HRSG tube to header leaks frequently occur in hard to access areas.  The standard technique for making this repair has been for the service crew to cut their way in to the repair site and then weld their way back out.  The other alternative is to plug the tube.

We offer a proprietary process where the repair is remotely welded after a window has been machined in the opposite side of the header.  Through that window we machine away the compromised sections of the header and tube.  A stub tube is then inserted reconnecting the tube to the header.

The stub tube is welded to both the original tube and to the header.  Finally the original coupon is welded back, closing the header.  This procedure results in a permanent repair.

This innovative method offers a number of benefits.  No good tubes are cut in order to gain access to the weld site.  The repaired tube is left in service, not plugged.  This is a quick procedure; most tubes can be repaired within one shift.  And finally, as this is a semi-automatic welding system, results will be consistent from one repair to the next.

Steps 1 & 2 - Place Saddle on header and align. - Place EDM on Saddle and execute penetration hole cut. Remove the cored header coupon and store for future reinstallation.
Steps 3 & 4 - Remove EDM Head, install Alignment Tool and readjust Saddle as required. Then, install tube dams (foreign object protection). - Place EDM Fin-Tube Severance Head and commence Fin-Tube Severance. Upon completion, remove tool and exchange dams.
Step 5 - Remove EDM Fin-Tube Severance Head and install Fin-Tube Machining Tool. Cut Fin-Tube to desired length.
Step 6 - Position the Stub-Tube onto the Autogenous I.D. Weld Tool and install the assembly onto the Saddle. Perform Fin-Tube to Stub-Tube weld. Remove weld tool when complete.
Step 7 - Install the Stub-Tube to Header Full Function Cold Wire Feed GTAW Weld Head and perform Stub-Tube to Header I.D. Weld. Remove tool when complete.
Step 8 - Inspect, remove tube dams, and then reinstall header access hole coupon.

Please note: The above illustrated process is protected by
US Patent Application #11/364,604 and additional patents are in process.