Self-retaining plug and compatible socket

A mechanical plug having a longitudinal axis defining forward and rearward axial directions, inward and outward radial directions, and clockwise and counter-clockwise circumferential directions as viewed in the forward direction, comprising:

• a plug body having opposed forward and rearward ends, wherein the forward end has a generally flat sealing surface facing in the forward direction and a generally circular elastomeric seal affixed on the sealing surface generally concentric with the longitudinal axis, and wherein at least a portion of the plug body has an outer circumferential surface adapted for engagement by at least one of a wrench and a socket for rotation of the plug about the longitudinal axis;
• a protuberance extending from the forward end of the plug body generally concentric with the longitudinal axis, the protuberance having a first section contiguous with the plug body, and a second section having a hub portion contiguous with the first section and a plurality of generally evenly spaced arms extending outward from the hub portion, each arm having a clockwise radial edge, a counter-clockwise radial edge and an underside surface facing the sealing surface of the plug body, a major portion of the underside surface of each arm being generally flat and generally parallel to the sealing surface;
• a respective rearwardly projecting nub located on the respective underside surface of each respective arm of the plurality of arms proximate the clockwise radial edge of each respective arm, each nub having a ramp on a clockwise side thereof terminating rearwardly in an apex and a wall on a counter-clockwise side thereof extending generally in the radial and axial directions from the apex to the major portion of the underside surface;
• a nipple extending from the rearward end of the plug body;
• and
• a through-hole extending through the nipple and transitioning within the plug body into one or more branches, wherein each branch terminates in a respective opening on the sealing surface of the plug body and is non-concentric with the longitudinal axis.

A fastening system, comprising:

• (a) a plug having a longitudinal axis defining forward and rearward axial directions, inward and outward radial directions, and clockwise and counter-clockwise circumferential directions as viewed in the forward direction, the plug comprising:
• a plug body having opposed forward and rearward ends wherein the forward end has a generally flat sealing surface facing in the forward direction;
• a protuberance extending from the forward end of the plug body generally concentric with the longitudinal axis, the protuberance having a first section contiguous with the plug body, and a second section having a hub portion contiguous with the first section and a plurality of generally evenly spaced arms extending outward from the hub portion, each arm having a clockwise radial edge, a counter-clockwise radial edge and an underside surface facing the sealing surface of the plug body, a major portion of the underside surface of each arm being generally flat and generally parallel to the sealing surface;
• a respective rearwardly projecting nub located on the respective underside surface of each respective arm of the plurality of arms proximate the clockwise radial edge of each respective arm, each nub having a ramp on a clockwise side thereof terminating rearwardly in an apex and a wall on a counter-clockwise side thereof extending generally in the radial and axial directions from the apex to the major portion of the underside surface;
• a nipple extending from the rearward end of the plug body;
• and
• a through-hole extending through the nipple and terminating in one or more openings on the sealing surface of the plug body;
• and
• (b) a socket formed in a thin-walled part, wherein the socket includes an aperture through the thin-walled part bounded by a rim of the thin-walled part thereabout, the aperture having one of a generally circular perimeter and a generally regular polygonal perimeter, and a plurality of generally evenly spaced tabs of the thin-walled part extending radially inward from the perimeter, wherein the number of tabs is a positive integer multiple of the number of arms.