Those are called riser clamps and are used to support black iron heating pipes and are plenty strong,I think it is the bend and crimp in them that has all the strenth,my tower has withstood all that has been blown at it and living on the coast in Nova Scotia we get some good gales. So far this month we have had about a week of weather with winds in the 50 to 80 km range with gusts well above that. Unless someone climbs up and takes the bolts out of these clamps I wont worry about the joints. I feel doing it this way gives me three things that have to fail before the joint would ever come apart, threads would have to give way,weld would have to break and bolts would have to come out of riser clamps. might not be pretty but works like a charm!
(sorry for the dbl.pic) I wanted to show the pivot I made for my tower from ideas posted here.. Thanks
