Abstract: An open end of a standard pipe fitting is enlarged in diameter to coaxially receive an O-ring and a retainer having a cylindrical surface. A plurality of locking teeth project from the cylindrical surface and are engageable with both the inner surface of the fitting and an outer surface of a pipe end inserted coaxially into the fitting open end. Each of the locking teeth have oppositely disposed edges facing obliquely inwardly and outwardly to engage both the pipe end and the fitting and resisting motion of the pipe end relatively to the fitting. In an alternate embodiment, a first plurality of teeth each have an edge facing obliquely inwardly of the fitting to engage the pipe end and resist motion tending to withdraw the pipe end from the fitting. A second plurality of teeth each have an edge facing obliquely outwardly of the fitting and resist motion tending to withdraw the retainer from the fitting.