This paper discusses the development and actual site testing of an inspection robot designed for boiler header inspections in thermal power plants in Malaysia owned by Tenaga Nasional Berhad (TNB). The purpose of boiler headers are to tie up multiple boiler tubes together. Boiler headers are enclosed cylindrical pipes made of carbon steel, horizontal in nature, can range up to 25 m (from TNB database). These boiler headers are highly pressurized and high in temperature during operation, where the pressure goes up to a few bars and the temperature ranges between 500°C until 800°C. Due to the severe working conditions, these boiler headers are exposed to threats of possible failure due to corrosion, pitting and cracks. During outage, after acquiring approval from Department of Safety and Health (DOSH), a small cut is made on the entry point and a boiler header inspection robot (BHIR) is then deployed into the boiler header, carrying a fiber optic camera. BHIR is developed to visually inspect the inner wall of boiler headers and check for signs of failures. This paper discusses the limitations and requirements of the robot, the prototype and also the procedures for actual site testing. Lastly, the site testing results is explained.