Granted Patent B2

US 12,240,066 · App. 17/427,568 · Granted Mar 4, 2025

Inventors: William Randal Bunker (Conroe, TX); Helna George (Houston, TX); Rajagopala N. Pillai (Pasadena, TX)

Assignee: National Oilwell Varco. L.P.

B23K9/23B23K9/0282C21D9/50B23K2103/05E21B17/042

Abstract

Claims (32)

1. A method of welding to join a high-strength low alloy steel first member to a stainless steel second member, the method comprising:

buttering a first joint surface on the b-strength low alloy steel first member, wherein buttering comprises:

preheating the first joint surface;

welding a border layer of weld material to the first joint surface; and

heat treating the border layer and the first joint surface after welding the border layer; and

forming a weld between the alloy steel first member and the stainless steel second member after heat treating the border layer and the first joint surface, the forming comprising:

preheating the border layer and preheating a second joint surface on the stainless steel second member; and

adding a body of weld material between the border layer and the second joint surface.

2. The method of claim 1 wherein adding a body of weld material comprises:

welding a plurality of passes of weld material between the border layer and the second joint surface; and

maintaining an interpass temperature of 177 degrees C. or less while welding the plurality of passes.

3. The method of claim 1 further comprising: maintain a welding heat input between 15 and 30 KJoule/inch while forming the weld between the first and second members.

4. The method of claim 1 further comprising: preheating the first and second members to 75+/−5 degrees F. prior to forming the weld between the first and second members.

5. The method of claim 1 wherein the second member is a precipitation-hardened (PH) stainless steel.

6. The method of claim 5 wherein the first member is tubular and the second member is tubular; and

wherein the plurality of passes of weld material are annular.

7. The method of claim 6 further comprising:

joining the first and second members at a threaded joint prior to welding the plurality of passes of weld material.

8. The method of claim 1 further comprising:

overlapping the first and second members prior to welding the plurality of passes of weld material.

9. The method of claim 8 wherein forming a weld between the first and second members further comprises: establishing a three-sided trough between first and second members;

wherein the trough includes the border layer on the first member and the second joint surface on the second member; and

wherein welding the plurality of passes of weld material is performed within the trough.

10. The method of claim 8 wherein the first member is tubular having a first weld-participating end and the second member is tubular having a second weld-participating end;

wherein a passageway extends through the first and second weld-participating ends;

wherein overlapping the first and second members includes aligning the first and second members along a centerline and includes an action selected from the following group of actions:

inserting a portion of the first weld-participating end inside a portion of the second weld-participating end; and

inserting a portion of the second weld-participating end inside a portion of the first weld-participating end;

wherein the method further comprises: removing an inner portion of the first weld-participating end or an inner portion of the second weld-participating end to expose the weld to the passageway.

11. The method of claim 1 further comprising:

performing an age hardening process for the weld formed between the first and second members;

wherein the age hardening process includes heating the weld to a temperature in the range of 482 to 621 degrees Celsius followed by air-cooling the weld.

Assignments (2)

Continuity (2)

References Cited (20)