Katie Harkless Project Manager-Replacement Washington Gas

Transcription

1 Cast Iron Renewal Techniqueses Katie Harkless Project Manager-Replacement Washington Gas

2 Washington Gas Overview Serve D.C. and adjoining areas in MD and VA Approximately 1.2M customers 22 gate stations, 2 peak shaving plants, and 1 storage field 2

3 WG Cast Iron Piping DC 428 miles MD- 75 miles VA 17 Miles Total cast iron = 520 miles Replace 5-6 miles annually

4 WG Cast Iron Renewal Techniques Liners Cured-in-place liner U-liner Joint sealants Internal joint sealants External joint sealants Insertion Plastic insertion

5 WG Cast Iron Renewal Techniques Cured- In-Place Liner C d I Pl Li Cured-In-Place Liners WG primarily uses on 12 and larger diameters due to thicker pipe wall Example project Anacostia river rehab project Used liner because wanted to directionally drill but couldn t obtain permit from National Park Service. Remediated 1800 (2-900 lengths)

6 Cured-In-Place Anacostia River Rehab Project Cured-in-place process Disconnect pipe Clean pipe Pre-lining inspection (CCTV) Lining process Post-lining inspection Pressure test Activate the line

7 Anacostia River Rehab Project Background of the Project 16-inch cast iron pipes leaking under river Winter 2009 Replace Option Drill new lines Install new lines through Anacostia Park Complete line replacement Rehabilitation Options Insertion Lining selected as best option

8 River Crossing Location

9 Project Design Concerns Concerns related to depressurizing i of the main and possible water infiltration Double lining considered, first lining to stop water infiltration & second dfor gas carrier Obtaining Permits from Parks Dept Working from Vault Side without dismantling the vault Environmental issues related to dewatering of park side pit

10 Pipeline Inspection Depressurizing i of fthe First tleg of ftwin 16-Inch 16I main Phase I Consideration was given to live camera inspect while simultaneously lowering the gas pressure to witness any water infiltration ti WGL opted not to live camera inspect and depressurized first leg of twin main The pipeline after depressurizing was almost completely dry with only the first two cast iron joints weeping a little water

11 Cured-in-place Lining Technology

12 Pipeline Before Cleaning to Final Product

13 Camera Inspection Working from the park side of the project, the first camera inspection of the pipeline revealed a clean main, except for the last 100ft or so before the drip The debris found was sand like, the amount of debris became greater the closer it came to the drip valve Debris Drip

14 Blast Hose from Vault Side

15 Pipeline Cleaning

16 Cleaning Process

17 Filling the Drip Valve Drip filling Methodology Inserted 2-14-Inch pigs into the bottom of the drip Inserted 90ft of 2-Inch PVC pipe Camera Mixed and poured adhesive into 2-Inch pipe and fill drip (27 Cans used) Observed process through camera 2-14 Pigs

18 Lining Process

19 Lining Process Concrete Vault Sub Station Side Pressure Drum Direction of Lining Drip filled with 2-Pigs & Adhesive Park Side With Steel Sheeting Box

20 Lining Process

21 Clearance Concerns Important: For every two feet (2ft) of additional cover, top of main, The cut-out section of space between the mains MUST increase By one additional foot (1ft) for example, a pipe with 6 feet (6ft) of Cover requires a 7 foot (7ft) cut-out 2-Foot 6ft Section 4FT cover Section to be Lined Utility Requirement 1-Foot

22 Clearance Requirements Side View Pressure Drum 4ft Approx 40ft Long Including Trucks Direction Of Lining 1ft Approx 10-12ft12ft Long

23 Consequences of Misalignment Misalignment at the inversion point creates unsupported liner within the rehabilitated pipeline and a Spot Repair is required after curing Unsupported liner liner Unsupported liner Not enough Space to properly Align hose fitting

24 Loading the Lining

25 Inversion Cone Being Connected to Liner

26 Lining

27 Line Complete Valve Cast iron Joint Half/Pig to support Liner Liner was installed and held pressure PPM maintained positive pressure all night and next day to allow adhesive proper time to fully cure Re-pressurized and tested pipeline Cut open fish mouth valve position Liner Adhesive filled Drip Starline-1000

28 Pipeline Lining Completed

29 Other Challenges - Flooding

30 Other Challenges Freezing and Blizzard

31 Area Restored Liner Project Complete

32 WG Cast Iron Renewal Technique- Other Liners U-liner Internal sealing technique used in the late 1990 s U shaper liner that expands in pipe Useful on straight pipe with no service connections Remediated about 1000 of main

33 WG Cast Iron Renewal Techniques Internal Joint Sealant I t l j i t l t Internal joint sealants Only plausible on 16 diameter and up More cost effective than external joint sealant because don t have to excavate every joint Projected savings of up to 60% over conventional repair methods Example project Embassy Row internal sealing rehab Remediated about 3,300 of 20 cast iron main

34 WG Cast Iron Renewal Techniques Embassy Row Internal Sealing Rehab History of bell and spigot joint leakage Main in good condition Pipe wall thickness =.71 thickness Less expensive than direct bury 11 customer included Embassy residences Textile museum Large homes

35 WG Cast Iron Renewal Techniques Embassy Row Internal Sealing Rehab Sequence of Work Temporarily transfer services to low pressure main Install new 2 main - transfer services Excavations Gas stop-offs Disconnects Internal sealing Air test main Reconnect pipe segments Stop-off to reconnect last segments Service transfers Additional work

36 WG Cast Iron Renewal Techniques Embassy Row Internal Sealing Rehab Mass Ave 24 th St 23 rd St X Phelps Pl X X X X X X X X S ST Fla Ave X Stop-off (7 x 8 ) X - Disconnect (7 x 20 ) X Entry/Exit (7 x 10 )

37 WG Cast Iron Renewal Techniques Georgetown Internal Sealing Rehab Internal Sealing Seals Nitrile rubber Steel retaining bands Process Internal inspection/count Clean/grout joints Put seals and bands in place Expand steel bands Air test each seal Crews worked inside 20 main for 7 days

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41 Construction

42 WG Cast Iron Renewal Techniques Embassy Row Internal Sealing Rehab Return To Service Air test at 25 psig for 1 hour Return to pressure at 5-psig increments Leak survey between increments

43 WG Cast Iron Renewal Techniques External Joint Sealant E t l j i t l t External joint sealants Same concept as encapsulation kit Considered a repair, not a renewal Not used for mass replacement, but more for big diameter joint repairs Not as cost effective as internal joint sealants

44 WG Cast Iron Renewal Techniques Plastic Insertion Plastic Insertion Used mostly for small, 8 and below diameter Have done some 16 diameter Convert LP to MP after insertion Practice is to purge before insertion, so not done on live gas Complete about 5 miles of replacement annually using the insertion method

45 Questions?