Echologics - Drinking Water Management Resources for ...

EchologicsPipeline Condition Assessment Using External Acoustic Technology

PNWS AWWA Conference, Eugene, May 7, 2014

Presented by Carl Sharkey, Regional Mgr.

Meet Echologics

• Provider of specialized services for water loss management, large main leak detection and pipe condition assessment▸ Isolates leaks and determines remaining service life

• History of the company▸ 2003: Echologics founded as joint venture

• Federal research institute• Acoustic engineering firm

▸ 2004: Leak detection equipment for non‐metallic pipes▸ 2005: Transmission main leak detection services▸ 2006: Pipeline condition assessment technique pioneered.▸ 2008: Pipeline condition assessment technique commercialized▸ 2011: Echologics acquired by Mueller Water Products, Inc.

The Basic Question

Pipeline 1 Pipeline 2Installed 1860 Installed 1860Brown clay soil Brown sandy soilModerate soil corrosivity Moderate soil corrosivity

Exhumed & sand blasted: Exhumed & sand blasted:

Presentation Outline

• Basics of pipeline degradation• Principles of acoustic pipeline assessment• Equipment used & inspection methods• How the inspection results are used and the benefits• Case Studies

Why do Pipes Fail?

• Joint problems• Ground shifts• Temperature cycles• Corrosion• Calcium leaching out of asbestos cement• Third party damage• Unplanned traffic loads• Pressure surges

Why do Pipes Fail?

• Due to Loss of Strength or unplanned Stress, the pipe is no longer strong enough to with stand the Stress placed on it

A pipe’s lifetime

Age

Bursts per mile per yr

Installed defect failure period Random failure period

Degradation related failure period

Maximum economical failure rate

Methods of pipe assessment

• Direct▸ Visible internal conditions▸ Presence of non‐surfacing leaks▸ Material analysis of pipe samples▸ Remaining pipe wall thickness

• Indirect▸ Failure history▸ Water loss rate▸ Flow testing▸ Soil testing

Ways of Measuring Wall Thickness

Detection of individual defects

Inspect Entire Pipeline

Desktop studies

Average wall thickness assessment

Spot checks with statistical extrapolation

Full length inline testing

Assess general pipeline condition

Inspect Part of Pipeline, Predict the Rest

More detailed inspection

More complete pipe wall coverage

Acoustic Wall Thickness Assessment

Pipe Wall Thickness

• Direct indicator of structural condition.

• Indicator of level of degradation of the asset.• Metallic pipes lose thickness due to corrosion.

• Asbestos cement pipes lose effective thickness by the weakening of the wall as calcium leaches out of the cement due to aggressive waters.

• Reinforced concrete pipes lose stiffness as a result of the weakening of the concrete or corrosion‐failure of pre‐tensioning steel.

Established Methods to Measure Remaining Wall Thickness Pipe sampling programs

• A sample or coupon is taken every 1 mile of pipe• Intrusive and disruptive

• Sample is sand‐blasted and measured, and remaining life of entire pipeline extrapolated from sample

• Exhumed samples may not be representative• Difficult to account for local environmental variations

Inline electromagnetic methods• Required instrumentation is sent inside pipes using smart pigs

• Often requires shutdown of the line, installation of launch & retrieval sites, and cleaning of pipes to remove tubercles and debris

• Provides a continuous profile of pipe‐wall thickness.• Data acquisition and analysis are labor and cost intensive• Cost and level of disruption are too high to be justified for most pipes

Acoustic Wall Thickness Testing• Determines the average remaining wall thickness between

two points of the pipeline• Typically about 300‐500 LF of pipe

• Works on any diameter, any material

• Completely non‐destructive, non‐invasive technique

• Direct indication of• The current structural strength of the pipe

• The state of degradation of the pipe

• Can be used to evaluable• The fitness for service of the line

• The remaining useful life

Acoustic Pipeline Assessment

• A low frequency acoustic pressure wave is induced in the pipe▸ Dominated by a non‐dispersive axi‐symmetric mode (S1,n=0)

• This pressure wave causes pipe wall to “flex” on a microscopic level

• Thicker (and therefore stiffer) pipe walls are more resistant to this “breathing,” causing the wave to travel faster

• Measuring this phenomenon allows calculation of remaining wall thickness

Structural Wall Thickness: A Direct Measurement of Structural Strength

• Average structural wall thickness▸ Band of continuous material

Tuberculation: Not structural, not measured

Structural Wall Thickness: Maximum continuous band of metal

Graphitized material: Not structural, not measured

Longitudinal Crack: Reduces structural thickness over its full length

Tuberculation and graphitic material cannot bear load

Remaining structural thickness

Structural Thickness in Cast Iron

Structural Thickness in Asbestos Cement

• Calcium leaches out of cement in reaction to aggressive waters• Remaining material cannot bear structural load• Phenolphthalein dye reveals remaining thickness from samples

Remaining structural thickness

Equipment Used

Echologics LeakFinderRT:PC‐based leak noise correlator

Acoustic Condition Assessment: Field Testing

Noise Source

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• Pressure >= 15 psi• No air in pipe• Accurate pipe information

(maps, as‐built, specs)• Access points, ideally every

300‐500 ft

Method Requirements

Sensor Attachment Options

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Why LeakFinderRT?

• Advanced custom‐engineered sensors• Proprietary signal processing software• Most effective correlator on non‐metallic pipes• With special training and equipment, effective even on large diameter pipelines.

• Extremely easy to use• Number one in accuracy

Condition Assessment Results

• Presence and location of any leaks• For each assessment interval:

▸ Remaining structural thickness▸ Percent loss from original thickness▸ Qualitative assessment of condition

• Based on pipes tested & exhumed for validation

What it tells you

Pipeline 1 Pipeline 2

Installed 1860 Installed 1860

Brown sandy soil Brown clay soil

Moderate soil corrosivity Moderate soil corrosivity

Echologics Results: 31% thickness loss Echologics Results: 1% thickness loss

Condition Prediction: Poor Condition Prediction: Good

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Serviceable Lifetime Prediction: What is it?• Models developed to predict remaining serviceable life

based on condition assessment measurements.• Based on the measurement results and current loading

conditions of the pipe (pressure and depth), an estimate will be provided on how many more years the pipe can be used

• Provides an accurate idea of when in the future the pipe will need to be rehabilitated or replaced

Serviceable Lifetime Prediction:How is it calculated?Remaining Lifetime Prediction• The degradation rate (t*) of the mains can be calculated

knowing the installation date, nominal thickness and current thickness.

• The Schlick Failure Criterion can be used to predict the minimum required thickness to sustain the combined internal and external loading on the main.

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Serviceable Lifetime Prediction:How does it work?

• The current thickness of the pipe is measured using Echologics method

• A linear extrapolation is performed by using the measured thickness, the nominal thickness and the installation date

Installation Date

Measurement Date

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Serviceable Lifetime Prediction:How does it work?

• The Failure thickness is predicted by calculating the minimum required thickness to carry the given loads

• The loads include: internal pressure from the water column and external pressure from the soil and traffic loads

Failure Thickness

Added Benefit: Detect Leaks!

• While doing acoustic condition assessment, Echologics will detect leaks on the pipeline.

• Effective on any material• Effective on any diameter

▸ Even large diameter trunk mains!▸ Echologics is the first company to solve the challenges of external leak

detection on trunk mains:• Low frequency of leak sounds• Large amounts of competing noise sources• Long spacing between sensor access points

• Note: Trunk main leak detection is also available as a stand‐alone service, but is automatically provided with condition assessment.

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Benefits of Acoustic Condition Assessment• Scalability

▸ Cover larger areas with one crew (~.66 mile/day)

• Ease of use▸ No need for specialized

access, road repairs or service disruptions

• Reduction of NRW▸ Leak detection is part of the

service▸ On average, find 1 leak per

mile of pipe surveyed

• Top‐down approach▸ Large areas covered for lower costs than intrusive in‐pipe technologies

▸ Screening performed on large areas to identify problems and avoid rehabbing or replacing pipes in good condition

Make use of results

• Acoustic wall thickness measurements agree with destructive physical tests

• This data can be extremely valuable• Example: Las Vegas pilot included 10 miles of pipe budgeted

for removal▸ Found 2.5 miles of this pipe to be in excellent condition▸ Savings to utility of over $2M

Systematic Program

• Include wall thickness in replacement prioritization model• Network‐wide assessment of pipe wall thickness and leakage• Depending on size of network, and available funds, surveys

may be spread over several years

Benefits of Acoustic Method

Non‐intrusive, non‐disruptive

Works on all types of pipes

Survey level technology works with all other detailed survey technologies

Leak detection automatically performed at same time

Summary: External Acoustic Condition Assessment

• Average wall thickness over ~300‐500 ft intervals

• Reflects structural strength of pipe

• Non‐destructive, non‐intrusive method

• Survey‐level technology, for network‐wide application

• Leak detection performed concurrently

• Can be used to calculate remaining useful life

Applications To Asbestos Cement Piping

• Many European utilities faced with significant amounts of AC pipe nearing design life

• Cost of replacement is inflated by need to follow asbestos handling regulations

• Preferable to leave in service so long as it remains in good condition

ACP Results

Line 1 Line 2Echologics assessment: < 5% thickness loss

Echologics assessment:38% thickness loss

Actual conditions: Actual conditions:


• Basics of pipeline degradation• Principles of acoustic pipeline assessment• Equipment used & inspection methods• How the inspection results are used and the benefits• Applications to Asbestos Cement piping• Case Studies

Case Study: Newark Department of Water & Sewer UtilitiesProblem:• City relining water pipe below high traffic

road• Project carried estimated cost of more than

$60,000 Results/Remediation:• ¼” service leak immediately located (annual

marginal cost of water lost > $20,000) • Identified section of pipe that lost 64% of

structural integrity• Leak repaired• Identified section of pipe that required

replacement• Insufficient structural strength for relining

• City revisiting plans for annual distribution main rehabilitation program

Case Study: Bristol, UK• Condition assessment study of AC and cast iron mains• Leak detected on 30” cast iron main

Hamilton, Ontario

• Tests performed in city water distribution system

• 10 test sites with large and small diameter cast iron pipes at different expected levels of deterioration

• Selected pipes installed between 1860 and 1960

• Remaining thickness predicted by new method

• Samples exhumed to verify Echologics method, based on visual appearance and average wall thickness

Hamilton, Ontario

Site 3 Site 7

Installed 1860 Installed 1860

Brown sandy soil Brown clay soil

Moderate soil corrosivity Moderate soil corrosivity

Echologics Results: 31% thickness loss Echologics Results: 1% thickness loss

Condition Prediction: Poor Condition Prediction: Good

Maple Ridge, British Columbia (BC)

• City needed method to determine which pipes to prioritize for replacement

• Knew where some pipes were degraded and wanted to accurately identify them

• Wall thickness: 0.3 inches or ‐54.2%• Maple Ridge excavated this pipe and it looked like porridge

Case Study: Las Vegas Valley Water Department• Identified mains that did NOT need rehab or replacement• Saved 2.5 miles of 16” to 36” bar‐wrapped steel cylinder

transmission main for 10 miles surveyed• Reduced budget by $2,000,000

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Case Study for Asbestos Cement (AC) for Las Vegas, NV• Asbestos cement pipes lose “effective thickness” by the

weakening of the wall due to the leaching out of cement by aggressive waters

Las Vegas, NV

Las Vegas, NV: Results

• 5 year renewable contract to assess AC and critical transmission mains

• Assessed all AC in Las Vegas, NV• Most AC in excellent condition• Several areas of degraded AC pipe found• 24” pipe assessed to be 38% degraded

Las Vegas, NV

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