PTFE lined steel pipes are primarily used for conveying highly corrosive acids (like sulfuric or hydrochloric acid), strong alkalis, and high-purity chemicals. They are essential in chemical processing, semiconductor manufacturing, and pharmaceutical plants. The operational temperature range is generally between -29°C and +260°C. However, you must confirm the pressure-temperature rating with the supplier, as the allowable pressure drops significantly as the temperature approaches the upper limit.