Packerhead machines for making concrete pipes are disclosed by Gourlie et al in U.S. Pat. No. 3,262,175 and Fosse et al in U.S. Pat. No. 3,551,968. These machines use outer forms and pallets in conjunction with packerheads to make concrete pipes. The packerheads are rotatably mounted on upright shafts and move upwardly in outer forms or jackets to make cylindrical concrete walls. The jackets containing the concrete pipes are transported to a curing area where the jackets are stripped from the pipes. The pipes are cured on pallets. The jackets are elongated cylindrical walls that are held in a closed position with releasable latch structures. Some jackets are three-piece arcuate segment construction as shown in U.S. Pat. No. 2,015,001. Separate lock structure is used to hold the pallets in assembled relation with the bottom ends of the jackets.