Method of repairing in situ a pipe or tank of thermo-fusible material, and device for implementing this method

A method for repairing in situ a pipe or tank having internal damage at or next to an inner surface in which the internal damage underlies an external surface, wherein the pipe or tank is made of thermo-fusible material, the method comprising:

• detachably installing an electric heating element on the pipe or tank to cover an area of the external surface of the pipe or tank where the internal damage underlies;
• and
• providing a power supply device to supply electric energy to the electric heating element to increase a local temperature at the area of the external surface where the internal damage underlies to melt the thermo-fusible material at the external surface where the internal damage underlies, and to maintain a temperature at the inner surface of the pipe or tank lower than a softening temperature of the thermo-fusible material, wherein the temperature is maintained in the inner surface of the pipe or tank where the internal damage is located at an annealing temperature which is below a softening point of the thermo-fusible material of the pipe or tank.