One solution to economically and safely extend the life of a pressure pipe is to insert a flexible  pipe or a  flexible liner inside the old pipe using  a method known as pull through.  Benefits  of this method include:  no trenching,  project completed in days not months, simple installation  process requiring  minimum personnel and equipment, no internal corrosion , no adhesion to old pipe and a continuous  pipe  system of few hundred metres  or few  kilometres in length meaning fewer joints and excavations.