Re: [MW:12505] mixed feed convection coils

Dear Karandish,

Considering the kind of crack and the type of connection, one of the reason for the failure could be low cycle thermal fatigue & bending stress.Please remember Austenitic stainless steel will have higher thermal coefficient of expansion. I dont think it has happened "only" because of metallurgical degradation.

Was this failure happened after any thermal shock due to abnormal operating condition like emergency shutdown?

what about stress analysis report for those coils? Sufficient flexibility was there and stress induced were with in the allowable stress limit?

On Sat, Sep 17, 2011 at 9:08 AM, AA karandish <aa.karandish@yahoo.com> wrote:

Dear Vanchi,

I had made a typewriting error the correct material is A312 TP 347H, welding is performed at vendor shop (not at site) I am searching in the vendor documents, and will inform you more detail about welding consumable, treatment ,...

Regards,

Karandish

From: Vanchinath S.A. <vanchinaths@gmail.com>
To: materials-welding@googlegroups.com
Sent: Friday, 16 September 2011 9:59 AM
Subject: Re: [MW:12463] mixed feed convection coils

Dear Karandish,

Is the material 304H or 347H. I presume it should be 347H. Did you carryout any stabilisation treatment upon completion of weld? what is the metal temperature and what consumable was used for weld?

regards

vanchi

On Thu, Sep 15, 2011 at 3:15 PM, AA karandish <aa.karandish@yahoo.com> wrote:

Dear experts,

In attached images you will find the failure happened on the junctions of header to heater tubes of a natural gas + steam heater. The heater specification is as follows:

Inside fluid: natural gas + steam

Outside fluid : flue gas from burning of natural gas in the reformer of an Ammonia plant.

Tube and header material : SA-312 TP 3047H

Considering the above let me have your suggestion regarding the failure reasoning.

Regards,

Karandish

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With Regards,

Sudharsan

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