1. SF6 Leak Repair
Case Study ConEd West 49th Street GIS Jonathan Brengel, ConEd Liisa Colby, The Colt Group

2. Agenda Station Overview SF6 Emissions Summary Leak Identification
Repair History
Alternative Solutions
Repair Cost
Issues
Moving Forward
The Leak Repair Process
Other SF6 Repair Examples

3. Station Overview

6. Station Overview
West 49th Street Substation reduces voltage from 345 kV to 138 kV
Five 345 kV feeders
Two from Sprain Brook Substation
Two from East 13th Street Substation
One inter-utility feeder from Public Service Electric and Gas Company
Eleven 138 kV feeders from the station supply W 42nd St., W 50th St., W 65th St. and Astor Substations
Gas Insulated Switchgear (GIS) at the station was put into service in 1978
No design requirements to control leakage were in place in 1978
Fifteen SF6 insulated 345 kV and 138 kV bus sections
Five autotransformers
Ten 345 kV circuit breakers

9. SF6 Historical Emissions
2,049 lbs. of SF6 Emissions from West 49th Street in
Accounts for ~17% of total SF6 emitted for entire company in 2015
*Gas call data improvements were implemented during 2014 resulting in enhanced data accuracy during the 2nd half of 2014 onward
Areas of greatest concern
Transformer 3 secondary bus, Bus Section 3, Transformer 5 secondary bus
49th Street Substation SF6 Annual Emissions Summary
2014
2015 YTD
Total SSO SF6 Emissions (lbs)
15,901
12,682
Total 49th Street (lbs)
*1,576
2,049
% of Total SSO Emissions
9.91%
16.20%

10. SF6 Historical Emissions
Transformer 3 Secondary Bus Section
24 gas calls in 2014
For each gas call a mechanic attempted to find a leak
Average leak identification time of 4 hours x $85/man-hour x 24 gas calls = $8,160
366 lbs. SF6 emitted 2015
27 clamps, 8 bypasses and 9 patches on bus work currently
*Gas call data improvements were implemented during 2014 resulting in enhanced data accuracy during the 2nd half of 2014 onward
TR3 SF6 Annual Emissions Summary
*2014
2015
Total TR3 Secondary Bus (lbs)
421
366
Total Bus Section 3 (lbs)
263
217
Total TR5 Secondary Bus Section (lbs) 88
249

11.  Leak Identification & Sampling Techniques Minimize number of samples
ZERO Purge SF6 Analysis
Previously emitted 2 lbs per sample
lbs released per year
New DILO SF6 gas analyzers
Improved tool for leak detection
FLIR GF306 SF6 Camera  11

12. 49th Street Substation SF6 Repair Summary
SF6 Leak Repair Status 94
100 35
49th Street Substation SF6 Repair Summary
Total clamps installed
(including on bypasses)
Total bypasses
Total patches
Total Active leaks
Clamp on leaking bypass in Transformer 3 Secondary Bus
Clamp on leaking flange in Bus Section 7
Welded patch on secondary CCPD

13. Colt Clamp Temporary Repairs
$263,000 in O&M spent in 2014 on clamps
$324,000 spent in O&M already through September of 2015
Estimating $162,000 to be spent on clamps/repairs during remainder of year
~$4,000 to $15,000 per clamp
Concern with added weight, structural integrity, bus failure, etc.
Aluminum clamps may also be used - Lighter weight but more expensive
Moving forward, all clamps require supports
2 year Warranty

14. Examples: Colt Clamp Repairs

16. Permanent Repairs Eliminate centralized gas fill system
Remove clamps on leaking welds and re-weld/repair (outage required)
Currently planning to remove 5 clamps and repair welds on TR5 secondary during fall outage
NDE testing on patches/welds that aren’t clamped to identify possible future leak areas
Replace temporary bypass piping clamps with stainless tubing and DILO self-sealing fittings

17. Equipment Replacement
Install a circuit breaker on each 138 kV feeder leg (2 circuit breakers, disconnect switches, all buswork)
Estimated at $2.3 million per each 138 kV section (equipment cost only)
Maintain reliability advantages
Replace a 345 kV Bus Section (circuit breaker, potential transformer, disconnect/ground switches, bus, LCC, adapter flanges and structures)
Estimated at $1.75 million per bus section (equipment cost only)
~14 to 16 month delivery and installation

18. West 49th Street 2015 Annual SF6 O&M Costs
Additional Costs
West 49th Street 2015 Annual SF6 O&M Costs
Item
Total Cost
Clamp Installation
$486,000
SF6 Gas Added ($8.50/lb)
$19,920
Daily Leak Locating/Repairs
$180,000
Split TR Secondary Alarm Points
$74,000
Install Supports on Existing Clamps
$42,000
Fall Outage Leak Repairs
$173,000
Chem Lab - Gas Sampling/Outage Support
$29,400
TOTAL PROJECTED COST
$1,004,320
*Project annual costs based on actual spent YTD

19. Issues Lack of O&M funding
No long range plans to replace equipment and no plan for added capacity
Limited availability for outages

20. Moving Forward How do we help meet future goals?
15,000 lbs. – 2015 (equivalent to 7% of nameplate)
14,000 lbs. – 2016 proposed goal
13,000 lbs. – 2017 proposed goal
Continue to leverage capital programs
Circuit Breaker Reliability Program
SF6 GIS Bus Overhauls
AGS Retirements
SF6 Peer Management Team
SSO/EH&S-Air/Chem Lab/Engineering/TLC
Monthly meetings to keep lines of communication open
Maintain focus, identify and work through issues together

21. The Leak Repair Process

23. Options for dealing with leaks:
Let it leak If oil is getting out, air and moisture are getting in
Re-gasket or replace Cost, outage time, resources required
In-house Repair (Epoxy) Not always effective
Use Outside Repair Specialists An alternative worth considering

24. No need to drain the oil or gas or depressurize
Benefits of Online Leak Repair for HV App
No need to drain the oil or gas or depressurize
Many repairs can be made under pressure – energized
The sealant is not an epoxy – it’s flexible and easily removed

25. Epoxy – can’t be easily removed Do-it-yourself Kit
Common Misconceptions of Leak Repair
It’s a band-aid
What is temporary?
Epoxy – can’t be easily removed
Do-it-yourself Kit
Concerns about the sealant

26. A Proven Process 15,323 jobs completed since 2002 6,286 Flanges
5,691 Valve packings 1,045 Custom clamps & enclosures
875 Drain plugs
287 Cover plates
91 Miscellaneous Tap changer flanges
24 CTs
987 re-pumps over twelve years or 6.4%. A 93.6 success rate

27. The History of Online Leak Repair

28. Leak Sealing Today
Pressures up to 7,500 psig Temperatures from Cryogenic to 1800 F

29. After 20+ Years of Experience

30. Oil Leak Flange Repair using “Drill & Tap” injection

31. About The Sealant Independent Lab Report Results:
Dissolved Gas in Oil (DGA)
Dielectric strength
Minus 40 degrees C/F – 40 degrees C/F
Sealant is NOT an epoxy - It’s flexible and easily removed.

32. Manufacturer Warranty TC Flange Repair
Sealant injected via Injectable Bolts
Repair made with unit in service

33. Custom Clamps & Enclosures Thread Leak on Valve (Bar Clamp)33

34. Alliant Energy Eddyville Substation 69 kv SF6 Breaker Eddyville, Iowa
SF6 Leak Repair Example
Alliant Energy Eddyville Substation 69 kv SF6 Breaker Eddyville, Iowa

38. Client options Let it leak. Not an option, environmental concern
Re-gasket. Time to take the breaker out of service was the primary issue. Would require 5 days of down time, loss of transmission and $20, in costs
Leak Repair – Installing custom enclosure and injecting sealant. Determined the optimal solution
Justification: Reduced downtime for critical apparatus. Just 1 day of down time and $20, to fix all leaking components Savings = 4 days of transmission

45. SF6 Circuit Breaker - Casting Leak.

46. SF6 Circuit Breaker - Casting Leak
SF6 Leaks
SF6 Circuit Breaker - Casting Leak

48. Ongoing Research….

49. Clamp Removal

50. Sealant Removal

51. Thank you