Explain the procedure for performing an internal inspection of sprinkler piping to detect corrosion and obstructions.

Performing an internal inspection of sprinkler piping is crucial for identifying corrosion and obstructions that can compromise the system's effectiveness. The procedure begins with isolating a section of the sprinkler system to be inspected. This involves closing the appropriate control valves and relieving the pressure in that section of pipe. Next, an access point is created in the piping. This can be done by removing a sprinkler head, a fitting, or by installing a temporary access port. A video borescope or a similar inspection device is then inserted into the piping. A video borescope is a flexible tube with a small camera and light source at the end, allowing for visual inspection of the interior of the pipe. The borescope is advanced through the piping, and the interior surfaces are carefully examined for signs of corrosion, scale buildup, sediment accumulation, or other obstructions. The inspection should focus on areas that are most susceptible to corrosion and obstruction, such as low points in the piping, dead-end sections, and areas near fittings and valves. Any corrosion or obstructions that are found should be documented, including their location, size, and severity. Photographs or videos can be taken to provide a visual record of the findings. The extent of the corrosion or obstruction should be assessed to determine whether cleaning or replacement of the piping is necessary. After the inspection is complete, the borescope is removed, and the access point is sealed. The section of the sprinkler system is then re-pressurized and tested for leaks. The findings of the internal inspection are documented in a report, along with any recommendations for corrective action. If significant corrosion or obstructions are found, a more extensive inspection of the entire sprinkler system may be warranted. It's also good practice to flush the system after an internal inspection, removing any loose debris dislodged during the inspection process.