To make it possible to fit tubular rubber moldings easily to an object to which the moldings are fitted without being influenced by the blend composition and shape of the tubular rubber moldings by swelling the moldings with a smaller inner diameter than the outer diameter of the object using a solvent and fitting the moldings to the object.

Tubular silicone rubber moldings 1 are soaked in a solvent isooctane for 8 or more hours to swell the rubber with the help of this solvent. Because of the seepage of the solvent into the polymer chain of the rubber, the inner diameter of the tubular rubber moldings 1 becomes larger and soft. In addition, the inner diameter part is slippery on account of the solvent which moistens the inner diameter part. In this case, the inner diameter of the tubular rubber moldings 1 is about 43mm and the outer diameter is about 67mm. The tubular rubber moldings 1 which are swollen are passed through two pipes 2, 3 with an outer diameter of 35mm, and the center of the tubular rubber moldings 1 is matched with a pipe connecting part 4 and is left as it is. Further, the solvent is blown off by heating and then the pipe 2, 3 are connected together.