The only goal of the game was scored by teenager Mpho Padime in the first half as the home side eased to victory.
Sekhukhune will be sick of the sight of the Buccaneers, having now lost to them four times this season following two MTN8 semi-final defeats across the two legs and a league loss.
The Limpopo club have failed to score in any of those games and conceded seven goals.
Padime netted from close range in the 32nd minute after the ball fell kindly for him following a deep cross to the back post.
He showed good composure and awareness to stab the ball into the back of the net.
Pirates were perhaps fortunate when Simphiwe Selepe was not showed a red card for a late challenge in the first half that on another day might have seen him taking an early shower.
Pirates largely dominated after that and Tshepang Moremi wasted two gilt-edged chances, first completely missing the ball from six yards out before blazing another effort well over the crossbar when under no pressure.
Given his excellent form in front of goal this season, he would have been expected to convert at least one of those opportunities.
Pirates join Mamelodi Sundowns in the semi-final draw, which will take place after the final two quarter-finals on Sunday.
Kaizer Chiefs host Siwelele in Polokwane, while in-form AmaZulu travel to Stellenbosch FC. Both matches kick off at 18h00.