Inst cruised to victory over Limavady Grammar with a seven-try show at Osborne Park to book their semi-final spot at Ravenhill
It was a thoroughly professional performance against a determined, albeit lacklustre Limavady.
It didn't take the home side long to break through the visitors' defence. After just six minutes winger Rory Campbell broke through some weak tackling to touch down in the corner. Nathan Brown couldn't add the extras but RBAI were up and running.
Inst's dominance in the opening quarter told as the visitors struggled to adjust to the pace of the game and they doubled their lead midway through the half when flanker Toby Boyd broke through more weak Limavady tackling, which was a feature of the first half. Brown's conversion sailed wide of the posts but the home side were in control at 10-0.
The visitors finally showed some attacking flair of their own and when Inst conceded a penalty for not rolling away from a ruck, Jack McCool slotted home the kick to reduce the deficit to 10-3.
Eight minutes later, they could have narrowed the gap to just four points but McCool's penalty attempt went agonisingly wide.
The Limavady players would have been happy to go in at the break seven points in arrears but Inst had other ideas and winger Iain Jones found himself in space and coolly ran in the home side's third try.
Things went from bad to worse for the boys from the Roe Valley as Inst started the second half with another another try, from fullback Fraser Wright.
Limavady's ill-discipline at the breakdown allowed the Belfast side to move deep into the visitors' 22-metre line midway through half. Inst produced a near perfect catch and maul from a line-out five metres out, only to knock the ball on at the crucial moment. However, they were not going to make the same mistake twice, and two minutes later another maul rumbled over the line and substitute Andrew McGrath got on the score sheet.
The visitors scored what was to prove a consolation try with 10 minutes remaining through winger Elliot and when the conversion was added it was 27-10.
Normal service resumed when Inst scored an excellent try, as Joshua Atkinson skipped down the touchline, eluding several covering defenders, to score in the corner.
The was still time for Inst to score again in the dying embers of the game and leave the coaches to reflect on the cup tie.
RBAI coach Richard Hedley was pleased with the victory but believes his side will continue to get better the more game time his players get.
He said: "The longer we can keep our boys on the pitch, the more training we can get them, the better we're going to get."
"We've a lot of pace, maybe today we were a little bit wide at times, but some of the play we thought was very good."
Limavady head coach Stephen Barr said: "I think we played the occasion rather than the game.
"We gave them all the momentum, and with momentum that gave them territory and field position, and it's very hard to come back from that."