Abstract: A plug and socket value assembly including three main components is disclosed. The valve assembly includes a body or insert having an inlet and outlet, a closure element having a resilient seal which isolates the inlet from the outlet, and a connector plug having a fluid passageway which, when inserted into the body, displaces the closure element and opens the valve to allow fluid flow. The seal comprises a resiliently deformable end part which is urged against the body. This forces the body into the casing opening of the article in which the valve assembly is disposed and firmly secures the valve assembly in the casing.