Abstract: A pipe lap joint is disclosed with an improved sealing zone structure in the overlap region of the pipes. The sealing zone comprises a serpentine slot extending from the end of the outer pipe to an inner end-wall of the slot. The joint comprises a band clamp with a clamping band which covers the sealing zone including the inner end of the slot. One sidewall of the slot defines an inwardly protruding tooth and the other sidewall defines another inwardly protruding tooth with a narrow passage between the teeth which is provided by rounded corners on the teeth. The slot also includes a bulbous end-wall which facilitates uniform collapse of the sealing zone. When the band clamp is tightened, the sealing zone is collapsed such that the two teeth engage each other and seal the serpentine slot against leakage.