Sleeve fastening system

A sleeve fastening system for fastening to a joist pierced with a hole and to receive two pipes, the sleeve fastening system comprising:

• a cylinder of which each end is configured to receive a pipe by fitting, wherein a wall of the cylinder has cut into the wall at least one tunnel that is sealed with respect to an inside of the cylinder, wherein the cylinder is configured to be fitted into a hole in the joist;
• a flange as one with the cylinder and extending around the cylinder, wherein each tunnel has a first and second openings that emerge outside the wall of the cylinder and on either side of the flange, wherein the flange has a bearing face to bear against the joist and a free face opposite;
• and
• for each tunnel, a holding system having a link, a shoe as one with a first end of the link and a locking system, wherein the link is housed in the tunnel such that the shoe is blocked at the first opening that is on a side of the free face and such that the second end of the link exits via the second opening on a side of the bearing face and wherein the locking system has a connector that attaches to the second end of the link and a bearing surface to come to bear against the joist.