Method for installing an elongated element into a duct , comprising the steps of: - inserting the elongated element into the duct through a pressure chamber located at an entry of the duct , by applying a driving force ( F a ) to the elongated element, resulting in an effective pushing force ( F 2eff ) downstream the pressure chamber , - introducing pressurized fluid into the duct at a first pressure, through the pressure chamber , wherein after an instant when said elongated element has entered the duct and before an instant when said elongated element reaches a final position into the duct , the method comprises the steps of: - monitoring at least fluid pressure ( p d ) into said duct at the entry of the duct or in the pressure chamber, and said driving force ( F a ), - calculating an axial outward pressure force ( F i ) applied to the elongated element, - reducing said fluid pressure ( p d ) to a predetermined value lower than the first pressure, in relation to said driving force ( F a ), wherein the driving force ( F a ) is applied upstream an entry of the elongated element into the pressure chamber so as to push the elongated element into the pressure chamber with a external pushing force ( F 2 ), and wherein the fluid pressure ( p d ) is reduced if the fluid pressure ( p d ) results in the calculated axial outward pressure force applied to the elongated element susceptible to be equal or greater than the external pushing force ( F 2 ). - inserting the elongated element into the duct through a pressure chamber located at an entry of the duct , by applying a driving force ( F a ) to the elongated element, resulting in an effective pushing force ( F 2eff ) downstream the pressure chamber , - introducing pressurized fluid into the duct at a first pressure, through the pressure chamber , wherein after an instant when said elongated element has entered the duct and before an instant when said elongated element reaches a final position into the duct , the method comprises the steps of: - monitoring at least fluid pressure ( p d ) into said duct at the entry of the duct or in the pressure chamber, and said driving force ( F a ), - calculating an axial outward pressure force ( F i ) applied to the elongated element, - reducing said fluid pressure ( p d ) to a predetermined value lower than the first pressure, in relation to said driving force ( F a ), - monitoring at least fluid pressure ( p d ) into said duct at the entry of the duct or in the pressure chamber, and said driving force ( F a ), - calculating an axial outward pressure force ( F i ) applied to the elongated element, - reducing said fluid pressure ( p d ) to a predetermined value lower than the first pressure, in relation to said driving force ( F a ), wherein the driving force ( F a ) is applied upstream an entry of the elongated element into the pressure chamber so as to push the elongated element into the pressure chamber with a external pushing force ( F 2 ), and wherein the fluid pressure ( p d ) is reduced if the fluid pressure ( p d ) results in the calculated axial outward pressure force applied to the elongated element susceptible to be equal or greater than the external pushing force ( F 2 ). <EOS>