Vale fly Championship flag in the Swalec Cup quarter-finals.
The Gwent hosts crossed for six tries, three coming in the opening 20 minutes, as the Steelmen got off to an explosive start.
Ross Jones went over inside two minutes before Wes Cunliffe went in at the corner for a second on six minutes.
Vale's strong pack saw Cameron Regan claim a pushover score.
An accidental collision led to a nasty injury to RGC's Rhodri Carlton-Jones, who had to be stretchered off, but the visitors' fortunes received a boost when fly-half Lewis Barker crossed for a brace before the interval, both of which he converted.
But Jason Strange's charges were proving strong up front and were awarded a penalty try which Iain Smerdon converted.
The hosts strengthened their grip on the tie when Luke Davies crossed in the corner, but the visitors showed great spirit for Richard Hopkins to score a fine try following a smart move. Barker converted and added a penalty to take his personal tally to 21 points. But the hosts closed out the game to earn a home tie with Llandovery, with a Smerdon penalty and conversion of a second pushover score by Regan.