PURPOSE: To manufacture a high quality and cheap long-size pipe-clad steel of excellent weldability by the procedure in which a doubling material is attached closely to the inside of base metal, the end portion between the doubling material and the base metal is sealed by welding, and then the doubled metal is hot rolled with a specific draft in a specific temperature range.

CONSTITUTION: A doubling material is attached closely to the inside of base metal, the end portion between both materials is sealed by welding, and then the doubled metal is hot rolled with a draft of more than 15% for the first rolling in a temperature range from 850 to 1300°C. Furthermore, in case where a closely touched or jointed pipe in which doubling material is not almost closely attached to the inside, outside, or both sides of base metal, or is not completely attached to them, the end portion between the doubling material and the base metal is strongly fixed by padding welding and then hot rolled with a draft of more than 15% for the first rolling in a temperature range from 850 to 1300°C. Also, as a means of closely sealing the end portion between the doubling material and the base metal, an explosive pipe expanding method, a gas explosion method, etc., using a filling medium for the end portion between them, etc., may be used.