Patent Number: 
Section: claims

1. A method for working on a defective heating element of a pressuriser comprising a tank elongated along a longitudinal axis and elongate heating elements extending within the tank, and at least one spacer plate through which the heating elements pass and which is capable of maintaining a transverse spacing between the heating elements, the method comprising:cutting at least one spacer plate around the heating element so as to detach the heating element from the spacer plate; and thenextracting the heating element from the tank. 2. The method as recited in claim 1 wherein the heating element is extracted in one single piece. 3. The method as recited in claim 1 wherein the heating element is extracted by at least one of pulling on an upper end portion of the heating element and by pushing on a lower end portion of the heating element, with a lower end portion extending through a wall of the tank and out to the exterior of the tank. 4. The method as recited in claim 1 wherein the or each spacer plate is cut by an electrical discharge cutting tool comprising an electrical discharge head and an electrical discharge electrode. 5. The method as recited in claim 4 wherein the electrode is slipped around the heating element and then the electrode is lowered in a manner so as to cut the or each spacer plate around the heating element. 6. The method as recited in claim 4 wherein the cutting tool is fastened onto a spacer plate by positioning the cutting tool while using as reference points at least one of the heating elements adjacent to the heating element to be extracted and water circulation openings for the circulation of water through the or each spacer plate. 7. The method as recited in claim 4 wherein the electrode is tubular. 8. The method as recited in claim 1 wherein the heating element is detached from a through passage sleeve of the heating element through a wall of the tank on the exterior of the tank. 9. The method as recited in claim 4 wherein a replacement heating element is positioned in place at the location of the extracted heating element. 10. The method as recited in claim 9 wherein the heating element is fixed to the spacer plate by a section of plate that is attached and fastened to the spacer plate and includes a through opening for passage of the replacement heating element. 11. The method as recited in claim 10 wherein the section of plate is positioned by using as reference points the heating elements adjacent to at least one of the replacement heating element and the openings for circulation of water through the or each spacer plate. 12. The method as recited in claim 1 wherein the extracted heating element is disposed in a handling container inside the tank prior to extracting the heating element from the tank.