In 2007 and 2008, MTI was contracted to perform all machining and welding in conjunction with replacing a steam chest at a fossil plant in Wisconsin. All welding was performed with the orbital GTAW machine welding process. Prior to installation on site, MTI manually welded each side of the steam chest to stop valve.
Customer Case Study – The challenge with machining the 590 header tubes is that 360 of the header tubes required the bevels to be on a 20-degree angle and 3/16th offset from the center line of the through-hole in the header. The 360 offset tubes required us to bore out the existing tube perpendicular to the bore of the pipe with one operation and then utilize our stub tube machine to complete the process with the offset weld prep. All of this was performed with limited overhead clearances. The project was completed in 12 days.
Customer Case Study – MTI Power has the ability to weld with a Narrow Groove or a Conventional Groove Orbital Machine GTAW process and has successfully completed numerous hot reheat pipe replacement projects.
The pipe material was P-22 (2. chrome / 1-moly) and was either 38″ OD x 1.8″ wt or 29″ OD x 1.6″ wt. The welds were in the 2-G (vertical) or 5-G (horizontal) positions, with some in limited access environments.
At the completion of the job, our customer stated: "I was very satisfied with the performance of your organization during the installation/welding of the Hot Reheat Piping System. Your welding staff performed their scope of work accident-free and in a quality manner. Your supervisor and his group were able to work in a very congested area. They were able to quickly deal with magnetized weld joints at each Reheat Intercept Valve and produce very clean radiographs."
Customer Case Study – MTI Power Services completed two boiler tube machining projects for the same customer at two different power plants that were under construction. Our services were required because all of the tubes in question were supplied with 20-degree bevels on them instead of J-bevels that were essential for the orbital welding process.
Machine a total of 1972 tube ends that were 1.500″ OD. All tubes were located on the ground with easy access and were not positioned in the boiler.
Solution: 1972 tubes on the ground – Tubes were machined by 2 MTI technicians in 16 shifts, working one shift a day, 8-10 hrs per shift. Avg. 123 tubes per day / 61 per technician.
Machine a total of 2016 tube ends that were 1.750″ OD. All tubes were hung in the boiler, and access to machining was the challenge. To complete the machining, all of the tubes had to be pried apart in place to allow access to the machine.
Solution: 2016 tubes in the boiler – Tubes were machined by 8 MTI technicians in 24 shifts, working two shifts a day, 10 hrs per shift. Avg. 84 tubes per shift / 21 per technician.