PATC Cuts Heavy Wall Tubes for Sampling and Rebuilding Feedwater Heaters:

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PATC Cuts Heavy Wall Tubes for Sampling and
Rebuilding Feedwater Heaters

• By Dan Bina and Joe KrauseAmerican Power
  Services Inc.2788 Circleport DriveErlanger, Ky
  41018
• 1-800-535-6649 24/7

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It had been impossible to internally cut
heavy wall feedwater heater tubes for tube
samples or for rebuilding heaters.
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Tubes PATC can cut
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New power supply and controlsprovides no damage
to the adjacent tubes
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Eddy current tests show no OD metal loss in the
adjacent tubes.
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PATC Operation

• PATC uses a 6 pulse SCR configuration to rectify
  a 480 VAC, 3 phase input to 150 VDC for plasma
  cutting. The amperage is set by the potentiometer
  between 5 and 50 amps. Automatic regulation of
  the arc results in a smooth, steady DC current at
  the torch.

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PATC Portable Equipment
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Joe Krause, APS Code Welder, demonstrating a 12
foot cut of 5/8 OD X 0.083 wall 304 Stainless
FW Tube
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The arc is controlled to penetrate the OD of the
tube and go no further.
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New controls

• Doss
• Spatter
• Size of the arc
• Speed of the cut
• Gas pressure
• Results in no damage to the adjacent tubes
• or to the tube sheet hole as tubes are pulled
  through the tube sheet.

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Dross and Spatter from SS Cut
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• H35 (65 argon/35 hydrogen) gas cylinder
• New variable amperage power supply
• PATC electronic control case
• Trigger drive unit with remote controls
• PATC flexible wand
• PATC body and cutting tip.

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American Power Services Feedwater Heater
Services

• PATC
• Hydraulic tube extraction
• Eddy current testing other NDE
• Individual tube hydro testing
• On site troubleshooting inspection
• Failure cause analysis with repair upgrades
• Removal of mechanical plugs and weld patches in
  tube sheets
• Tube sheet repairs and restoration.
• Mechanical Explosive tube plugging and tube
  staking
• Robotic on line tube plugging
• Tube cleaning
• Tube expansion hydraulic, explosive and
  mechanical
• Installing tube inlet ferrules, metal sleeves,
  full length liners
• Feedwater heater rebuilding and repair
• Heater redesign to avoid past failures,
  mechanical thermal design
• Expediting heater fabrication on site or shop
• Field Machining, Code Welding Heater
  installation

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PATC Conclusion

• Tubes of any metal alloy, stainless, carbon
  steel, monel, titanium, inconel, can be cut at
  any distance into the tube from the tube sheet
  face for tube sampling.
• PATC can save a week or more on rebuilding
  heaters on site or in shop.
• Tubes from ½ to 2 ½, .028 to 1.50 wall have
  been cut successfully.
• Adjacent tubes are not damaged.