Methods and systems for providing cleaning and providing barrier coatings to interior wall surfaces of small diameter metal and composite piping systems in buildings. An entire piping system can be cleaned in one single pass by dry particulates forced by air throughout the building piping system by an external generator, and the entire piping system can be coated in one single pass by a machine connected exterior to the piping system. Small pipes can be protected by the effects of water corrosion, erosion and electrolysis, extending the life of piping systems such as copper, steel, lead, brass, cast iron piping and composite materials. Coatings can be applied to pipes having diameters of approximately ⅜″ up to approximately 6″ so that entire piping systems such as potable water lines, natural gas lines, HVAC piping systems, drain lines, and fire sprinkler systems in single-family homes to apartments to high-rise hotel/resort facilities and office towers, apartment and condominium buildings and schools, can be cleaned and coated to pipes within existing walls. The coating forms an approximately 4 mils or greater covering inside of pipes. Buildings can return to service within approximately 24 to approximately 96 hours.