A pipe connecting structure for a heat exchanger includes a header tank having a connect opening; a connector block having a passage configured to connect a pipe thereto; an adapter configured to connect the header tank and connector block to each other, the adapter having a first cylindrical part to be connected to the connect opening of the header tank, a second cylindrical part to be connected to the passage of the connector block, and a flange radially extending between the first and second cylindrical parts and being interposed between joint areas of the header tank and connector block; and a brazing material applied to a joint area of the flange to be joined to the header tank and a joint area of the flange to be joined to the connector block, so as to join the header tank and connector block together by brazing.
A pipe joint 1 comprises a fitting 10 connected with a hose 2, a flange 20 pressingly holding the fitting 10 inserted into a through hole 21 toward a block 3, a bolt 30 for fixing tightly the flange 20 to the block 3, a metal seal 40 having "C" cross section so as to seal a joined portion of a communication passage 11 and a connection opening 3a externally, and a first and a second O-rings 50, 60 so as to seal a contact portion of the fitting 10 and the block 3. A projecting portion 24 is formed on a lower face 23 of the flange 20, the projection portion 24 is formed at an area opposite to an area where the insertion hole 21 is formed with respect to a center axis of the through hole 21, the project portion 24 projects from other portion of the flange towards the block 3. A tip of the fitting 10 inserted into the through hole 21 projects towards the block 3 from the lower face 23 of the flange 20.
