Re: [MW:27766] AWS D 1.1 interpretation on Increase in Preheat / Interpass temperature

hello, 

The Maximum preheat or interpass are the same and shall be 173° c as per PQR. 

30°c in the PQR is minimum temperature observed during PQR welding...So to interprete Code sentense, 30°c is minimum and 173°c is max preheat observed...110°c shall not be issue.

So i feel Your client needs to be discussed and explained this way...

On Wed 2 May, 2018, 6:59 PM Kannayeram Gnanapandithan, <kgpandithan@gmail.com> wrote:

pl ref AWS D 1.1, Table 4.6,7

Preheat/Interpass Temperature

7) An increase of more than 100°F [56°C] in the maximum preheat or interpass

temperature qualified

THANKS & BEST REGARDS,

KG.PANDITHAN, BE, IWE,  AWS-CWI, CSWIP 3.1,

CONSULTANT-WELDING & QUALITY

Mobile no: +919940739349

On Wed, May 2, 2018 at 3:50 PM, 'wilfred kojo' via Materials & Welding <materials-welding@googlegroups.com> wrote:

Increase in preheat temperature is not essential variable; decrease in preheat temperature is essential variable. 

Increase in inter-pass temperature is supplementary essential variable (applicable only when notch toughness is required).  

Any client who claims increase preheat temperature is essential variable does not understand the code requirement.

On ‎Wednesday‎, ‎2‎ ‎May‎ ‎2018‎ ‎04‎:‎58‎:‎49‎ ‎WAT, N VENKATESWARA PRASAD <weldengr.velosi@gmail.com> wrote:

Dear Experts,

We have received a comment on Increase in Preheat temperature greater than 56°C is essential variable as per AWS D.1 from our client.

My interpretation is the increase in 56°C is applicable only for inter pass temperature.  The details are as given below. 

 

PQR   Test coupon thickness        :  30 mm

PQR   Preheat temperature          :  30°C

PQR Inter pass temperature        :  173°C

 

Job Thickness                                  : > 38 mm  to 65 mm  ( As per Table 3.3)

Preheat temperature                    :  110°C

Inter pass temperature                 :  220°C

MDMT                                               :  -40 °C

 

As per AWS D 1.1  Table 4.6  Point no. 7   an increase more than 56°C in max preheat or interpass temperature is essential variable  for CVN testing applications.

 

Based on the above clause, the client is insisting that the Qualified Range for  thickness in WPS shall be restricted to 38 mm as the preheat is increased from 30°C to 110°C which is not acceptable .

 

Please provide me if you any interpretation on it from AWS.

Regards

Prasad

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