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Boiler Tube Machining: Work Scope

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.

Close tolerance machining of the tubes was necessary for the orbital tube welding process. The mandatory J-bevel dimension was a 20-degree bevel with a .062" radius, a land extension of .032" +/- .005" and a land thickness of .062" +/- .005". The counterbores had to match within .005" as well.

The work scope for Project 1:
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 1 shift a day, 8-10 hrs per shift. Avg. 123 tubes per day / 61 per technician.

The work scope for Project 2:
Machine a total of 2016 tube ends that were 1.750" OD. All tubes were hung in the boiler and access for machining was the challenge. To complete the machining, all of the tubes had to be pried apart in place to allow access for the machine.

Solution: 2016 tubes in the boiler - Tubes were machined by 8 MTI technicians in 24 shifts, working 2 shifts a day, 10 hrs per shift. Avg. 84 tubes per shift / 21 per technician.

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