses 18mm and above.

Regards

Aarpee

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

Dear Mr. Ravi Shankar

 Stress Reliving  of  formed parts is carried ( eg.Dihsed ends) to reduce the stresse developed duirng forming operation / welding.  The applicability of Stress Relieving is based on the following conditions.

1.0 Process Conditions ( eg. Amine services, sour services -)
2.0 Code Requirements ( Refer UCS -79, for your case)
3.0 Project Specifications.

Process conditions will take precedence, evenif expemetd from code requirements.

Check design basis and document precendece order for  applicable documents. Normally, project specifications will take precedence over code requirements.

With Best Regards,

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


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[Aniket Gupta]

hi dear

sometimes you need to meet the requirement of client also , check with your client specification. 

On Tue, Jun 14, 2011 at 3:25 PM, Ravi Shankar <cgr...@gmail.com> wrote:

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[lassaad mokrani]

Yes Mr.Ravi,

Since cold induces strain (up to 5 per cent) resulting in more hardness. So HT is required.

If you vessel design consider NACE MR 0175 as well, then you have to respect:

*Being in annealed/quenched state

*Hardness limits shall be less than 22HRC

 

2011/6/14 Ravi Shankar <cgr...@gmail.com>

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[amje]

when percentage fiber elongation is more than 5% which heat treatment (normalising or stress relieving) is to be carried out for CARBON STEEL?

whether thickness is criteria?

 

As per EIL specs,normalising is required if thickness is more than 16 mm

[Amit Mavai]

Dear Ravi Shankar,

  If we talk as per code requirement than in sec-VIII Div -1 it is mentioned that if the fiber elongation of formed head if greater than 5% then SR is required & generally below 14mm thk plate fiber elongation comes below 5%.

And if left code than it is client requirement.

Thanks & Regards

Amit Mavi.

Sr. Engineer QA/QA & Welding Technologist

Multimax Engineering Works (P) Ltd.

A6 Industrial Estate Partapur Meerut (U.P)

+91-95481444161