The authors propose two improved algorithms for solving the problems of optimal design and control of pipeline nets. One of them is a general model (P), in which the governing system of equations (EQ) is equivalent to an unconstrained minimization problem (P), while the other model (P') corresponds to the optimal design and control for the degraded nets of nonlinear pipelines. The proposed algorithms not only extend the scope of selection for the iterative matrix \(B\), but also diminish the number of subprograms by one, or more precisely, from 3 to 2. Moreover, they prove the convergence of their algorithms under certain conditions.