Nirat posted a second-round, 6-under 66 to complete two rounds at 17-under-par 127, and has a six-shot advantage after matching David Howell's 36-hole record from last year.
'I just want to make as few mistakes as possible,' said Nirat, who tied for eighth place at this year's Indonesia Open. 'I'm quite happy with my golf right now. The previous two weeks was not so good, but I feel comfortable this week.'
Rafael Echenique (69), Adam Blyth (66), Jean-Baptiste Gonnet (66), Simon Nash (66) and David Bransdon (66) are knotted in second place at 11-under-par 133.
Nirat started with two birdies in his first three holes, then dropped his first shot of the tournament at the par-4 fourth, a hole he birdied on Thursday.
That would be Nirat's last miscue of the round. He birdied the par-four seventh for the second time in as many days, then parred his last two holes of the front nine to go out in 2-under-par 34.
Nirat parred his first three holes of the back nine, but was still in the lead at 13-under par. He rattled off back-to-back birdies from the 13th, then eagled the par-5 16th to get to minus-17.
Nirat parred his final two holes to put his name next to Howell's in the TCL Classic record book.
'The only thing on my mind was to keep hitting fairways and keep making putts,' said Nirat, who equaled the low 36-hole mark in Asian Tour history, a circuit that co-sanctioned this event with the European Tour. 'I just wanted to ensure I didn't make any mistakes. Today my irons were good, my putting was good. Everything was very good.'
Another thing that should be on Nirat's mind is what happened last year to Howell. The Englishman only went 3 under par the rest of the tournament and lost by five strokes to Johan Edfors.
'I still feel a bit of pressure because I know that on a course like this it's possible for someone to catch me, so tomorrow I still have to score low,' said Nirat.
Unfortunately for Nirat, his closest pursuers are also aware of recent history.
'He's obviously playing tremendous golf, but I played here last year when David Howell was 17 under after two rounds and he didn't win,' said Carl Suneson, who is tied for seventh place at minus-10. 'This game has a habit of bringing you back to your knees pretty quickly.'
Wen-teh Lu (69), Taichi Teshima (65), Brad Kennedy (67) and Carlos Rodiles (66) joined Suneson, who posted a 4-under 68 on Friday, seven shots behind Nirat.
The 36-hole cut fell at a staggering 5-under-par 139 and among the notable players to miss the cut were Joakim Haeggman (140), Ignacio Garrido (142) and former Ryder Cup captain Ian Woosnam (143).