Sipp was designated for assignment by the Nationals on Friday, Mark Zuckerman of MASN Sports reports.
Sipp has struggled through 36 appearances this season for the Nationals, posting a 4.71 ERA and 1.33 WHIP with an 18:9 K:BB over 21 innings, and the acquisition of Roenis Elias removed the need for his services from the port side. He'll head to waivers following this latest roster move.