PURPOSE: To uniformly and smoothly coat an inner surface of a metal pipe and to sufficiently bring it into close contact with the inner surface irrespective of a length, a diameter of the pipe by inserting a tube made of a soft film of synthetic resin into the pipe, pressure-reducing a gap by suitable pressure reducing means, and bringing the tube into close contact integrally with the inner surface of the pipe.

CONSTITUTION: A tube 2 is inserted into a blasted pipe 1. An outer diameter of the tube 2 corresponds to about 98% of an inner diameter of the pipe 1. Then, both ends of a position of 5cm from an end face of the inserted tube are blocked by locking clips 3. Thereafter, suction tubes 4 are mounted at both ends of the pipe 1. Each tube 4 is formed of an outer periphery 4A to be removably externally engaged with the end of the pipe 1 and a closing plate part 4C having a tubular suction port 4B. The outer periphery 4A of the tube 4 is externally engaged in a sealed state with both ends of the pipe 1 via packings. Then, a connecting tube of a vacuum pump is connected to the port 4B of the tube 4.