Wednesday, September 8, 2010

Re: [MW:6933] P11 & P22 Hardness Issue

As per codes the values u hav got will not be allowed..upto 270 can be accepted and no way more than 300 can never be accepted..

Next to this more the hardness value indicates, it needs to soften(toughen) the material that means it needs to do PWHT again at 640deg  and soak for specified time (depends on thickness).. and for p22 PWHT at 720deg and soak for specified time (depends on thickness).

Joint will become hardner and may have chance for cold cracking ( long time service failure )

Generally HAZ hardness shall be more than weld hardness for p11 and p22 but in practical i got the hardness values at HAZ always lower than weld..i think repeating PWHT will not affect HAZ hardness



On Wed, Sep 8, 2010 at 9:55 PM, Ashfaq Anwer <ashfaqanwer@thepetrostreet.com> wrote:

We are facing one serious concern regarding PWHT of weld joints of A335 Grade P11 & P22 piping in very high pressure superheated steam and syn gas service. Due to some unforeseen circumstances at our site, PWHT of some weld joints was not done effectively and resulted in higher hardness of weld joints although HAZ area hardness values are OK. The hardness number of weld joints is in the range of 260 - 320 HB which is unacceptable as per code requirements.

I want to seek expert opinion on the following:

1. Can we take these weld joints is operation and defer PWHT for planned Outage in April 2010?

2. Is there any relaxation which can be taken in hardness readings, for example, welds with hardness up to 260 may be accepted and above this number must be PWHT again?

3. What effects can it cause after taking these weld joints in service? Weld failure can occur immediately or would take some time?

4. As HAZ area hardness number is standing in the range of 115 - 150, would repeating PWHT effect this number and further reduce the hardness of HAZ which may not be acceptable?

Your inputs would definitely help me in making a correct decision.

 

Regards,

Ashfaq

 

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Regards,

Mohan Murali.B
Asst.Manager,QA(Cab&Cowl)
TATA Motors Ltd.,Jamshedpur
Mobile No:+919534084118

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