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Re: [MW:27681] Preheat temp lower limit from min temp teg

By Materials & Welding
this is not correct. You should not confuse PQR range with Construction Code requirements.
Example;
B31.1 requires for P91 according to the table 131.4, 200 degC. The validity of the PQR for a lower temperature does not overrule the construction code requirement

2018-04-05 10:37 GMT+03:00 'Karthik' via Materials & Welding <materials-welding@googlegroups.com>:
Hi,
Assumed your construction code is ASME, according to ASME Sec.IX , QW 406.4, It allows preheat temperature can decrease upto 55 degree C than qualified WPS.  Code just gives recommendation for pre heat temperature of minimum 205 degree C but we should follow as per our engineering practice.i.e set up to 240 to avoid temperature reduce while opening heating pad.
In your case , Please check your thermocouple/monitoring thermo couple positions. It might be attached away from the weld location. And also you said during welding. if so, did you verify the temperature before start weld? Once you open the heating pad for welding, you should verify once again with infrared thermometer at weld location before start weld. If you verified and no way to reduce below the temperature you measured during weld.
If you found the temperature measured is less than 205 degree c you dont start weld.
please set preheat temp. to 230 to 240 atleast so that when you open the heating pad it might not be reduced below 205.
Check monitoring thermo couple location which should be as much closer to weld location and also verify again with infrared thermometer before start weld.

Thanks& Regards,

 

(Karthik)

Karthikeyan.S

QA/QC Manager
Agon Pacific Co.,Ltd.
M: +66-655-174-397, +66-892-512-282

E-mail : karthik6684@yahoo.com



On Thursday, April 5, 2018, 1:28:04 PM GMT+7, Kannayeram Gnanapandithan <kgpandithan@gmail.com> wrote:


what is welding process and code of contrustion

THANKS & BEST REGARDS,
KG.PANDITHAN, BE, IWE,  AWS-CWI, CSWIP 3.1,
CONSULTANT-WELDING & QUALITY
Mobile no: +919940739349

On Wed, Apr 4, 2018 at 2:11 PM, 'smkabeer ahamed' via Materials & Welding <materials-welding@googlegroups.com> wrote:
Dear sir
Item description evaporator outlet header
Material Sa335 P91
Preheat temp 205 deg c min
Process. Induction heating
During welding preheat temp comes to 197 deg c. Please clarify either it is accepted or not.
If it is Accepted please provide relevent standards.  

Thanks and regards
S.M.Kabeer Ahamed
Quest Pvt Ltd Bangalore
9168605601

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Dr. Georgios Dilintas,
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Welding, Stress Analysis, Corrosion, QA/QC, Failure Analysis, Risk Analysis

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