Tank connection assembly, in particular for a fuel-operated vehicle heater, comprising a connection pipe to be passed through a tank opening in a tank wall and extending in the direction of a pipe longitudinal axis (L), and a fastening assembly on the connection pipe for fixing to the tank wall in the region of the tank opening , wherein the fastening assembly comprises: - a first clamping element fixed to the connection pipe , - a second clamping element , wherein the second clamping element is engaged with or engageable with the first clamping element such that rotation of the second clamping element relative to the first clamping element about the pipe longitudinal axis causes movement of the second clamping element relative to the first clamping element in the direction of the pipe longitudinal axis (L), characterized in that the fastening assembly further comprises: - an expansion element fixed to the connection pipe at an axial distance from the first clamping element at least in the direction away from the first clamping element for support on a first side of a tank wall , - an abutment element arranged axially movable between the first clamping element and the expansion element , supportable or supported via the second clamping element with respect to the first clamping element axially in a direction away from the expansion element , with a first sealing portion for providing a tight seal with respect to an outer circumferential surface of the connection pipe and a second sealing region for providing a tight seal with respect to a second side of the tank wall facing away from the first side . - a first clamping element fixed to the connection pipe , - a second clamping element , wherein the second clamping element is engaged with or engageable with the first clamping element such that rotation of the second clamping element relative to the first clamping element about the pipe longitudinal axis causes movement of the second clamping element relative to the first clamping element in the direction of the pipe longitudinal axis (L), characterized in that the fastening assembly further comprises: - an expansion element fixed to the connection pipe at an axial distance from the first clamping element at least in the direction away from the first clamping element for support on a first side of a tank wall , - an abutment element arranged axially movable between the first clamping element and the expansion element , supportable or supported via the second clamping element with respect to the first clamping element axially in a direction away from the expansion element , with a first sealing portion for providing a tight seal with respect to an outer circumferential surface of the connection pipe and a second sealing region for providing a tight seal with respect to a second side of the tank wall facing away from the first side . - an expansion element fixed to the connection pipe at an axial distance from the first clamping element at least in the direction away from the first clamping element for support on a first side of a tank wall , - an abutment element arranged axially movable between the first clamping element and the expansion element , supportable or supported via the second clamping element with respect to the first clamping element axially in a direction away from the expansion element , with a first sealing portion for providing a tight seal with respect to an outer circumferential surface of the connection pipe and a second sealing region for providing a tight seal with respect to a second side of the tank wall facing away from the first side . <EOS>