There are numerous configurations of flexible and expansion joints available to the design engineer. They include bellows joints, flexible hoses, bolted-mechanical couplings, and ball joints. In 1989 EBAA Iron, Inc. introduced the FLEX-TEND® joint (FT) flexible expansion joint product into the US market. Constructed of ductile iron, the product is comprised of two ball joints joined by an expansion joint. For the first time one product was available to protect pipelines and pipeline connections from differential movement resulting from seismic activity and soil expansion/contraction in areas of poor soil support, frost heave, and transitions from stable to unstable areas.