In a high-scoring encounter, Williams' clinical finishing guided Pontypridd to a 48-26 win, one achieved against a Bedwas side who refused to give in.
It was an entertaining clash between the league's top two sides, played on a sunny April afternoon. Pontypridd had dominated the first half but only led 19-10 at the break, Williams and Huw Dowden with a try apiece. Replacement Rory Budina got Bedwas back into it with a scintillating finish while Dai Flanagan and Ethan Davies had kicked the rest of the points.
Bedwas narrowed the gap at the start of the second half through the boot of Davies and a James Benjamin try then gave the home side real hope.
But Williams completed his treble and Cory Hill and Owen Jenkins added the final two scores at the death.
It had been a superb start for Pontypridd, Flanagan opening the scoring with a simple penalty before Williams went over for his twelfth try of the season. In the April sunshine and on a dry pitch, Pontypridd were enjoying the chance to through it about and following some impressive ball retention, Flanagan spread the ball right for the winger to go over in the corner.
The Pontypridd fly-half missed the conversion but his side were well on top, two further penalties giving them a 14-0 lead after 20 minutes. It could well have been more, a quick tap from Flanagan nearly creating a score for Jenkins while only a knock on from skipper Chris Dicomidis stopped the visitors finishing off a length of the field move.
Bedwas were struggling to get into the game, ex Pontypridd scrum half Tom Rowlands trying desperately to cajole his side back into it before the Gwent outfit were hit by a double blow. First wing Matthew John was forced off injured to be replaced by Budina, then prop Kristian Gay was yellow carded as Leighton Hodges lost patience with the Bedwas forwards.
With a man advantage, the outcome was almost inevitable and Pontypridd soon added a second try, Dowden burrowing over to maintain his impressive recent scoring record. Flanagan's kick struck the upright before Bedwas, remarkably, got back into things.
Being a man down didn't seem to bother the men in black and Davies got them on the scoreboard with a long range penalty. They then narrowed their deficit further, Budina racing clear for a sublime solo effort. The replacement, who boasts a superb scoring record against Pontypridd, escaped the covering defence and stepped past a last ditch Flanagan tackle to score under the posts.
Davies converted and despite Pontypridd dominating most of the first half, the home side only trailed by nine at the break.
Inspired by their strong finish to the first period, Bedwas looked a different side after the break, forwards and backs interchanging nicely. Davies added a second penalty and saw a third effort go wide via a post as Bedwas camped themselves in the Pontypridd half. But a try failed to materialise and when Rhys Shellard picked off an interception, the men in pink added their third score of the day.
Shellard showed all of his sevens ability to intercept and race clear, then keeping hold of possession when the tacklers arrived. The ball was recycled to Flanagan, his superb cross field kick finding Williams in acres of space out wide. The wing dotted down under the posts for his second of the day, Flanagan kicking the simple conversion.
Bedwas had refused to lie down all day though and they weren't about to start now. Davies kicked a third penalty before replacement Benjamin picked up a loose ball and raced clear to score. Davies converted and Bedwas trailed by just three.
Despite there being little between the two teams on the scoreboard, there remained a feeling Pontypridd could score when they fancied though and Williams soon completed his hat-trick.
Davies replied with yet another penalty but Flanagan converted final scores from Hill and Jenkins to secure the win.