Cast Iron Rene al Techniq esCast Iron Renewal Techniques
Katie Harkless
Project Manager-Replacement
Washington Gas
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 fieldand 1 storage field
2
WG Cast Iron Piping
DC 428 il• DC – 428 miles• MD- 75 miles• VA – 17 MilesVA 17 Miles• Total cast iron = 520 miles• Replace 5-6 miles annually
WG Cast Iron Renewal Techniques
Li• Liners– Cured-in-place liner– U-liner
• Joint sealants– Internal joint sealants
External joint sealants– External joint sealants• Insertion
– Plastic insertion
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)
Cured-In-Place Anacostia River Rehab Project
C d i l• Cured-in-place process– Disconnect pipe– Clean pipe– Pre-lining inspection (CCTV)– Lining process– Post-lining inspection– Post-lining inspection– Pressure test– Activate the line
Anacostia River Rehab Project
B k d f th P j t• Background of the Project– 16-inch cast iron pipes leaking under river Winter 2009
• Replace Option p p– Drill new lines– Install new lines through Anacostia Park
Complete line replacement– Complete line replacement • Rehabilitation Options
– Insertion– Lining – selected as best option
River Crossing Location
Project Design Concerns
C l t d t d i i f th i d ibl t• Concerns related to depressurizing of the main and possible water infiltration
• Double lining considered, first lining to stop water infiltration & d f isecond for gas carrier
• Obtaining Permits from Parks Dept• Working from Vault Side without dismantling the vault• Environmental issues related to dewatering of park side pit
Pipeline Inspection
D i i f th Fi t L f T i 16 I h iDepressurizing of the First Leg of Twin 16-Inch main –Phase I
• Consideration was given to live camera inspect while simultaneously l i th t it t i filt tilowering the gas pressure to witness any water infiltration
• WGL opted not to live camera inspect and depressurized first leg of t i itwin main
• The pipeline after depressurizing was almost completely dry with l th fi t t t i j i t i littl tonly the first two cast iron joints weeping a little water
Cured-in-place Lining Technology
Pipeline Before Cleaning to Final Product
Camera Inspection
W ki f th k id f th j t th fi t i ti f th• 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 p
valve
Debris
Drip
Blast Hose from Vault Side
Pipeline Cleaning
Cleaning Process
Filling the Drip
Valve
Drip filling Methodology
• Inserted 2-14-Inch pigs into the bottom of the drip Camera
• Inserted 90ft of 2-Inch PVC pipe
• Mixed and poured adhesive into 2-Inch pipe and fill drip (27 Cans used)
2-14” Pigs
• Observed process through camera
Lining Process
Lining Process
PressureDrum
Concrete Vault Sub Station Side
Drum
P k Sid With St l
Direction of Lining
Drip filled with2-Pigs & Adhesive
Park Side With SteelSheeting Box
Lining Process
Clearance Concerns
Important: For every two feet (2ft) of additional cover, top of main,The cut-out section of space between the mains MUST increaseBy one additional foot (1ft) for example, a pipe with 6 feet (6ft) of
Cover requires a 7 foot (7ft) cut-out
6ft SectionRemoved
2-Foot
Section to be Lined
Utility Requirement
Removed@ 4FT cover
1-Foot
be Lined
Clearance Requirements
Side View
PressureDrum
Approx 40ft LongIncluding Trucks4ft
DirectionOf Lining
Approx 10-12ft Long
Including Trucks
1ft
Approx 10 12ft Long
Consequences of Misalignment
• Misalignment at the inversion point creates unsupportedliner within the rehabilitated pipeline and a
“Spot Repair” is required after curing
Unsupported liner
liner
Not enoughSpace to properlyAlign hose fittingAlign hose fitting
Unsupported liner
Loading the Lining
Inversion Cone Being Connected to Liner
Lining
Line Complete
Valve
Half/Pig to support Liner
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
Lineradhesive proper time to fully cure• Re-pressurized and tested pipeline• Cut open fish mouth valve position
Adhesive filled DripStarline-1000
Pipeline Lining Completed
Other Challenges - Flooding
Other Challenges – Freezing and Blizzard
Area Restored – Liner Project Complete
WG Cast Iron Renewal Technique- Other Liners
U li• U-liner– Internal sealing
technique used in the l t 1990’late 1990’s
– U shaper liner that expands in pipe
– Useful on straight pipe with no service connections
– Remediated about 1000’ of main
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
WG Cast Iron Renewal Techniques –Embassy Row Internal Sealing Rehab
Hi t f b ll d i t j i t l k• History of bell and spigot joint leakage• Main in good condition
– Pipe wall thickness = .71” thicknessp• Less expensive than direct bury• 11 customer included
E b id– Embassy residences– Textile museum– Large homes
WG Cast Iron Renewal Techniques –Embassy Row Internal Sealing Rehab
Sequence of WorkSequence of Work
• Temporarily transfer services to low pressure main
• Install new 2” main - transfer services• Excavations• Gas stop-offs• Disconnects• Disconnects• Internal sealing• Air test main • Reconnect pipe segments• Stop-off to reconnect last segments• Service transfers• Additional work
WG Cast Iron Renewal Techniques –Embassy Row Internal Sealing Rehab
Pl
Ave
e24th
St
23rd
St
Phe
lps
P
X
Mas
s A
Fla
Ave2 2 P
S STX X X X X X X X
X – Stop-off – (7’ x 8’)
X - Disconnect – (7’ x 20’)
X – Entry/Exit – (7’x 10’)
WG Cast Iron Renewal Techniques –Georgetown Internal Sealing Rehab
I t l S liInternal Sealing– Seals
Nitrile rubber• 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– Crews worked inside 20 main for 7 days
Construction
WG Cast Iron Renewal Techniques –Embassy Row Internal Sealing Rehab
Return To ServiceReturn To Service
• Air test at 25 psig for 1 hour
• Return to pressure at 5-psig increments
• Leak survey between increments
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
WG Cast Iron Renewal Techniques –Plastic Insertion
Pl ti I ti• Plastic Insertion– Used mostly for small, 8”
and below diameter• Have done some 16”
diameter– Convert LP to MP after
i tiinsertion– Practice is to purge before
insertion, so not done on lilive gas
– Complete about 5 miles of replacement annually using th i ti th dthe insertion method
Questions?