Re: [MW:13092] Preheating temperature of 2nd process when use two welding process in one single joint (GTAW+SMAW)

Hi Aly,

Preheating is which we apply heat on welding area including heat affected zone to control cooling rate. Means while you will start the welding ur heat affected zone will be less and there is a chance of crack in heat affected zone in high integrity and high thickness materials. While u apply sudden heat by welding on thick material or high integrity material the heat in all area will be different so. So u have to maintain the cooling rate. 

Then in the case of ur PQR which is the material u used. Do that need pre heat. 

Where u measured the temperature.

If u continued welding without delay , it is not preheat temp ,it is inter pass only. Preheat is done prior to welding starts. If you stop and start need preheat. If u continue without delay , changing process also will no need preheat , unless ur inter pass is get done from the desired one for the material grade and thickness.

Heat should to be measured on heat affected zone.

This is according to my knowledge.....

Regards,

sojin.k.soman

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From: Aly <mhaskar.aly@gmail.com>
To: materials-welding@googlegroups.com
Sent: Tuesday, November 29, 2011 2:40 AM
Subject: [MW:13083] Preheating temperature of 2nd process when use two welding process in one single joint (GTAW+SMAW)

Dear Experts,   When we are using two process (GTAW + SMAW) on pipe test coupon of a PQR, Root run & hot is done with GTAW process, immediately after hot pass we have started SMAW process,   Prior to start of SMAW process, temperature of coupon noted was 95 deg C   My question is whether this 95deg C will be considered as preheating temperature for SMAW process   Kindly advise in the light ASME Codes   Thanks in advance   Mhaskar Aly UAE

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