A system is provided for passing matter in a flow passage of an oil and/or gas drilling or production installation, in particular for passing trash or drill cuttings in a drilling fluid return line. The system includes at least two valves arranged in series in said passage; and a control device configured to selectively or sequentially actuate said at least two valves, such that the material is allowed to pass said at least two valves in the passage. A method is also provided for passing trash or drill cuttings in a drilling fluid return line.