A movement-constraining assembly for a fluid-conveying system comprises a tubular body adapted to be secured to a component coupling end of a component of the fluid-conveying system. A fluid-conveying tube has a tube coupling end adapted to be connected to the component of the fluid-conveying system and defining an inner passage for fluid to pass therethrough to or from the component, the tube having an interface at the tube coupling end. A blocking nut has an inner surface complementary to at least a surface of the interface of the tube to block rotation between the tube and the blocking nut, the blocking nut further comprising an outer surface complementary to a surface of the tubular body to block rotation between the blocking nut and the component, whereby the blocking nut blocks a rotation between the fluid-conveying tube and the component coupling end.