vcevidente,
With all due respect , pre heat is not always required. TIG welding is commonly used on thinner materials that do not require preheat.
The original question was too vague to be able to be properly answered by anyone on this forum,
Regards,
Shane
Good reply. The base metal composition or specification and thickness must be known before you determine if preheat is required. The preheat temperatures listed in D1.1 are the minimum preheat temperatures if the WPS is prequalified. While GTAW is listed as an approved welding process, I don't believe GTAW is one of the processes that qualifies as "prequalified" under D1.1. See reference 3.2.1 (I used AWS D1.1-2002). As such, the preheat temperature used to qualify the WPS comes into play.
Happy holidays and Merry Christmas
- One Wing, Al
I know some aerospace types that would have a coronary if someone told them preheating was always necessary.