PURPOSE: To prevent the crack generation of a lining member and weld zone by forming a recessed stepping part at a nonuniform sectional part and arranging the clad steel of the combination of the same material with a base metal at the stepping part.

CONSTITUTION: In case of arranging a lining member at the nonuniform sectional part of a tube plate 1, etc., the clad steel of the lining cladding member 10 of a high corrosion resistance of a Ti, etc., and the lining base metal 11 of the same material as that of a tube plate 1 is employed for the lining member. The stepping in a recessed shape is executed in advance at the tube plate 1 side and the clad steel is installed at the stepping part. In this case, the cladding member 4 and joint member 12 of the same material are welded by arranging at the both end parts of the lining cladding member 10. The lining base metal 11 is welded to the tube plate 1. A gap 9 becomes about zero due to the base metal 11 being worked in the same shape as that of the tube plate 1. The stress generation of the lining member and a weld zone 3 is reduced and the crack generation is prevented because the base metal 11 of the clad steel is formed by the same material as that of the tube plate 1.