Connectors incorporating retainers and stopper mechanisms

A connector has a pivot shaft extending axially between a pair of flanges of a connector body. The retainer includes a bearing portion at one end, with an expandable insertion slot engageable with the pivot shaft such that the retainer pivots about the pivot shaft. The retainer has a temporary engagement position where a pipe can be inserted and removed and a regular engagement position where a bulge portion of the pipe is engaged preventing the pipe from being removed. A stopper claw formed on an opening edge of the insertion slot contacts with a contact surface, preventing the connector body from pivoting beyond the temporary engagement position. This prevents a condition where the retainer further pivots past the temporary engagement position which can cause the insertion slot to expand and the retainer separating from the pivot shaft.