Search

EP-4735200-A1 - METHOD OF WELDING METAL PLATES

EP4735200A1EP 4735200 A1EP4735200 A1EP 4735200A1EP-4735200-A1

Abstract

There is provided a method of welding metal plates (22) comprising: i) undertaking friction stir welding using a friction stir welding machine (26) along a lower edge of a joint welding line (40) between adjoining metal plates (22, 22') weighing in excess of 50 tonnes so as to create a root pass weld (42) along the joint welding line (40), the friction stir welding machine (26) disposed beneath the plates (22, 22') so as to weld in an overhead position; and ii) after friction stir welding, undertaking electron beam welding using an electron beam gun (28) along an upper edge of the joint welding line (40) so as to create a welded seam between adjoining plates, the electron beam gun (28) disposed above the plates. At least three adjoining metal plates are welded together and formed into a tube with a diameter in excess of 11m.

Inventors

  • PUNSHON, Christopher

Assignees

  • Aquasium Technology Limited

Dates

Publication Date
20260506
Application Date
20240530

Claims (12)

  1. 1. A method of welding metal plates comprising: i) undertaking friction stir welding using a friction stir welding machine along a lower edge of a joint welding line between adjoining metal plates weighing in excess of 50 tonnes so as to create a root pass weld along the joint welding line, the friction stir welding machine disposed beneath the plates so as to weld in an overhead position; and ii) after friction stir welding, undertaking electron beam welding using an electron beam gun along an upper edge of the joint welding line so as to create a welded seam between adjoining plates, the electron beam gun disposed above the plates.
  2. 2. A method according to Claim 1, wherein each metal plate has dimensions of each around 10m long and around 4m wide, with a wall thickness of between 90 to 130mm.
  3. 3. A method according to Claim 1 or Claim 2, wherein at least three adjoining metal plates are welded together and formed into a tube with a diameter in excess of 1 Im.
  4. 4. A method according to any of the preceding claims, further comprising replacing a welding head of the friction stir welding machine with a milling head and milling along the joint welding line before friction stir welding takes place.
  5. 5. A method according to any of the preceding claims, wherein the root pass weld is 12 to 20mm in depth.
  6. 6. A method according to any of the preceding claims, wherein the electron beam welding takes place within a vacuum.
  7. 7. A method according to any of the preceding claims, wherein the friction stir welding takes place within a vacuum.
  8. 8. A method according to any of the preceding claims, wherein the electron beam welding and the friction stir welding take place within a common evacuatable housing.
  9. 9. A method according to any of Claims 1 to 7, wherein the metal plates are moveable along a conveyor and the friction stir welding machine and the electron beam gun are spaced apart with respect to the direction of travel of the metal plates, the friction stir welding machine upstream of the electron beam gun.
  10. 10. A method according to any of the preceding claims, wherein the metal plates are be formed from one or more of the following: steel, C-Mn structural steel, steel alloys, Nickel, Titanium, Aluminium, Nickel alloys, Titanium alloys, Aluminium alloys.
  11. 11. A metal tube made in accordance with the method of any of Claims 1 to 10.
  12. 12. A metal tube according to Claim 11 having a diameter in excess of 11m.

Description

Title: Method of Welding Metal Plates Field of the Invention This invention relates to a method of welding metal plates, and in particular large scale metal plates such as used to form pressure vessels, reactors and wind turbines. Background to the Invention Welding structures for pressure vessels, reactors and wind turbines is difficult due to the size and weight of the metal plates that need to be welded together. Offshore wind energy structures are typically made out of a plurality of hollow metal cylinders or cans formed from metal plate up to 130mm thick. Typically two metal plates are rolled to each make half a cylinder and then the two rolled plates are welded together to form a complete cylinder. The size and weight of the plates makes processing extremely difficult and time-consuming. Given the increasing requirements for ever larger diameter cylinders for offshore monopiles, pressure vessels and reactors, and the maximum size of metal plates available, there is a need to join more than two metal plates together to gain a cylinder with a circumference of around 40m when welded. However using existing techniques weld quality is difficult to maintain when the joined plates are rolled ready for welding into a cylinder. Summary of the Invention In accordance with one aspect of the present invention, there is provided a method of welding metal plates comprising: i) undertaking friction stir welding using a friction stir welding machine along a lower edge of a joint welding line between adjoining metal plates weighing in excess of 50 tonnes, and preferably above 80 tonnes, so as to create a root pass weld along the joint welding line, the friction stir welding machine disposed beneath the plates so as to weld in an overhead position; and ii) after friction stir welding, undertaking electron beam welding using an electron beam gun along an upper edge of the joint welding line so as to create a welded seam between adjoining plates, the electron beam gun disposed above the plates. By creating a root pass weld before electron beam welding, it is possible to weld vertical edges of adjoining metal plates using electron beam welding without compromising the quality of the electron beam weld. The resulting weld allows conjoined plates to be rolled into a hollow cylindrical shape ready for final welding without the welded seams failing. Preferably each metal plate has dimensions of each around 10m long and around 4m wide, with a wall thickness of between 90 to 130mm, and desirably at least three adjoining metal plates are welded together for forming into a tube with a diameter in excess of 11m. The method may further comprise replacing a welding head of the friction stir welding machine with a milling head and milling along the joint welding line before friction stir welding takes place. This avoids the need to move the heavy metal plates between milling and friction stir welding, such that it only forms part of the weld depth, the metal plates typically having a thickness of 90 to 130mm. Preferably the root pass weld is 12 to 20mm in depth. The electron beam welding desirably takes place within a vacuum. The friction stir welding may take place within a vacuum to prevent oxidation of the friction stir welding tool. The electron beam welding and the friction stir welding may take place within a common evacuatable housing. The metal plates are preferably supported on a conveyor, such as a roller conveyor, so as to be moveable with respect to the friction stir welding machine and the electron beam gun. The friction stir welding machine and the electron beam gun are preferably spaced apart with respect to a direction of travel of the metal plates, such that the friction stir welding machine is upstream of the electron beam gun and thus any portion of the metal plates passes the friction stir welding machine before reaching the electron beam gun. This allows two seams to be processed in tandem, a root pass weld being formed for one joint weld line whilst electron beam welding takes place of a joint weld line with a root pass weld. The metal plates may be formed from steel such as C-Mn structural steel, steel alloys or any other metallic material requiring welding, such as Nickel, Titanium, Aluminium and their alloys. In accordance with another aspect of the invention, there is provided a metal tube made in accordance with the method as aforesaid, and preferably a metal tube having a diameter in excess of 1 Im. The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of an electron beam assembly for welding a hollow cylinder formed from two metal plates; Figure 2 is a perspective view of a first embodiment of a welding arrangement to undertake a method in accordance with the invention; Figure 3 is a schematic diagram to explain creation of a root pass weld; Figure 4 is a photograph of a root pass weld; Figure 5 is a schematic diagr