A close opening round ended three points apiece, but Pongprayoon was looking like the smoother operator.
The Thai continued to get the better of his opponent in the second round and edged ahead 9-8 as they entered the final three minutes.
Ayrapetyan was having an off day and showed none of the skill that he is capable of. He was being beaten to the punch time and time again as Pongprayoon closed in on victory.
The judges awarded the Thai a 13-12 verdict.