Abstract: The present application relates to a method for pressurizing the inner flow space of an underwater flexible pipe intended for transporting hydrocarbons, comprising the following steps: a) providing a flexible pipe comprising a reinforcing layer made up of a short-pitch winding of at least one metal wire with noncontiguous turns around a thermoplastic polymer sheath defining an inner space, then b) filling the inner space of the flexible pipe with an oil, then c) increasing the inner pressure Pi of the flexible pipe to at least 10 MPa, the inner pressure being exerted by said oil, then d?) maintaining the inner pressure Pi of the flexible pipe at a pressure of at least 10 MPa for a time D of at least one minute, characterized in that said oil has a kinematic viscosity at 40° C., measured according to the ASTM D445 standard, of more than 10 mm2/s. This method makes it possible to reduce, or even prevent, the appearance of cavitation and crazing on the polymer sheath.

Abstract: The present application relates to a method for pressurizing the inner flow space of an underwater flexible pipe intended for transporting hydrocarbons, comprising the following steps: a) providing a flexible pipe comprising a reinforcing layer made up of a short-pitch winding of at least one metal wire with noncontiguous turns around a thermoplastic polymer sheath defining an inner space, then b) filling the inner space of the flexible pipe with an oil, then c) increasing the inner pressure Pi of the flexible pipe to at least 10 MPa, the inner pressure being exerted by said oil, then d?) maintaining the inner pressure Pi of the flexible pipe at a pressure of at least 10 MPa for a time D of at least one minute, characterized in that said oil has a kinematic viscosity at 40° C., measured according to the ASTM D445 standard, of more than 10 mm2/s. This method makes it possible to reduce, or even prevent, the appearance of cavitation and crazing on the polymer sheath.