The present invention provides an injection adapter for a spout of a fluid container used in sealing and/or insulation of electrical cable joints. The injection adapter comprises: a fluid conduit having an inlet neck with an inlet opening that is adapted to be inserted into the spout; one or more clipping members arranged on an outer perimeter of the fluid conduit and oriented with free ends towards the inlet neck that are adapted to lock the spout, wherein the free end of each clipping member is adapted to be deflected outwards in a radial direction when mechanical force is applied in said free end along a non-radial direction for unlocking the respective clipping member from the spout. The invention also provides an injection valve with the injection adapter and a valve member for preventing back-flow of fluid.