Dale Steyn, after languishing on the bench for all but one match in the IPL, bounced back in great form to take 4-18 for Glamorgan.
He effectively ended Kent’s hopes by taking three quick wickets as they set out to chase 175 in a match reduced to 16 overs by rain.
Glamorgan owed their formidable challenge to a stand of 132 between David Lloyd (97) and Colin Ingram, who hammered 60 off 29 balls (6×4, 4×6) after Jacques Rudolph fell for 8.
Ingram has made 95 not out and 85 in his last two innings and his 60 here was a continuation of that fine form.
Steyn conceded just one run, a wide, before taking the wicket of Daniel Bell-Drummond.
He bowled three consecutive overs and claimed a victim in each of them as Kent stumbled to 30-3 at the end of the fifth over. Steyn now has nine wickets in four innings in the series, from 14.3 overs, at an average of 10.33, assisting Glamorgan to the top of the South Group with just one loss in six matches.
Players battled to get game time in one of the wettest Junes in recent history, but one who did was Roelof van der Merwe, who took 3-16 in a losing cause as Somerset went down to Gloucestershire. Chris Gayle shone, scoring 40 off 26, but his team-mates struggled, until a late assault from Lewis Gregory (23) and Van der Merwe (18) took Somerset to a vaguely competitive score.
Van der Merwe reduced Glos from 103-2 in the 13th over to 111-5 in the 15th, but it was too big an ask without substantial support. Gloucestershire captain Gareth Roderick, the Maritzburg College OB whose career was kick-started at KZN-Inland under 19s, finished it off with 22 off 16 balls.