Case History on Submerged-Arc Welding
by Paul Ipolito
(New York State)
This seems like an appropriate time to share a success story regarding submerged-arc welding. We are producing 23 pieces of fluid-mixing equipment for a Central American mineral processing project.
Part of our equipment includes a 7.5 inch diameter Inconel 625 bar with a 2.5 inch thick flange welded to one end of the bar. Normally when processing a quantity of one or two of these type shafts in our shop we would use SMAW.
We allocated approximately 25 shop hours per shaft to complete the weldment. We felt there had to be a better way to expedite these parts through our shop. We decided to weld a test plate using Special Metals Inconel 625 wire (3/32" diameter) and Special Metals NT-100 submerged-arc flux.
The procedure testing went well and we started production with SAW (Submerged Arc Welding). We are now able to weld a complete shaft in 8 hours! We are also required to apply 100% UT examination to these shafts and I am pleased to report all have passed inspection with no apparent indications.
I believe that despite our best intentions, we would not have had the same UT (Ultrasound Testing) results with the SMAW (Shielded Metal Arc Welding) process. We were also able to have one welder produce the required shafts to maintain production flow. We assigned two welders who were scheduled to work on the shafts to other items associated with this project.