Method of and apparatus for controlling a weld penetration profile with application of shielding gas in an inner region of a workpiece

1. A method for controlling a weld penetration profile on a workpiece having an outer region and an inner region comprising the steps of:

placing seals oriented proximate open conduit ends of the workpiece to form a predominantly sealed inner region that prevents shielding gas from escaping through the conduit ends, wherein gas may only escape a pre-welded abutment of the workpiece;

applying energy to the outer region of the workpiece with a welder to produce a weld pool;

penetrating the workpiece such that the weld pool spans between the outer region and the inner region; and

applying a shielding gas to the inner region at a pressure that provides a force that limits weld penetration;

measuring the pressure of the shielding gas within the inner region;

comparing a measured pressure with a predetermined range of acceptable pressures; and

adjusting the pressure of shielding gas within the inner region ( 338 ) to be within the range of acceptable pressures if the pressure measured falls outside the range of acceptable pressures to maintain a constant pressure of shielding gas within the inner region.

2. The method for controlling a weld penetration profile of claim 1 , wherein the pressure of shielding gas is between about 0.01 psi and 1.0 psi.

3. The method for controlling a weld penetration profile of claim 1 , wherein the pressure of shielding gas is between about 0.03 psi and 0.30 psi.

4. The method for controlling a weld penetration profile of claim 1 , wherein the pressure of shielding gas is between about 0.04 psi and 0.245 psi.

5. The method for controlling a weld penetration profile of claim 1 , comprising the step of:

providing a filler metal to the weld pool of metal.

6. The method for controlling a weld penetration profile of claim 1 , wherein the weld is autogenous.

7. The method for controlling a weld penetration profile of claim 1 , wherein the weld penetration is prevented from exceeding approximately 0.0625 inches past a surface defining the inner region.

8. The method for controlling a weld penetration profile of claim 1 , wherein the weld penetration is prevented from exceeding past a surface defining the inner region by a distance that is approximately 10% of the thickness of the workpiece.

9. An apparatus ( 300 ) for controlling a weld penetration profile on a workpiece ( 306 ) having an outer region ( 336 ) and an inner region ( 338 ), comprising:

a welder ( 302 ) configured to create a weld joint ( 334 ) from the outer region ( 336 ) of the workpiece ( 306 ), wherein the weld joint ( 334 ) penetrates from the outer region ( 336 ) of the workpiece ( 306 ) to the inner region ( 338 ) of the workpiece ( 306 );

seals oriented proximate open conduit ends of the workpiece to form a predominantly sealed inner region that prevents shielding gas from escaping through the conduit ends, wherein gas may only escape a pre-welded abutment of the workpiece;

a gas supply ( 314 ) in fluid communication with the inner region ( 338 ) configured to provide a shielding gas to the inner region ( 338 ) of the workpiece ( 306 ), wherein a pressure of the shielding gas provides a force that limits weld penetration; and

a pressure gauge ( 332 ) in communication with the inner region ( 338 ), wherein the pressure gauge ( 332 ) is configured to measure the pressure of the shielding gas present in the inner region ( 338 );

a valve ( 328 ) in fluid communication with the inner region ( 338 ) configured to adjust the shielding gas pressure within the inner region ( 338 ) by controlling the amount of shield gas provided by the gas supply ( 314 );

a system electronics ( 400 ) in communication with both the pressure gauge ( 332 ) and the valve ( 328 ), wherein the system electronics ( 400 ) is configured to receive a pressure signal from the pressure gauge ( 332 ) and adjust the valve ( 328 ) accordingly so to maintain a constant pressure within the inner region ( 338 ).

10. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the predetermined pressure range is between about 0.01 psi and 1.0 psi.

11. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the predetermined pressure range is between about 0.03 psi and 0.30 psi.

12. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the predetermined pressure range is between about 0.04 psi and 0.245 psi.

13. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the welder ( 302 ) comprises a gas tungsten arc welding (GTAW) apparatus.

14. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the welder ( 302 ) comprises a shielded metal arc welding (SMAW) apparatus.

15. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the welder ( 302 ) comprises a gas metal arc welding (GMAW) apparatus.

16. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the welder ( 302 ) comprises at least one of a laser beam welder, electroslag welder, magnetic pulse welder, and friction stir welder.

17. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the shielding gas comprises argon.

18. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the shielding gas comprises at least one of nitrogen, helium, carbon dioxide, oxygen, hydrogen, nitric oxide, sulfur hexafluoride, and dichlorodifluoromethane.

19. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the workpiece ( 306 ) comprises a steel alloy.

20. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the workpiece ( 306 ) comprises at least one of steel, stainless steel, aluminum, magnesium, copper, platinum, nickel, carbon, chromium, cobalt, niobium, tungsten, vanadium, zirconium, and molybdenum.

21. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the workpiece ( 306 ) comprises a conduit.

22. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the workpiece ( 306 ) comprises a flange.

23. The apparatus ( 300 ) for controlling a weld penetration of claim 9 , wherein the workpiece ( 306 ) comprises at least a part of a flowmeter ( 5 ).

24. A method for controlling a weld penetration profile on a portion of a flowmeter having an outer region and an inner region, comprising the steps of:

placing seals oriented proximate open conduit ends of the workpiece to form a predominantly sealed inner region that prevents shielding gas from escaping through the conduit ends, wherein gas may only escape a pre-welded abutment of the workpiece;

applying energy with a welder to the outer region of the portion of the flowmeter to produce a weld pool;

penetrating the portion of the flowmeter such that the weld pool spans between the outer region and the inner region;

applying a shielding gas to the inner region at a pressure that provides a force that limits weld penetration;

maintaining an approximately constant pressure of shielding gas within the inner region, wherein the pressure of shielding gas is between about 0.01 psi and 2.0 psi;

measuring the pressure of the shielding gas within the inner region to generate a measured pressure;

comparing the measured pressure with a predetermined range of acceptable pressures; and

adjusting the pressure of shielding gas within the inner region to be constant.

25. The method for controlling a weld penetration profile on a portion of a flowmeter of claim 24 , wherein the pressure of the shielding gas is between about 0.03 psi and 0.30 psi.

26. The method for controlling a weld penetration profile on a portion of a flowmeter of claim 24 , wherein the weld penetration is prevented from exceeding approximately 0.0625 inches past a surface defining the inner region.

27. The method for controlling a weld penetration profile on a portion of a flowmeter of claim 24 , wherein the weld penetration is prevented from exceeding past a surface defining the inner region by a distance that is approximately 10% of the thickness of the workpiece.