Guest102023
Materials
- Feb 11, 2010
- 1,523
I would like to know what is 'best practice' for repair of a single (or possibly several) tube-to-header welds.
I recently observed from a distance (I was only involved in the tube F/A) as a contractor proceeded to preheat only the end of the 12"Ø header where the repair was to be done, and with a propane torch. The repaired tube happened to be the last one, middle row; CSEF tube to conventional 2¼Cr-Mo header.
Firstly, I did not agree with oxyfuel preheating and temperature crayon monitoring - I thought now that we are in the 3rd millenium it would have been electric pads with TC control.
Second, I had doubts about thermal stresses resulting from PWHT only locally. I should think you would want to heat things up symmetrically.
Any experiences/practices anybody can share?
I recently observed from a distance (I was only involved in the tube F/A) as a contractor proceeded to preheat only the end of the 12"Ø header where the repair was to be done, and with a propane torch. The repaired tube happened to be the last one, middle row; CSEF tube to conventional 2¼Cr-Mo header.
Firstly, I did not agree with oxyfuel preheating and temperature crayon monitoring - I thought now that we are in the 3rd millenium it would have been electric pads with TC control.
Second, I had doubts about thermal stresses resulting from PWHT only locally. I should think you would want to heat things up symmetrically.
Any experiences/practices anybody can share?