There has been some issues regarding the new D1.1 preheat requirements (minimum and maximum) for some moment frame columns that are being fabricated at a shop here in oregon. As the D1.8 does not address material thickness my question is this, on a high heat input weld connection (cjp) on a seismic resisting moment frame what are the preheat requirements according to D1.8?
Loudog I also did not find any supplemental preheat requirements other than you might have when using a PQR to get the WPS. Sense the D1.8 is supplemental to the D1.1 using the D1.1 table 3.2 seams to be your option except the interpass maximum is 550 degrees (D1.8-6.5.1) or 400 to 450 degrees on certain other steels. (D1.1 table 3.2 note c) If you did do a PQR then the preheat used (if any) on it would now be your preheat on your current WPS.
The D1.8 Table A.1 (pg 25) shows suggested heat input along with preheats for Demand Critical Welds filler metal testing requirements.
You do want to slow down the cooling rate but not too slow. You did not state what steel you're welding nor the thickness along with the kJin & process, all would be needed to analyze the application a bit better.
Someone else may be able to give you a better direction. Just some thoughts
I don't hve a copy of D1.8 here in my hotel room, but I believe D1.8 is to be used in conjunction with D1.1. As such, the preheat would be in accordance with D1.1. Heat input limits would be as qualified per D1.8.
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