Methods and apparatus for securing an autoclave bag to a composite fixture are disclosed. An example apparatus includes a flange sealing device including a forward flange at a first end and an aft flange at a second end, and a composite fixture including a forward groove to locate and seal with the forward flange of the flange sealing device to affix an autoclave bag, an aft groove to locate and seal with the aft flange of the flange sealing device to affix the autoclave bag, and an aft locating ring to position the autoclave bag.