Gate valves of the Theodore Roosevelt Dam in Arizona.
https://s3-us-west-1.amazonaws.com/h...s_fullsize.jpg
Previously:
https://www.homemadetools.net/forum/...880#post171413
https://www.homemadetools.net/forum/...994#post156992
https://www.homemadetools.net/forum/...158#post168849
https://www.homemadetools.net/forum/...134#post161016
https://www.homemadetools.net/forum/...758#post163556
