Exploring the Direct Relationship Between Transients and Wire Breaks

February 9 2pm EST

Poll Question

Do you have PCCP lines?

Poll Question

Do you have a budget to repair or replace or do condition assessment of your transmission line (in the next 2 years)?

Reduction of Failure Risk of Prestressed Concrete Cylinder Pipe (PCCP) by

Reduction in Maximum Pressure

Rasko OjdrovicSimpson Gumpertz & Heger

Webinar

Direct Relationship Between Transients and Wire Breaks

9 February 2017

www.sgh.com

Simpson Gumpertz & Heger PCCP Pipeline Experience More than 25 years of research, analysis, design, condition

assessment, failure investigation and repair of all kinds of pipelines

Developed AWWA C304 standard for design of PCCP Developed AWWA C305 standard for CFRP repair design of

PCCP Developed thrust restraint design procedure in AWWA M9

Manual Developed procedure for risk assessment of PCCP with

broken wires Developed Best Practices Manual for WRF Developed concrete pipeline risk ranking for EPRI 100s of projects for pipe investigation, condition assessment,

failure risk analysis, repair prioritization and repair

Embedded Cylinder Pipe (ECP) andLined Cylinder Pipe (LCP)

Prestressed Concrete Cylinder Pipe (PCCP)

PCCP Failure Risk Reduction

This presentation will discuss failure risk reduction of PCCP lines by reduction of maximum transient pressures.

Background on PCCP Structural Analysis of PCCP Failure risk analysis (fitness-for-service) Repair prioritization and repair options

Value

PCCP lines can last a design life with high reliability if properly designed for loads and environment, manufactured, installed and operated

One prevented pipe failure saves $$$$$$$ Rupture repair cost Business interruption Loss of production and revenue Collateral damages Environmental pollution Litigation

Proactive preventive maintenance of pipelines extends the life of these major assets

Risk of Pipe Failure

Likelihood of pipe failure depends on:

Design adequacy (hoop and longitudainal effects) Manufactured quality of pipe and constitutive materials (Class IV wire, mortar

coating, concrete core, etc.) Transportation and handling (damage) Installation (damage, poor bedding, etc.) Corrosivity of environment (Chlorides, pH, etc.) Third party damage Operation loads higher than design loads (soil cover height, live load, transient

pressures)

Higher than design pressures may cause cracking of mortar coating and other damage that may affect pipe durability, need for repair, and failure.

Solution Perform Failure Risk Analysis to determine benefits of pressure

reduction Reduce maximum transient pressure

Strength with contribution of soil

Strength without contribution of soil

Serviceability

Damage

RP1

RP2

RP3

RP4

+

Length of Distress

PCCP Distress Signs Coating cracks and delaminations Corrosion of prestressing wires Broken prestressing wires Longitudinal cracks in inner core Hollow sounding inner core Corrosion of steel cylinder Leak (through joints or steel cylinder)

Mortar Coating

Petrographic analysis of polished and thin sections, SEM Chloride ion concentration in the coating Unit weight, absorption and porosity Cracking significantly reduces protection provided by mortar coating

Prestressing Wire Breakage

Corrosion Embrittlement

Corrosive Environment

Chlorides Sulfates Acids Carbonation Stray currents Coating cracking exposes wires

to corrosive environment

Installation and Damage

AWWA C304 Standard Limit state design procedure Validation testing of PCCP State of stress of PCCP accounting for

creep, shrinkage and wire relaxation UDP program used for analysis and

design of PCCP since 1992

Structural Analysis of PCCP

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

60000

0 25 50 75 100 125 150 175 200 225

Earth

Loa

d (lb

/ft)

Pressure (psi)

Limit State Curves for Class 100 psi PipeCoreMicrocracking

CoatingMicrocracking

Cylinder Yield

Wire fsg

Wire yield

0.75 f 'c

Envelope

Core Cracking

Coating Cracking

We

Pw Pw + Pt

Structural Analysis of PCCP Combined Loads

PR50P

6826 122.15156.5 153.46 165.93 205.03 410890.69Cylinder Yield (G)Wire fsg (H)Wire yield (I)0.75 f'c (J)Core Cracking (L)Coating Cracking (M)Pressures

PressureCore MicrocrackingCoating MicrocrackingCore CrackingCoating CrackingCylinder YieldWire fsgWire yield0.75 f'cEnvelopeCore CrackingCoating Crackingxx+1xx+1xx+1xx+1xx+1xx+1xx+1

1014447.8620730.3418059.8333668.6530319.6335413.9839350.2934609.4218059.8330319.6330319.6300000000000-174600166157

23.4114447.8620247.6718059.8333668.6530319.6335025.6538874.5234410.9818059.8330319.6330319.63000-811000000-1746136800157148

36.8314447.8619745.3518059.8333668.6530319.6334607.738375.4434203.7918059.8330319.6330319.6300-8116984000-60900136843780-1237148140

410.2414447.8619242.2918059.8333668.6530319.6334187.8537874.5733987.4518059.8330319.6330319.630069841434500-60954901224143787284-12372461140131

513.6514447.8618738.4618059.8333668.6530319.6333766.0637371.8833762.0618059.8330319.6330319.630014345174830-11205492367122411339572841008924615724131122

617.0614447.8618233.7918059.833322230319.6333342.2836867.3333473.8118059.8330319.6330319.63001748320551-11202012236756441339514468100891280457248746122113

720.4814432.9117728.2318059.8332504.3930319.6332916.2336360.8833169.6918059.8330319.6330319.63002055123144201249655644911914468161851280415365874611543113104

823.8914045.5817221.7318059.8331776.1230319.6332485.9235852.532850.3518059.8330319.6330319.630023144255014965876591191349516185179731536517393115431416710496

927.313659.8316714.2318059.8331040.430319.6332058.6935342.1432515.0818059.8330319.6330319.630025501255018765876513495134951797317973173931739314167141679696

1030.7113263.9216205.6418059.8330296.9830319.6331626.3234829.7732163.0618059.8330319.6330296.8100255012640987651025213495151631797318674173931813814167151459692

1134.1312892.3515695.8918059.8329545.5630319.6331190.2834315.3431793.3318059.8330319.6329545.56002640927312102521171315163168161867419389181381893115145161059289

1237.5412503.2415184.9118059.8328785.8630319.6330753.5933798.8231404.6818059.8329739.6228785.86002731228210117131314916816184531938920121189311969216105170468985

1340.9512112.514672.5818059.8328017.5330319.6329892.8633279.6330996.218059.8329083.5628017.53002821029102131491456218453200752012120872196922044717046179708582

1444.3711721.2114155.9518059.8327240.2430319.6328707.9132756.1530585.0918059.8328380.9727240.24002910229989145621595420075216832087221643204472119717970188788278

1547.7811331.4513643.4518059.8326453.6230319.6327568.9932236.4829620.7918059.8327691.8226453.62002998930320159541732621683232812164322447211972194018878197677875

1651.1910940.0913126.318059.8325657.2730319.6326463.2731711.0828691.9418059.8326988.525657.27003032030320173261867923281248752244723251219402267519767206497572

1754.610548.7712607.318059.8324850.7830319.6325206.2831180.4327714.1518059.8326280.3424850.78003032030320186792001524875264242325124092226752338320649215147268

1858.0210153.3512086.2918059.8324033.6730319.6323929.9430340.0126801.918059.8325567.5124033.67003032030320200152001526424264242409224092233832338321514215146868

1961.439757.4711563.118059.8323205.4730319.6322639.8729156.2925870.2118059.8324850.3923205.47003032030320200152133526424277232409224965233832407621514223666865

2064.849362.711037.5318059.8322365.6330319.6321335.2927723.0824965.2418059.8324075.9322365.63003032030320213352264027723291562496525870240762485022366232056561

2168.268964.4910509.3418059.8321513.5930319.6320015.3426424.3524091.9718059.8323383.321513.59003032030320226402393029156303402587026802248502556823205240346158

2268.260018059.8321513.5930319.6320015.3426424.3524091.9718059.8323383.321513.59003032030320239302520630340311802680227714255682628024034248515855

2271.6718059.8320648.730319.6318679.1124875.1223250.6818059.8322674.9520648.7003032030320252062646331180317112771428692262802698924851256575551

2375.0818059.8319767.4830319.6317325.5623280.7922446.6317325.5621939.7819767.48003032030320264632756931711322362869229621269892769225657264545148

2478.4918059.8318877.5829989.1715953.5321682.5621642.8415953.5321196.5618877.58003032030320275692870832236327562962130585276922838126454272404844

2581.9118059.8317969.6829102.0114561.7420074.6520871.6714561.7420447.0817969.68003032030320287082989332756332803058530996283812908427240280184441

2685.3218059.8317045.7328209.8113148.7318452.5320121.3213148.7319691.5817045.73003032030320298933075433280337993099631405290842974028018287864138

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2995.5617393.2914166.6325500.918764.621349517973.188764.6217393.2914166.63003032030320316263205934830353423216332515303203032030297303203127

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