Seamless pipe is formed from a cylindrical bar of steel. The bar is heated to a high temperature and then a probe is inserted to create a hole through the cylinder. The cylinder is then transferred to rollers which size the cylinder to the specified diameter and wall thickness.They are generally used for high-temperature and high-pressure equipment such as high-pressure oil pipes and high-pressure boiler tubes. Seamed steel pipes have lower pressure, and are generally used for low-pressure fluids such as water, gas, and compressed air.