that is an interesting pipe wrench. Cope's American Wrench Makers book has Rigid's 3 patents issued to
W.O.Thewes. Aug. 11, 1925, Sept.1, 1925 & Dec.15, 1925. the one you have with the Patent # 1727623
was also patented by William O. Thewes of North Ridgeville, Ohio on Sept. 10, 1929. the patent application
states that it is for a jaw on an angle for better gripping. (nice one to add to a collection.) Frank