Sealing plug

1. A sealing plug for sealing a hole in a wall, which sealing plug is insertable into the hole by access from only one side thereof, which sealing plug comprises:

a radially expandable body which is radially expandable by access thereto from only a first end thereof,

a sealing cap which covers a second end of the expandable body and extends therefrom along the exterior of the length of the expandable body, the sealing cap being of a material which is fluid resistant; and

retention-assisting means for retaining the sealing cap on the expandable body, wherein the retention-assisting means comprise an axial indentation of the first end of the expandable body that forms a local radial expansion of the expandable body into engagement with the sealing cap to retain the sealing cap on the expandable body;

wherein a radial cross-section of the sealing plug proximate to the first end of the expandable body is no greater than a radial cross-section of the sealing cap proximate to the second end of the expandable body;

whereby, when the sealing plug has been inserted in the hole and has been radially expanded so that at least part of the sealing cap adjacent the wall of the hole expands and engages therewith, the sealing cap is secured in the hole with the sealing cap sealing the expandable body against access thereto from outside the sealing cap.

2. A sealing plug as claimed in claim 1 , inserted into a hole as aforesaid, which sealing plug has been assembled by first inserting the sealing cap into the hole, and then inserting the expandable body into the sealing cap.

3. A sealing plug as claimed in claim 1 , which sealing plug has been assembled by inserting the expandable body into the sealing cap without, or before, inserting the sealing plug into the hole.

4. A sealing plug as claimed in claim 1 , in which the axial indentation is circular.

5. A sealing plug as claimed in claim 1 , in which the sealing cap is provided with at least one external circumferential projection, whereby to enhance engagement or sealing of the cap with the wall of the hole.

6. A sealing plug comprising:

a radially expandable body having a first end and a second end;

a stem protruding from the first end of the expandable body;

a head protruding from the second end of the expandable body, the head connected to the stem by a breakneck,

a sealing cap having a closed end that encloses the second end of the expandable body and the head, the sealing cap extending along the length of the expandable body to an open end configured to receive an annular spigot in contact with the first end of the expandable body, the sealing cap being fluid resistant; and

retention-assisting means for retaining the sealing cap on the expandable body, wherein the retention-assisting means comprise an axial indentation of the first end of the expandable body that forms a local radial expansion of the expandable body into engagement with the sealing cap to retain the sealing cap on the expandable body;

wherein the expandable body is configured such that an axial force applied to the stem causes the expandable body to radially expand within the sealing cap from compression between the head and the spigot;

where the sealing plug is bound by a cylinder having a diameter no greater than a diameter of a radial cross-section of the sealing cap adjacent the second end of the expandable body.

7. The sealing plug as claimed in claim 6 , where the axial indentation is a circular axial indentation.

8. The sealing plug as claimed in claim 6 , where the sealing cap further comprises:

a plurality of circumferential ribs, and

where the radial cross-section of the sealing cap adjacent the second end of the expandable body is the radial cross-section of one of the plurality of circumferential ribs adjacent the second end of the expandable body.

9. The sealing plug as claimed in claim 6 , wherein the expandable body has a hardness less than a hardness of the sealing cap.