Cast Iron Rene al Techniq esCast Iron Renewal Techniques...ti itwin main • The pipeline after depressurizing was almost completely dry with ... Cured-in-place Lining Technology.

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


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


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


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?

Cast Iron Rene al Techniq esCast Iron Renewal Techniques...ti itwin main • The pipeline after depressurizing was almost completely dry with ... Cured-in-place Lining Technology.

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