Abstract: A flange assembly for connecting a pipe to a tank at an access opening through a wall thereof includes an externally threaded cylindrical portion having an internal annular recess, a compressible sealing member received in the recess, a cap threaded into the portion and engaging the sealing member, and a flange portion with a shallow annular recess of greater diameter than that of the access opening which carries an O-ring for sealing between the wall and the flange.