Abstract: A break-out washer assembly for facilitating undoing a connection between interengaged complementally threaded elements. The assembly comprises a washer which tapers radially inwardly and is made of a ductile material and a pair of annuli which straddle the washer, the annuli being complementally shaped to the washer and being made of a relatively harder material. The assembly is interposed between opposing shoulders of the threaded elements which are tightened to extrude the washer and impose a hoop stress on it. The connection is undone by breaking the washer at a chosen circumferential position.