Remy 21-May-11 (17:47) post about a similar experience.
The tube failures were traced to a heat-treating step in the last stage of fabrication. The tubes were placed on refractory bricks in an annealing furnace to keep them a few inches above the furnace floor. Unfortunately, a metallurgical imperfection occurred everywhere the brick contacted the tube, thus compromising its mechanical integrity!
Now you have heard... the rest of the story!
Regards, Phil Corso
The tube failures were traced to a heat-treating step in the last stage of fabrication. The tubes were placed on refractory bricks in an annealing furnace to keep them a few inches above the furnace floor. Unfortunately, a metallurgical imperfection occurred everywhere the brick contacted the tube, thus compromising its mechanical integrity!
Now you have heard... the rest of the story!
Regards, Phil Corso