A heat exchanger comprises a shell comprising a hollow shell body and separate shell end members attached thereto. A number of tubes is disposed within the shell body which is sized to permit both ends of the tubes to project outwardly therefrom to facilitate access for attaching the tubes ends to respective tube header plates, after which time the shell end members are slid over the shell body towards the shell body ends for attachment to respective header plates. The heat exchanger can include an expansion element attached between a shell end member and the shell body, wherein the expansion element is positioned adjacent a slidable joint formed by an overlapping section of the shell body and shell end member. Together, the expansion element accommodates axial movement and the slidable joint carries vibration loads between the shell body and shell end member.