Practical Solutions to External Corrosion Problems …...Jeff Schramuk NACE CP Specialist #7695 4/24/2015 1 1 Practical Solutions to External Corrosion Problems on Buried Water Mains

Jeff Schramuk NACE CP Specialist #7695

4/24/2015

www.cpsolutionsinc.net 1

1

Practical Solutions to External Corrosion Problems

on Buried Water Mains

Jeff SchramukNACE CP Specialist #7695

630-235-1559www.cpsolutionsinc.net

Illinois Section AWWA Annual WDC: 4/28/2015

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1. Corrosion Problems Facing Water Utilities

2. Asset Management

3. Understanding Corrosion Terminology

4. Pipe Materials and Coatings

5. Basic Cathodic Protection

6. CP for Existing WMs using an Anode Retrofit Program

7. Solving Corrosion Problems at WM Breaks

8. Cathodic Protection Performance Verification

Topics to be Covered


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Module 1 Corrosion Problems

Facing Water Utilities

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What’s the Rest of the (Unexcavated) Pipe Look Like?


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What Are the Consequences of Pipeline Failures?

Water Main BreaksEnergy Pipeline “Incidents”

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Module 2 Asset Management


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“A water utility’s asset management plan is an optimization process that

attempts to meet the competing objectives of cost minimization and

reliability maximization.”

Source: Rubin, S.J., A Call for Reliability Standards, Journal AWWA, (Jan-2011)

Asset Management: A Real-World Definition

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Risk = (Likelihood of Failure) x (Consequence of Failure)

Evaluating Failure Risk: Probability vs. Consequences


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Module 3 Understanding

Corrosion Terminology

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Anode – A metal electrode in contact with the electrolyte which corrodes.

Cathode - A metal electrode in contact with the electrolyte which is protected against corrosion.

Electrolyte – A solution or conducting medium such as soil, water or concrete which contains oxygen and dissolved chemicals.

Metal Path – An external circuit that connects the anode and the cathode.

Four Components of a Basic Corrosion Cell


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Anodic Area

(Metal Loss)

DC Current

Cathodic

Area

(Protected)

Anodes & Cathodes on a Buried Metallic Pipe

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Module 4 Pipe Materials and Coatings


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Eliminating the Corrosion Cell

Ste

el a

t -6

00

mV

Cop

pe

r a

t -2

00

mV

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Mortar Integrity on Reinforced Concrete Pipe

Photo courtesy of CP Solutions, Inc. – Bartlett, IL …but is there latent damage?

New installation looks good…


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Prestressed Concrete Cylinder Pipe – Corrosion Failures

Photo Credits: CP Solutions, Inc.

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Large Diameter Coated Steel Pipe – Installation Photos



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Coating Integrity on Coated Steel Pipe

Photo courtesy of CP Solutions, Inc. – Bartlett, IL

…but is there latent damage?New installation looks good…

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Poly-Wrap Integrity on Ductile Iron Pipe

Photo courtesy of CP Solutions, Inc. – Bartlett, IL…but is there latent damage?

New installation looks good…


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Rip and tears in the poly wrapping

leave the pipe exposed

Oxygen and water can travel

beneath the poly wrapping

Loose Polyethylene

Wrapping

Ductile Iron Pipe

Soil Contaminants

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Have you ever tried to track down a joint leak within a poly-wrapped water line?

Loose Poly Wrapping – An Effective Corrosion Barrier?

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Epoxy Coated Valves & Fittings – Before Burial



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Epoxy Coated Valve – After Burial

Photo Credit: CP Solutions, Inc.

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Module 5 Basic Cathodic Protection


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Basic Corrosion: Corrosion occurs where DC current

discharges from the metal to the electrolyte.

CP Objective: To allow your structure to receive DC current

(be cathodic) from an expendable anode placed in the soil.

How Cathodic Protection Works

Material Potential*Pure Magnesium -1.75

Magnesium Alloy -1.60

Zinc -1.10

Aluminum Alloy -1.00

Mild Steel (New) -0.70

Mild Steel (Old) -0.50

Cast / Ductile Iron -0.50

Stainless Steel -0.50 to + 0.10

Copper, Brass, Bronze -0.20

Gold 0.20

Carbon, Graphite, Coke 0.40*Measured in Volts versus a Cu-CuSO4 Reference Electrode

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Le

ss

Active

M

ore

Practical Galvanic Series


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Ca

tho

de

Ca

tho

de

An

od

e

1. Anode

2. Cathode

3. Electrolyte

4. Metal Path

Galvanic Corrosion Mitigated w/Cathodic Protection

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Typical Horizontal Sacrificial Anode Installation

Sacrificial Anode

Coating Defect

Connection to Pipe

Grade


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Module 6 Cathodic Protection

for Existing Water Mains

using an

Anode Retrofit Program

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Anode Retrofit Program (ARP) - A method to

install sacrificial anodes to buried water mains.

Since 2003 – Louisville (KY) Water Company

Since 2004 – Des Moines (IA) Water Works

Since 1980’s – Many Ontario (Canada) Water Utilities

More Recently – Several California Water Utilities

Anode Retrofit Programs – An Overview


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Anode Retrofit Program - Purpose

Reduce the Number of Broken Water Mains

Extend Service Life of Water Mains

Reduce Operating Costs of Water Mains

Photos courtesy of CP Solutions, Inc. – Bartlett, IL

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DMWW’s Long-Term Main Break Data (1994-2011)

After 2007 there are approx. 30 annual breaks per 100 miles pipe (excluding rural water system)

0

50

100

150

200

250

300

350

400

Nu

mb

er

of

Bre

aks

Year

Total Main Breaks - Trends


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$2,500

$3,500

$4,500

$5,500

$6,500

$7,500

2000 2002 2004 2006 2008 2010 2012 2014 2016

Rep

air

Co

st/

Ma

in B

rea

k

Year

Repair costs have doubled since

2000

DMWW’s Main Break Repair Costs (2000-2013…)

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Typical Anode Retrofit Installation Method


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Keyhole to Pipe & Wire Connection

Exothermic Welding Tool Down the Hole

Testing the Wire Connection

Photos courtesy of CP Solutions, Inc. – Bartlett, IL

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Alternative (Non-Keyhole) Installation Methods


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Does the data show that retrofitting CP

anodes on water mains actually

reduces the main break rates?

Main Break Reduction Evaluation of the DMMW’s ARP

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DMWW Main Break Comparison – ARP vs. No-ARP

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

Cu

mu

lati

ve S

um

Mai

n B

reak

s

Year

No-ARP(1985-ARPYear)

With ARP(ARP Year-2012)

*Source: “Implementing and Managing a Large Water Utility’s Underground Corrosion Program,” Journal AWWA, Vol. 104, No. 7, July 2012

Break reduction

after ARP

Extrapolated prior

break data w/o ARP


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Economic Evaluation of the DMMW’s ARP

But does the economic data show that retrofitting CP

anodes on water mains is actually

cost-effective?

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DMWW Anode Retrofit Program: 2004-2011 Summary

ARP installed on ~82,000 feet of 6” - 16” cast iron mains

ARP costs are $9 to $15/ft. pipe

ARP cost ~10-15% of break repairs/pipe replacement

ARP resulted in average reduction of 85% in main breaks

ARP adds a ~25-year service life extension to water mains


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Module 7 Solving Corrosion Problems

at Water Main Breaks

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What’s Your Biggest Cost to Repair a Main Break?


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Do I really want to re-excavate this hole for

another water main break?

“Hot-Spotting”: CP Anodes at Water Main Breaks

Install a sacrificial CP anode while the water main repair excavation is already open!

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Document all leak and main break repairs as

recommended by AwwaRF

Install a sacrificial anode every time the main is

exposed for repairs or tapping.

Install the anodes where earlier leak problems

have occurred

Source: Research Applications, Proven Utility Benefits, Paper #8, AwwaRF, August 1995.

AWWARF Shows that CP Reduces Main Breaks


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Cost of repairing a water main break

versus

installing a sacrificial anode during a pipe repair...

Average Cost of a Main Break

$3,500 to $5,000

Cost of a CP Anode and a Connection Device

Less than $150!

Cathodic Protection Is Proactively Inexpensive

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Use a Secure Connection to Attach Sacrificial Anodes

sacrificial

anode

Connection

device


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Safe Work Practice in Wet Trench Conditions

Safe to install in standing water

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Module 8 Cathodic Protection

Performance Verification


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.900 V

+

Reference Electrode Placed into Soil

Directly Above Pipe -

Electrical Contact to

Pipe

Area of Pipe “Measured”

Structure-to-Soil Potential w/Portable Reference Electrode

VM (-) connected to second pipe

test wire

VM (+) connected toPortable Reference Electrode

Voltmeter set on DC VoltsBlue = Pipe Wire (1 of 2)

Red = Anode Wire

CP Performance Validation – S/S Potential Data


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Increased water main service life

Increased level of reliable water service to customers

Increased health and security of the municipal water supply

Summary: The Real Benefits of Corrosion Mitigation

Cathodic protection saves $5 to $10 for every $1

spent resulting in…

Water Main Life Extension of least 25 years at acost that is much less than…

Direct costs of pipe repairs and/or water main replacement.

Indirect costs resulting from water loss/service disruptions.

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Jeff SchramukNACE CP Specialist #7695

630-235-1559www.cpsolutionsinc.net

Do You Have Any Questions?

All material in this presentation is, unless otherwise stated, the property of CP Solutions, Inc (CPSI). Copyright and other intellectual property laws protect these

materials. Reproduction or retransmission of the materials, in whole or in part, in any manner, without the prior written consent of CPSI, is a violation of copyright law.

Illinois Section AWWA Annual WDC: 4/28/2015

Documents

Practical Solutions to External Corrosion Problems …...Jeff Schramuk NACE CP Specialist #7695 4/24/2015 1 1 Practical Solutions to External Corrosion Problems on Buried Water Mains