Converted tries from Sam Arnold, Darren Sweetnam and Chris Cloete, with the first two coming while Ospreys flanker Will Jones was in the sin-bin, catapulted Munster into a 24-5 interval lead.
Jeff Hassler squeezed in a late reply before half-time, but Rory Scannell bagged the bonus point early in the second half before the Ospreys, who were missing 22 players due to Wales commitments and injuries, cancelled out a Jack O’Donoghue effort with a 70th-minute consolation score from teenage openside Jones.
Munster hit the front inside five minutes, Sam Davies being blocked down by Scannell and an infringement at the breakdown allowed Ian Keatley to kick the hosts ahead.
Davies’ penalty kick to the corner was then overcooked after the Ospreys turned down a shot at the posts. An Olly Cracknell surge set up a promising spell on the quarter hour mark, but Jones, on his first PRO14 start, saw yellow for a neck-high tackle on Cloete off the ball.
A bout of handbags ensued on the touchline, but when play resumed, Munster did the damage on the scoreboard as they turned a lost Ospreys lineout in the visitors’ 22 into a try, centre Arnold bursting onto Keatley’s delayed pass and fending off James Hook to run in behind the posts.
Keatley converted and he also played a central role in Sweetnam’s 22nd-minute try, outmanoeuvring Tom Habberfield as he attacked the space out to the right wing. Sweetnam and Cloete combined before the latter’s pass back inside went to ground, but the Cork-born winger was able to snap up the loose ball and roll over the whitewash.
The extras were added by Keatley and a bout of scrum pressure, five metres out, soon had Munster knocking on the door again. The Ospreys fell asleep when Cloete was tackled, but with no ruck, he released the ball and picked it again to slip through for an opportunist score – rubber-stamped by TMO Sean Brickell – in the right corner.
Keatley swung over another pinpoint conversion, before Munster switched off in the dying minutes of the first half as Kieron Fonotia broke Sweetnam’s tackle to send Canadian international Hassler over in the left corner.
Some lovely interplay between Alex Wootton and Scannell saw the latter cross for a 42nd-minute converted try, throwing a neat dummy along the way. Hunting for a try himself soon after, the ball just beat Wootton over the sideline from a kick through by man-of-the-match Rhys Marshall.
As Scannell’s boot pinned the Welshmen back, Robin Copeland scooped up turnover ball in the 22 and captain Billy Holland provided the scoring pass for O’Donoghue, 55 minutes in.
Keatley’s only missed kick of the night preceded a strong final quarter from the Ospreys. A flurry of penalties in the Munster 22, including a cynical offside from O’Donoghue which earned him a yellow card, eventually saw Habberfield put Jones over neat the right corner.
South African van Graan will have been disappointed with Munster’s indiscipline as the focus now switches to their European double header with Leicester Tigers, while prop Liam O’Connor’s leg injury, which forced him off on a stretcher, is also a concern.