A multi-port device for an air conditioning system comprising: a first tube having a flanged tube end, the flanged tube end of the first tube including a first sealing surface; a hollow main body including a first port receiving the tube end of the first tube, the first port having a base including a second sealing surface, said second sealing surface surrounding an aperture formed in the base of the first port; a first seal structure (10.1) disposed between the flanged tube end of the first tube and the main body; a first end plate receiving the first tube; and a first fastener engaging the first end plate and the main body; characterized in that the multi-port device further comprises a first collar having an outer wall with an opening formed therein, said opening receiving the first tube, the flanged tube end abutting the outer wall of the first collar, the first collar having an axially extending annular wall surrounding the opening of the first collar and the flanged tube end; the first sealing surface has a first sealing bead formed thereon; the first port receives the first collar and the base of the first port has an annular groove formed therein, said annular groove receiving the axially extending wall of the first collar, and the second sealing surface has a second sealing bead formed thereon radially inward from the annular groove of the first port; the first seal structure (10.1) is disposed radially inward from the axially extending wall of the first collar, the first seal structure (10.1) including a first seal portion produced from a plastically deformable metal or plastic material and having a free edge, and a second seal portion produced from an elastomer disposed on the free edge of the first seal portion; the first end plate abuts the outer wall of the first collar opposite the flanged tube end; the first fastener causes the first sealing bead of the first tube and the second sealing bead of the first port to plastically deform the first seal portion of the first seal structure and provide a primary seal between the first tube and the first port, and the first fastener causes the first sealing surface of the first tube and the second sealing surface of the first port to cooperate with the second seal portion of the first seal structure and provide a secondary seal between the first tube and the first port, wherein the primary seal and the secondary seal militate against a leakage of a fluid from the multi-port device; and the axial extent of the annular wall of the first collar is such that the main body and the first end plate are separated by a gap after the main body and the first end plate are fully engaged to form the primary seal and the secondary seal with the first seal structure. a first tube having a flanged tube end, the flanged tube end of the first tube including a first sealing surface; a hollow main body including a first port receiving the tube end of the first tube, the first port having a base including a second sealing surface, said second sealing surface surrounding an aperture formed in the base of the first port; a first seal structure (10.1) disposed between the flanged tube end of the first tube and the main body; a first end plate receiving the first tube; and a first fastener engaging the first end plate and the main body; characterized in that the multi-port device further comprises a first collar having an outer wall with an opening formed therein, said opening receiving the first tube, the flanged tube end abutting the outer wall of the first collar, the first collar having an axially extending annular wall surrounding the opening of the first collar and the flanged tube end; the first sealing surface has a first sealing bead formed thereon; the first port receives the first collar and the base of the first port has an annular groove formed therein, said annular groove receiving the axially extending wall of the first collar, and the second sealing surface has a second sealing bead formed thereon radially inward from the annular groove of the first port; the first seal structure (10.1) is disposed radially inward from the axially extending wall of the first collar, the first seal structure (10.1) including a first seal portion produced from a plastically deformable metal or plastic material and having a free edge, and a second seal portion produced from an elastomer disposed on the free edge of the first seal portion; the first end plate abuts the outer wall of the first collar opposite the flanged tube end; the first fastener causes the first sealing bead of the first tube and the second sealing bead of the first port to plastically deform the first seal portion of the first seal structure and provide a primary seal between the first tube and the first port, and the first fastener causes the first sealing surface of the first tube and the second sealing surface of the first port to cooperate with the second seal portion of the first seal structure and provide a secondary seal between the first tube and the first port, wherein the primary seal and the secondary seal militate against a leakage of a fluid from the multi-port device; and the axial extent of the annular wall of the first collar is such that the main body and the first end plate are separated by a gap after the main body and the first end plate are fully engaged to form the primary seal and the secondary seal with the first seal structure.