A tube seal for a pressure vessel includes a body, a seal groove and a tube retention collar. The body has an aperture formed therein for receiving a tube. The body also has an external surface and an internal surface. The seal groove is disposed in the external surface of the body for securing the body within an orifice formed in a wall of the pressure vessel. The tube retention collar is disposed on the internal surface of the body for engaging the tube and securing the tube within the tube seal. Pressure within the pressure vessel causes the body to deform about and engage the tube retention collar with the tube to secure the tube within the aperture.