Sorry Bob this old Conn Yankee just has to ask. Is this rocket work, nascar,avaiton, structual iron? We are talking about holding the pieces of a fire pot together. Have seen one gas welded with coat hangers. Burned thru before the weld gave out. I don't see any issue with 60k over 70k. Course I run a gasser perhaps a coal forge develops more stress. Grin.
Ken.