Restricted to limited specifications of steel seamless steel pipe, according to the needs of the end consumer so hot expanded steel pipe was born, the thermal expansion of pipe size models arbitrary, generally produced according to customer needs, the thermal expansion pipe is often said the thermal expansion of tubes, the density is relatively low but the contraction of the steel pipe of a strong (seamless pipe) can be referred to as thermal expansion. Expansion of the pipe diameter of a cross rolling method or the pull method