[MW:859] Re: 835] Re: Clarification on Heat treatment / PWHT -Reg.

For Cr -Mo steels the most important factor is the tempering temperature of  the procured  materials. If he materials are procured in Normalized & tempered condition, and  if the PWHT temperature as occured is lesser than the TEMPERED temp. of the procured state , then it should pass the mechnaical tests . As suggested by mr.Sachin, PQR needs to be established and  at the same time the parent materials also needs to be tested for tensile, yield in general and  impact test if  the specification of  project vis-a-vis MDMT call so.

Regards,
tagore

On Wed, Jun 11, 2008 at 8:47 AM, Muhammed Ibrahim <ibratech@gmail.com> wrote:

Dear Sachin,

 

Code says about the increase or decrease of time at a temperature. atleast 80 percent of the PQR shall be in production. I am not clear about the time it discuss.

 

2008/6/11 sachin sankhe <sachin.sankhe@rediffmail.com>:

 
Dear Rishi,

Hardness wont be suffucient to accept since we have changed grain structure to certain extent by exceding PWHT temp.resulting in change in mechanical properties.

In that case you need to re-qualify the procedure with new PWHT temperature and all mechanical test to be done as per relevant specification requirement.
If the test passes then we can accept the production joint
If it fails then analysis of failure to be done and results to be conveyed to client.
Based on criticality of the job,let client decide wether to reject or do PHWT gain.
If they propose PWHT again then subsequently we have to qualify procedure with 2 times PWHT.

OTHER MEMBERS ARE ALSO WELCOME TO GIVE THEIR OPINION.

Regards
Sachin.Sankhe


On Wed, 11 Jun 2008 Singh Rishi Raj(Tasnee Site) wrote :

>Dear Friends,
>
>Staying with the subject line of heat treatment, I wanted to know (since
>long ) --------
>
>
>
>What should be done if the temperature while doing PWHT exceeds the
>range mentioned in WPS ??
>
>
>
>For example lets say-
>
>A weld between A335 P11 ( P 4  Gr 1) , thickness 17mm.  WPS ( & B 31.3
>) has the PWHT temp as 704-746 deg C.
>
>If the temp of  PWHT cycle exceeds the higher value by 40deg.
>Centigrade, what should be done?
>
>Can the joint be accepted based on the hardness value?
>
>
>
>Please also provide references with your answer.
>
>
>
>Best Regards,
>
>Rishi Raj Singh
>
>________________________________
>
> From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of Prabhakar h
>Sent: 09 June 2008 16:25
>To: materials-welding@googlegroups.com
>Subject: [MW:835] Re: Clarification on Heat treatment-Reg.
>
>
>
>Dear Shabbir,
>
>
>
>Thanks a lot for your prompt response and sorry even i cud not catch up
>quite a while as i was held up with my ASME Audits.
>
>
>
>Your Explanation was usefull and it would be better if you cud tell us
>at what conditions we go for the HT and how the same is selected???
>
>
>
>Prabhakar.H
>
>
>
>On 5/4/08, shabbir ahmad <shabbir.ahmad7@gmail.com> wrote:
>
>Dear Prabhakar,
>
>
>
>Nortmalizing: The steel is heated 50 deg. cent grade beyond the upper
>critical tempreture( generally 900 to 940), once the calculated soaking
>time has elapsed the steel is removed from the furnce to cool in still
>air, This produce smaller n fine grain structure that has high toughness
>n strength.In short u can say normalizung makes steel tougher n strong.
>
>
>
>Stress Reliving: Steel heated upto 550-650 d.c..The plastic flow of
>sresses increased as tempr. rises, relieving locked in elastic residual
>welding stress.
>
>
>
>Tempering: The steel is re-heated after hardening and the balance of
>hardness & toughness is adjusted as the temp range 200 - 723deg. cent.
>
>
>
>at 723 d.c. all the martensite has been tempered removing the
>brittleness 7 returning the toughness and some ductility. Normally
>tempering carried out to rebalance the propertied of thermally hardened
>steels.
>
>
>
>solution Annealing : generally carried out on Stainless steel, this
>produces large n coarse grain.Heating the steel above 1040 deg.centi
>grade and quench in oil.
>
>
>
>Thanks
>
>
>
>shabbir
>
>
>
>On 5/3/08, Prabhakar h <hb.prabhakar@gmail.com> wrote:
>
>
>
>      Dear all,
>
>
>
>      Can anyone let me know what is the difference bet'n
>Normallising/Stress releiving/Tempering/Solution anneling..
>
>
>
>      I always get confussed and cudnt get a better idea....
>
>
>
>      Is there anyone to help it out....?
>
>
>
>      Prabhakar.H
>
>      </div
>
>
>>

Sachin.Sankhe
Engineer-Inspection
Aker Kvaerner-Malaysia
Mobile:012-2896901
Email1:Sachin.Sankhe@akerkvaerner.com
Email2:Sachin.sankhe@rediffmail.com

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