In order to carry out the root passes with GTAW process, we use the argon for backing, at the same time we have to preheat and maintain temperature at 200°C. My question is what types of dames must we use in this case?
My favorite method was to use Kaowool strips rolled into a dam and then the hose stuck through the middle. It ain' airtight but it is well sufficient with a strong positive flow.
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