Here is a close up of the head flange welds. The discoloration on the pipe is what looks like clear flux that comes off with your fingernail. They must have used a 309L filler wire with a flux core. Those are actually 3/8” head flanges, not 7/16” as advertised. One thing I have found with 7/16” head flanges is that you need to go up to the next length bolt which is more difficult to install.