Abstract: A flange alignment tool for facilitating connection of large diameter, flanged pipe sections. The tool is inserted in the corresponding bolt openings of the adjacent flanges and expanded to cause the bolt openings to come into precise alignment all around the abutting flanges to be joined together. The tool comprises a plurality of internally tapered partial sleeve sections, each having a constant external diameter. The sleeve sections are resiliently biased against a pair of tapered expanding mandrels which are threadably received on a long, central bolt member which is turned to cause the mandrels to move together, expanding the alignment tool in the bolt openings. After the permanent fastening bolts are secured in the aligned bolt openings, the tool is contracted and removed from the bolt openings, and a permanent fastening bolt replaces it.