Impossible Street Elbows

All four pieces of this puzzle are plumbing street elbows made of iron. Quality of construction is very good and the puzzle is coated with a sealant to prevent rusting.

The 4 Street Elbows is an "impossible object" consisting of four standard-looking plumbing elbows, joined (and held together) by the screw threads of each elbow. The pieces have not been joined by welding or gluing.  The pieces are held together by their own threads.

Designer Saul Bobroff claims that there is only one person who has removed the elbows and put everything back into the solved state. Could you be the second?