A needle assembly (1, 100) for an injection device comprising a needle cannula (10, 10), a hub (30, 130) comprising skirt portion (40, 140) and a central portion (60, 60). The skirt portion (40, 140) is having an internal surface (43, 143) adapted for connection to an injection device, wherein the skirt portion (40, 140) is having an open proximal end (41, 141) adapted to be sealed off by a sealing member (90, 190). The hub (30, 130) is having a distal end (42, 142) closed by the central portion (60, 160), wherein the central portion (60, 160) is adapted to receive the cannula (10, 110). The internal surface (43, 143) of the skirt portion (40, 140) comprises a connecting member, a cap portion (80, 180) for covering the distal end (12, 112) of the cannula (10, 110), a frangible zone (89, 189). The cap portion (80, 180) can be turned from an initial mode, wherein the frangible zone (89, 189) connects the cannula cap portion (80, 180) and the hub (30, 130), to a broken mode, wherein the frangible zone (89, 189) is broken, and wherein the cannula cap portion (80, 180) and the hub (30, 130) can be separated from each other. The sealing member (90, 190) is permeable to a sterilizing agent, and thereby adapted to enable sterilization of an internal space (5, 105).
