Method for repairing heat recovery steam generator tube-to-header damage
AssigneeElectric Power Research Institute, Inc.
InventorsDavid Wayne Gandy, Greg Frederick, Kent Coleman
Life of this patent
Estimating the term…
Abstract
A method for repairing a heat recovery steam generator (HSRG) header to tube attachment damage, includes providing an access window in the header opposite the damaged header to tube attachment location; removing the header to tube attachment damage; inserting a tapered stub tube into a header penetration centered axially immediately over the tube; effecting a profile weld between the header and the tapered stub tube at the header penetration from the inside surface of the header; welding the tapered stub tube to the existing tube through the header inside diameter; welding shut the access window; and completing a post weld heat treatment of all the welds.
Claims13
A method for repairing header to tube attachment damage, comprising:
- providing an access window in a header opposite the attachment damage location;
- removing the attachment damage;
- inserting a tapered stub tube into a header penetration centered axially immediately over the tube;
- effecting a profile weld between the header and the tapered stub tube at the header penetration from the inside surface of the header;
- welding the tapered stub tube to the existing tube through the header inside diameter;
- welding shut the header access window;
- and
- completing a post weld heat treatment of all welds;
- wherein said providing an access window in the header opposite the damaged header to tube attachment location comprises:
- mounting a-base plate to the header to position tooling, about 180 degrees away and centered axially along the header from the header to tube attachment damage location;
- mounting an EDM assembly to the base plate;
- removing a plug from the header, about 180 degrees from the attachment damage location, that is greater in diameter than the stub tube;
- and
- realigning the base plate with a centering alignment plug and centering ring.
A method for repairing header to tube attachment damage, comprising:
- providing an access window in a header opposite the attachment damage location;
- removing the attachment damage;
- inserting a tapered stub tube into a header penetration centered axially immediately over the tube;
- effecting a profile weld between the header and the tapered stub tube at the header penetration from the inside surface of the header;
- welding the tapered stub tube to the existing tube through the header inside diameter;
- welding shut the header access window;
- and
- completing a post weld heat treatment of all welds;
- wherein said inserting the tapered stub tube into the header penetration comprises:
- removing a cutting assembly from a base plate mounted to the header;
- slipping the stub tube and an insertion tool over a primary mandrel inserted into the tube;
- aligning the stub tube contour with the header contour;
- and
- securing the stub tube in the header.
Dependencies are inferred from the claim text.