My posts are recycled 4" galvanized tubular steel (hot-dipped?). Found 'em at the metal recyclers and the guy GAVE them to me. I don't know what "schedule", but the 10ft pieces weigh maybe 80lbs. As far as I know, they are regular fencing gate or corner posts.
They showed no signs of deterioration when I got them except that they had obvious signs of having been partially encased in concrete. I've had them up for maybe 5 years and they are showing zero signs of any deterioration. Unbelievably rigid with a 16ft swing gate. Almost zero deflection even when standing on the far end of the gate. I do have them concreted (grouted) into 4ft deep holes drilled into rock, backed up with a 1/2" rebar "pin".
They showed no signs of deterioration when I got them except that they had obvious signs of having been partially encased in concrete. I've had them up for maybe 5 years and they are showing zero signs of any deterioration. Unbelievably rigid with a 16ft swing gate. Almost zero deflection even when standing on the far end of the gate. I do have them concreted (grouted) into 4ft deep holes drilled into rock, backed up with a 1/2" rebar "pin".