Hansen, who won the 100 breaststroke on Tuesday to qualify for London in that event, finished his semifinal Thursday in 2:10.45, 0.44 seconds behind top qualifier Clark Burckle.
"This is a race that I think I'm better at than the 100," Hansen said, even though his disillusionment with finishing fourth in the 200 at the 2008 Olympic trials pushed him toward a brief retirement from swimming. "If there's a chance for me to medal in London, I think this is a better shot."
Hansen, 30, won silver in the 100 and bronze in the 200 at the 2004 Olympics. He is a two-time world champion in each event.
"The 100 is always going to be a crap shoot no matter what, but the 200 is really just kind of bearing it down," said Hansen, who grew up in Havertown.
Crippen, 22, scratched three races and didn't advance out of preliminaries in a fourth earlier in the trials because of the flu.
"I felt really comfortable," she said of her race Thursday. "I definitely pushed it a little bit in the middle, just to see where I was."
In Friday night's final, the Germantown Academy graduate will be in a lane adjacent to a swimmer who, like Crippen, is swimming with a heavier heart than most at these trials.
Kathleen Hersey, who had the second-fastest qualifying time in the 200 butterfly, lost her mother to cancer in January. Crippen, whose brother Fran died in an open-water swimming race in October 2010, "was one of the friends that I leaned on more than she knows," Hersey said, "just because I saw how well she dealt with Fran's passing.
"She understood it a different way," Hersey said.
Crippen made Hersey, a Georgia native who swam at Texas, a plaque. The plaque, which Hersey hung next to a photo of herself with her mother, reads: "God has three answers to your prayers - yes, no, I have something better in mind."
Something better might happen Friday night.