I am not able to use prequalified rules for Minimum Preheat and based on my steel I have to use the Hydrogen Control Method I6.2.    Based on my Pcm being <.18 and my max thickness of 38mm and understanding that I will be welding small .13mm brackets to large 38mm plates, I am confronted with the question:  Do I use Low or Medium restraint? 

If I use Low Restraint I can weld this with any electrode and no preheat. 

If I use Medium Restraint I will have to use a low hydrogen electrode with no preheat but I will have to condition the electrode or if I don’t use a low hydrogen electrode I will have to preheat.

I will be MPI testing each one of these brackets so I should have the ability to detect cracking.

Which way do I go?