Seal for headed pin fastener member

Claim 1

A resilient seal for sealing between the head end of a headed pin fastener member and an apertured workpiece in which the pin is to be installed, which seal comprises: an outer annular part for sealing between the pin head and the workpiece around the aperture; and an inner annular part for fitting around the pin adjacent to the head; said inner annular part projecting beyond the thickness of the outer annular part in a direction perpendicular thereto and being tapered on the face thereof which is towards the outer annular part to provide wedging engagement between the pin and the aperture wall when the pin is inserted into the aperture so as to initially retain the pin in the aperture; said inner annular part also projecting on both sides of the outer annular part and being tapered on said face at both sides of said outer annular part so that the seal is substantially symmetrical whereby the seal can be assembled on the pin either way round; the seal further comprising a frangible weakened portion connecting said outer annular part to said inner annular part, said weakened portion being imperforate and continuous and having a lesser thickness than the said outer annular part, whereby said frangible weakened portion, when the pin head is drawn towards the workpiece, breaks and thereby enables the outer annular part to remain around the aperture as aforesaid whilst the inner annular part enters completely within the aperture.