Overnight joint-leader Kiradech carded a five-under-par 67 for a total of 13-under 131 to lead countrymen Chawalit Plaphol and Thanyakon Khrongpha in the $300,000 event, the first on the Asian Tour calendar.
Australian Marcus Both, Joonas Granberg of Finland and Hung Chien-yao of Taiwan were a further shot behind on 134 at the close of the second round at the Royal Mingalardon Golf and Country Club.
Defending champion Kieran Pratt, who beat Kiradech in a play-off last year, was disqualified for arriving late for his tee time while overnight co-leader Chapchai Nirat of Thailand shot a 72 to lie tied 10th.
Kiradech mixed six birdies with a lone bogey on Friday to follow-up on his opening round 64.
"I've had a lot of experience in the last few years of being in contention and winning," Kiradech, 23, said.
"Right now, I'm not thinking about winning yet because it isn't the last day yet.
"I have two more rounds and I want to do my best and give myself a chance."
The Thai could have carded a lower score to widen the gap at the top but struggled a bit with his putting.
"I feel my putting stroke isn't as smooth as it was yesterday but I won't do much change, just tweak a bit of my back swing," he said.
Both, twice a winner on the Asian Tour, made the turn on 29 with seven birdies but the 33-year-old lost steam in the back nine with consecutive bogeys on the 16th and 17th holes to finish on six-under 66.
"It was nice. It might sound very stupid but I didn't play that well," said Both, who hit the second-lowest first-nine score on the Asian Tour.
"I sort of hit everything nicely on the greens and holed everything. I had nine one-putts on the front nine. That was pretty much the reason why.
"I hit it okay but not amazingly well. It sort of caught up with me on the back nine."
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