Abstract: Decapping system and methods of performing a decapping process for screw cap test tubes. In an embodiment, a method comprises loading a test tube rack in a rack holder that holds the test tube rack stationary, where the test tube rack holds the screw cap test tubes aligned in a row. The method further comprises clamping the row of the screw cap test tubes between a pair of jaw members of a row clamp, where clamp surfaces of the jaw members apply a force to opposing sides of the row of the screw cap test tubes. The method further comprises successively contacting screw caps of the screw cap test tubes in the row with a rotating bit of a decapper tool to spin the screw caps in a loosening direction.