The single-use expansion coupler (also known as one-time compensator or EKO) is a component which will be welded into the preinsulated pipeline. During the heating period alterations of the pipe length will occur, which will be reliably compensated by this system. Due to the welding of the EKO-guiding pipes, the prestressing of the pipeline will be fixed ater the expansion compensation will be completed.

Single-use expansion couplers will be used in case where the maximum of pipe laying length [L_max] cannot be kept or/and natural expansion elements will be not possible due to lack of space.