Angular, hinged expansion joints The angular expansion joints are used to compensate pipe expansion, particularly in pipe systems where there is change of the direction of the pipe axis. They are specially designed to absorb nearly any large amounts of movement and they do work in sets of at least two compensators in a hinged single plane piping system. The angular expansion joints are manufactured by BOA AG. In case of customer's interest, Metalloviotechniki can provide all the relevant documentation.