Westinghouse SG Tube Sleeve Designs and Installation. Jesse Baron, PE Principal Engineer

Transcription

1 Westinghouse SG Tube Sleeve Designs and Installation Jesse Baron, PE Principal Engineer 1

2 Overview What is a Tube Sleeve? Why Use a Sleeve? History of the Westinghouse SG Tube Sleeve Tube Sleeve Design Alloy 800 Tube Sleeve Installation Process Sleeve In-service NDE Inspections Licensing of a Tube Sleeve Recent Westinghouse Experience Tube Sleeve Horizons 2

3 What is a Sleeve? Why Use a Sleeve? What is a Tube Sleeve? A smaller diameter tube section bridging a defect in the straight leg of the parent tube. Secured to the parent tube at each end of the sleeve. Manufactured with corrosion resistant material. Allows a tube that otherwise would be plugged to remain in service. Why use a Tube Sleeve? Plant is either near, or projected to be near, the SG tube plugging limit. Significant increasing trend in tube plugging. Plugging any more tubes equates to steam pressure and power generation loss. 3

4 History of the Westinghouse SG Tube Sleeve Westinghouse and ABB-CE Welded SG Tube Sleeves First generation SG tube sleeves Westinghouse hard rolled tubesheet joint with a Brazed upper joint Hydraulically expanded upper joint with a hard roll in the middle Hydraulically expanded upper joint and laser welded ABB-CE hard rolled tubesheet joint with hydraulic upper expansions followed by TIG welding Relatively time consuming installations with complicated setup requirements and specialized personnel qualifications Welding and heat treatment parameters highly variable Leak free 4

5 History of the SG Tube Sleeve Hydraulically Expanded Alloy 800 Sleeves Differential thermal expansion Thermal expansion coefficient of Alloy 800 > Alloy 600 Sleeve-to-tube joint tightens as temperature increases Result is high contact pressure between sleeve and tube Low residual stress in Parent Tube (<0.5% strain) No welding = no heat treatment required Installed sleeve can be inspected in-service with conventional eddy current techniques Leak limiting 5

6 History of the SG Tube Sleeve Product offering reviews discontinued the welded sleeve Alloy 800 hydraulically expanded tube sleeve remains primary Westinghouse offering Development and application timeline for Alloy 800 tube sleeve: Development by Westinghouse at Mannheim, Germany office First Field Installation of Alloy 800 Sleeve at Tihange Development continued for application in United States NRC approval of License Amendment Request First United States domestic installation at Calvert Cliffs Nearly 1,400 Alloy 800 Hydraulic Sleeves Installed in the United States and 400 in Sweden. Approximately 17,500 more installed in Belgium, Slovenia, Brazil and South Korea 6

7 Alloy 800 Tube Sleeve Design Tubesheet Expansion Transition Sleeve 25-inch long sleeve section Spans defect at top of tubesheet elevation Post installation tube access ~90%-93% of original Six Hydraulic Expansions at Upper End Rolled Joint at Lower End centered at Tubesheet Mid-Plane 7

8 Alloy 800 Tube Sleeve Design Tube Support Structure Sleeve 20-inch long Sleeve Spans Defects at Tube Support Post-Installation Tube Access ~93%-96% of original Six Hydraulic Expansions at Upper and Lower Ends 8

9 Alloy 800 Tube Sleeve Installation Process Minimal Number of Steps for Installation 1. Tube End Marking (Optional) 2. Sleeve Insertion 3. Sleeve Upper/Lower Expansion (Tube Support Sleeve) 4. Sleeve Upper Expansion and Lower Torque Rolling (Tubesheet Transition Zone Sleeve) 5. Eddy Current for Expansion Confirmation and Baseline Positioning 9

10 Alloy 800 Tube Sleeve Installation Process Pressure, psi (x10-4 ) Elastic deformation Plastic deformation Sleeve to Tube Contact Sleeve-Tube Maximum Deformation Residual deformation Time, s 10

11 Alloy 800 Tube Sleeve Installation Process 11

12 Alloy 800 Tube Sleeve Installation Process Hard Roll Torque Mandrel 12 Hard Roll Tubesheet Joint

13 Tube Sleeve In-Service NDE Inspections Tubesheet Sleeve on HL Side SG Tube Typically Bobbin inspected from cold leg up to sleeve Tubesheet Sleeve RPC inspection of Sleeve ± 3 13

14 Tube Sleeve In-Service NDE Inspections Tube Support Sleeve on HL Side SG Tube Bobbin inspection from cold leg up to top of sleeve Bobbin inspection from hot leg up to bottom of sleeve Tube Support Sleeve RPC inspection of Sleeve ± 3 14

15 Tube Sleeve In-Service NDE Inspections Tubesheet and Tube Support Sleeve SG Tube Bobbin inspection from cold leg up to top of tube support sleeve RPC inspection of the straight tube section between the sleeves from hot leg Tubesheet and Tube Support Sleeve RPC inspection of Sleeve + 3 above tube support sleeve 15

16 Licensing of a Tube Sleeve SG tube sleeves are a primary-to-secondary pressure boundary repair that require a licensing basis amendment ASME Code rules provided in Section XI IWA-4720 Westinghouse has developed topical reports providing the technical basis to support license amendment requests: WCAP P for Alloy 800 Sleeves in 3/4 Alloy 600 Tubes WCAP P for Alloy 800 Sleeves in 7/8 Alloy 600 Tubes WCAP P for Alloy 800 Sleeves in 11/16 Alloy 600 Tubes An approximate total of twelve sleeved tubes is hydraulically equivalent to just one plugged tube 16

17 Recent Westinghouse Sleeve Experience Removed Tube Pre-Conditioning Process Qualified per ASME Section XI One less process step improves production rate Less equipment and lower personnel contamination potential Removal of Nickel Band in Lower Joint Improves inspectability of Parent Tube behind sleeve Removes concern with sleeve inspection Working to Make Sleeve Installations Economically Viable In Small Numbers Significant equipment reduction Reduce mobilization costs and specialty crew qualifications Increase similarity to mechanical tube plugging iteration 17

18 Tube Sleeve Horizons Tube sleeves had a heyday in the US during the late 1980s and 1990s Many of the sleeved SGs have been replaced Currently not a large number of tube sleeves in service in US Will the degradation trends of Alloy 600TT tubing make for a second heyday? SGs with Alloy 600TT tubes are aging Historical trends have a way of coming back around Need to monitor degradation and make long term projections to decide whether tube sleeving is a practical solution 18

19 Conclusions Westinghouse Alloy 800 SG tube sleeves are an established and accepted technology. Sleeve installations have been performed around the world. Extensive field experience globally. Safe and effective repair option that allows otherwise pluggable tubes to remain in service. Tube sleeves can contribute to SG operating longevity while maintaining safe and efficient operation. With an unclear horizon, tube sleeves should be a consideration for plants with Alloy 600 tubing. 19

20 QUESTIONS? The scientific man does not aim at an immediate result. He does not expect that his advanced ideas will be readily taken up. His work is like that of the planter -- for the future. His duty is to lay the foundation for those who are to come, and point the way. - Nikola Tesla, Physicist, Engineer and Inventor 20