Mandrel to be inserted into a liquid circulation pipe and associated positioning method

A mandrel to be inserted into a liquid circulation pipe, the mandrel comprising:

• a body having a longitudinal axis;
• a radially expandable annular sealing element comprising a centring arrangement and a closure arrangement for closing the centring arrangement, each arrangement being radially deployable relative to the body between a contracted configuration and a dilated configuration, the annular sealing element defining a continuous peripheral surface for application against the pipe and a continuous peripheral surface for application against the body when the centring arrangement and the closure arrangement are in the dilated configurations thereof;
• a radially expandable anchoring element which is at a longitudinal distance from the annular sealing arrangement, the anchoring element being displaceable between a refracted state and a deployed state in which the anchoring element delimits at least one axial pipe;
• and
• a sequencing arrangement capable of radially deploying the centring arrangement and the anchoring element before the closure arrangement;
• wherein the centring arrangement has an at least partly dilated configuration in which the centring arrangement defines at least one axial passage which extends through the annular sealing element, the closure arrangement radially closing the at least one axial passage as the closure arrangement is deployed from the contracted configuration thereof to the dilated configuration thereof, the anchoring element remaining in the deployed state thereof when the closure arrangement is radially deployed,
• wherein the body delimits a first radial expansion surface for radially expanding the centring arrangement and the closure arrangement, and a second radial expansion surface for radially expanding the anchoring arrangement which is longitudinally displaceable relative to the first radial expansion surface between
• a remote position in which the centring arrangement and the closure arrangement are in the contracted configurations thereof, the anchoring element being in the retracted state thereof,
• an intermediate centring position in which the centring arrangement is in the at least partly dilated configuration thereof and the anchoring arrangement is in an at least partly deployed state, the at least one axial passage and the at least one axial pipe being unobstructed at least in part, and
• a close closure position in which the closure arrangement is in the dilated configuration thereof to close the at least one axial passage defined by the centring arrangement,
• wherein the sequencing arrangement comprises a first member for resiliently urging the anchoring element towards the retracted state thereof, and a second member for resiliently urging the centring arrangement and the closure arrangement towards the contracted configurations thereof, and wherein the first urging member and the second urging member are initially prestressed and arranged in series between the first radial expansion surface and the second radial expansion surface, the first urging member having a level of stiffness and/or initial prestress which is different from a level of stiffness and/or initial prestress of the second urging member in order to enable continuous sequential deployment of the centring arrangement, the anchoring element, and then the closure arrangement.