Hampton missed his second straight game with a knee injury while Smith missed his second in a row with a foot injury. Chris Hoke started at nose tackle for Hampton, while Ziggy Hood started for Smith.
Cornerback Derek Cox, linebacker Clint Session, running back Montell Owens, center Jason Spitz, guard Eben Britton, wide receiver Kassim Osgood and defensive tackle Nate Collins were inactive for Jacksonville.
The Steelers held on to win 17-13.
Information from The Associated Press contributed to this report.