Repeat of PWHT cycles can reduce toughness and tensile strength, to know exactly how much will be reduction, it can only be evaluated by qualifying a PQR, usually base metal MTR will have more strength than minimum specified so strength may not be a problem similarly toughness also should not be below minimum requirements.
If you are using original WPS for repair weld then QW-202.3 and QW-407.2 is applicable, WPS needs to have been qualified with at least 80% of the aggregate time at temperature during production welding. Aslo bear in mind some additional requirements mentioned in Appendix R & C in API 5L spec.
If i were you, I would have qualified a repair PQR considering above mentioned point and if all the mechanical results are satisfactory then CPY will be happy to accept it, after all it's just a recommendation.....
Regards
Manpreet Singh
On Tue, 11 Jan 2011 01:57:25 +0530 taufiq rahman
>
Dearexperts,
Here itis what I'm looking for. Too much heat input and longer time for PWHT will significantlyreduce toughness and mechanical properties. Can you explain me in more detail? what is happen with chemical composition? Fyi, after verifying document, I found that severalwelds have been repaired until 3 times, and the system already put in service.
Note:mat'l spec: API 5L Gr B, process: SMAW, root pass: E6010, hot pass:E7018,design code: B31.4
I'mtrying to get a good answer from experts.
Thanksin advance.
>
Dari: manpreet <manpreetsin88@rediffmail.com>
>Kepada: "materials-welding@googlegroups.com" <materials-welding@googlegroups.com>
>Terkirim: Sen, 10 Januari, 2011 10:17:59
>Judul: Re: [MW:9161] Weld Repair
>
>Dear Taufiq,
>
>Since there is not sufficient info provided, I can give you a general idea:-
>
>Repair Welding Procedure often requires PWHT, Repeating weld repair would cause too much heat input and longer time for PWHT which would significantly reduce toughness and mechanical properties, also If you are qualifying wleding procedurein accordance with ASME sec ix make sure you fullfil the requirements of QW-407.2.
>
>Regards
>Manpreet Singh
>
>
>On Sun, 09 Jan 2011 09:17:34 +0530 Shanmugam Palanisamy wrote
>>
Dear Taufiq,
Doing welding many time atthe same location, the base matel mechnical properity well get change. To avoid the properity change, better to cut and reweld.
regards
Samy
>>
>>
>>
>>
On Sat, Jan 8, 2011 at 4:34 AM, Taufiq <taufiq_civ@yahoo.com> wrote:
>>
>>
Dear all,
>>
>>Our client specification clearly stated that filler and cap weld may
>>be repaired a maximum of 2 times using qualified procedure. I will
>>appreciate if anyone can tell me what is going on if we repair the
>>weld for more than 3 times?
>>
>>Thank you and regards,
>>
>>taufiq
>>
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>
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