quantitative acoustic emission (qae)

Quantitative Acoustic Emission (QAE)

Tom Watkins, CM

Manager, Client Support

Margan

April 16-17, 2013

Objectives

• Why inspect High Energy Pipe (HEP)?

• What is QAE Technology?

– A Non-Destructive Inspection (NDI) screening & monitoring tool

• How does QAE work?

– The phenomenon of acoustic emission

Objectives

• What is the QAE process?

– Equipment / Installation / Testing / Analysis

• Applicability

– P22 and P91

• Case studies

– Effectiveness, advantages, and cost savings

• Summary

Protect Physical

Assets and Employees

Aging Plants

Operation

P21 / P91

Uncertainty

Reduced Safety Factors

Comprehensive

Inspection

Program

Why Inspect HEP?

What Is QAE

• A passive system

– Converts released flaw development energy into acoustic signature

– Does not induce seismic or sonic energy into the HEP

• On-line system

– Sensing devices are installed while on-line

– Data is collected while on line

What Is QAE

• A Predictive Maintenance (PdM) tool for your Reliability Centered Maintenance (RCM) tool kit

– Flexible coverage • 100% or can be limited to high risk zones

• Can move traditional NDE from time based to conditioned based inspections

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What Is QAE

• A monitoring process

– Continuous real time or period based

– Entails trending data

– Provides early alert to developing issues

What Is QAE

• A strategic – screening tool

– Optimizes knowledge of HEP integrity over time • Provides visual map

– Assists in prioritizing NDE inspection efforts • UT, MT, LPA, replication

– Reduces uncertainty • Provides sense of urgency

– Facilitates outage planning

What Is QAE

• A strategic – screening tool

– Helps improves budget process

– Enables cost reductions

– Helps defer or avoid unnecessary NDE

– Reduces need for • Scaffolding

• Insulation removal

QAE Limitations

• Indication must be active – Emit or resonate when placed under stress

• Does not “precisely” locate indication along linear length – +/- 10% (or approximately 1 foot)

• Does not differentiate between surface and subsurface location

• Does not provide size of indication

QAE Limitations

• Sensitive to background noise fluctuation and magnitude

• Can be overly sensitive – Small but very active indications

• Multiple flaws near same location cannot be differentiated

Tree Falls

Paper Tear

How Does QAE Work?

Fracture or deformation processes in differing materials have different signatures.

Fracture or deformation processes in differing materials have different signatures.

ICE CRACK Glass Ice Crack Break Glass

How Does QAE Work?

QAE System Collects and Converts

Acoustic Emission is a phenomenon of sound and ultrasound wave radiation in materials that undergo deformation and fracture processes.

How Does QAE Work?

Burst AE is a qualitative description of the discrete signal's related to individual emission events occurring within the material Continuous AE is a qualitative description of the sustained signal produced by time-overlapping signals

How Does QAE Work?

J1 Critical

Flaw accumulation and development

•Micro / macro-cracking

•Fracturing and de-bonding of hard inclusions

•Creep development.

Mechanical impacts and friction

•Hanger impacts and knocks

•Friction at side supports

•Dynamic overstressing

•Shock waves due to steam pulsation

Leaks, malfunctioning valves, and steam fluctuations

•Leaks

•Malfunctioning valves

•Steam fluctuations due to control problems

What Can QAE Detect?

Type I – Flaw Suspected activity

Type II – Impact and friction

Examples of AE Sources

Margan confidential and proprietary information

Examples of AE Sources

Valve Leaks Malfunctioning Valves

Leaks

Leak


What Is Margan’s QAE Process?

Equipment System Design & Installation

Data Acquisition

Data Analysis Report


Equipment

• P22 Waveguide

– Provides signal pass & dissipates heat before sensor

– ¼” Stainless steel with an aluminum flux ball

– Ceramic sensor converts pulse to electrical signal

EPRI Margan


Margan

Equipment

• P91 Waveguide

– P91 material welding attachment standards require • Capacitor welding method

– A specific waveguide


Equipment

• Other – Cable – Preamplifier – BNC Cable Connectors – Resonance Sensor – Integrated Pre-amplifier – AE PCI 4 Cards – Software

Cable

Cable Trays

BNC Connector

Sensor +

Preamplifier


Design

• Sensors strategically spaced

– Sensor spacing is function of sensor sensitivity, background noise, piping accessories, attentuation, etc.

• EPRI guidelines – 15 to 18 feet in low background noise

– 10 to 13 feet in high background noise

• Margan procedure – 12 feet maximum

– Increased sensitivity and reliability

– <3 feet from piping accessories

– Wye blocks, attempterators, hangers, etc.

– Install on same circumferential side of pipe


Installation

Minimal Insulation Removal

Terminal Point Welding Waveguide No Scaffolds - Rope Access


Data Acquisition

• Margan uses 3 calibration protocols

1) Sensor response to a preset noise level

2) Acoustic emission energy distribution

3) Sensor attentuation v distance to sensor

• Calibration is critical stage for accuracy


400

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0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000

Background noise energy

Ene

rgy

with

the

nois

e g

ener

ator

5DV1CR13 Vermilion U1 CRH p1-25 March 08 noise Energy

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Point

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age

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gy

Source #P 12

P 18

P 17

P 16

P 15

P 14

P 13P 11

P 10P 9

P 8P 7

P 6

0

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-20 -15 -10 -5 0 5 10 15 20

Position[m]

Ener

gy [a

.u.]

a

b

Data Acquisition


Margan Procedures EPRI Guidelines

Most of the inspection is performed under

stable load conditions of plant operation.

During baseline, it is recommended to perform

low and variable load measurements (see

below)

Stress method should not excessively stress the

piping. Piping should be monitored under

normal stable conditions.

Variable load measurement- the load swings

between 90% to 100% of full load back and

forth. This is done to monitor dormant flaws,

which emit under changes in stress.

The load swing should include a pressure

change of at least 25% of the piping operating

pressure range.

Low load measurement- the load is lowered to

70% of full load. This is done especially to

monitor piping with high noise background,

which will assist in filtering it.

Data Analysis


OP Conditions

Continuous Burst

Linear

Location

2D-3D

Location Data Normalizing

Signals Location

Noise Separation

Signals

Classification

History

Severity

Classification

AE Data

Data Analysis


3σ

a

b


Data Analysis

Applicability To P22

• Bench test P22 correlation strain v AE v time

– Transition point occurs at ½ life

– Transition correlates to 1st QAE increase

– Strong correlation


Applicability To P22


Applicability

• For both P91 and P22 – QAE can detect and accumulate energy trend

• Anticipate failure and location of failure

• Highlights use as a PdM tool to reduce risk

• P91 reacts differently to strain than P22 – More sudden failure

• Supports even a greater need for use on P91


Creep Processes

emit Energy

Deformation

Stress Waves

Elongation

(Strain)

AE Signal

(Energy)

Correlation

Applicability

Detectable by

QAE NDI and UT

Detection by

QAE NDI 2 1

3

4

Detection by

QAE NDI

AE Is Emitted As Creep Accumulates

Creep Damage Accumulation Diagram

* Under normal

background noise

conditions

Case Studies

• Case study 1 MS line

– System installed on MS line IN 2004

– No special events reported until 2009 • Inspection reported abnormal activity in section leading to

turbine leads

– During 2011 outage, client performed NDE • Cracks and creep were found


Case Studies


2006

2007

2009

Case study 1 MS line

Case Studies



February 2006 and 2007

January 2009

Case Studies



Creep 5 Creep 3 Creep 2

UT, MT and replica in 2011

Case Studies


Feb 2003 Oct 2003 July 2006 2 days

later

Baseline QAE MC

1st TMI QAE Increased

Activity

TMI- Trend monitoring Inspection

MC- Micro-Cracking

MT- Magnetic Particles Inspection

LPA- Linear Phased Array

NRI- No Reportable Indications

MT LPA NRI

Feb 2005

2nd TMI QAE Increased

Activity

Leak In weld

14

2x40’’ Thermal

Fatigue cracks

Fatigue Crack

Crack identified by LPA in 2006

Case study 2 CRH line: thermal shock / fatigue

Case Studies


Case study 2 CRH line: thermal shock / fatigue

DHAVAN33 Dynegy. Havana. Unit6. CR points 1-20 Eng3SN + 10,Avg48

0

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Point

Hits

Feb. 2003 CS Feb. 2005 CS March. 08 CS

Feb 2003

Feb 2005

Feb 2008 After line repair

Fatigue Crack

Intensive AE activity in 2003 and 2005. The activity decreased after elbow replacement and repairs (2008)

Crack identified by LPA in 2006

AE

Act

ivit

y

14 15

Case Studies


2004 - Two areas were recommended by QAE NDI to be inspected by localized NDE methods due to indications of micro-cracking and creep development.

2005 - Top area: creep class 3 was revealed by replica several indications were revealed by UT. Surface cracks were revealed by MT and grind out.

Bottom area: creep class 4 was verified by replica investigation.

Linear Phased Array Ultrasonic Examination revealed accumulation of multiple processing indications.

Case study 3A HRH line

Case Studies


Company 2 Company 1

Class 1 creep 7/12, Class 2 creep 5/12 Class 3 creep 2/2* Zone 1

Class 1 creep 3/12, Class 2 creep 9/12 Class 4 creep 2/2 Zone 2

Re-inspect in 8-10 years. Repair in six months to one year time period.

Recommend

Replica investigation at girth welds located at zones between AE

points 44-45-50 and 51-52.

Zone 1

Zone 2

Case studies 3A and 3B HRH line

Case studies 3A and 3B HRH line

Case Studies


Company 2; creep class 2 Company 1; creep class 4

Case Studies

• Case study 4 hanger assessment

– In 2000 Unusual AE Activity Noted

– Activity Increased 6-Months Later

– Visual Inspection • Rigid Hangers

• Hanger Repaired


Margan Provides Hanger Assessment With Each Report


Case Studies

• Case study 5 thermal shock

– Thermal shock zone is increasing

– With time and as more

– Attemperation is applied

Start of intensive AE activity when attemperator opening is above 40%.

January 2009

Attemperator valve opening [%]

Piping area subjected to thermal shock/overstresses between

0-30% AE points 8-14

30-40 AE points 6-16

>40 AE points 1-19

Case Studies

• Case study 5 thermal shock

– Thermal shock zone is increasing

– With time and as more

– Attemperation is applied


Start of intensive AE activity when attemperator opening is above 20%.

January 2010

Attemperator valve opening [%]

Piping area subjected to thermal shock/overstresses between

0-20 AE points 8-13

>20 AE points 1-19

Case Studies

• Case study 6 new install economics

– Probability of failure <1%, but consequences very high

– After 10 years only about 21% of the HEP inspected • QAE would provide 100% coverage more frequently

– Cost from traditional NDE on 100% of MS, CHR, and hrhline equaled ~$1.9 million / unit (excluding any asbestos)


Insulation

Remove &

Reinstall

Scaffolding Local NDE $1.9M

Case Studies

• Case study 6 new install economics

– Unit had to be off line to complete traditional NDE

• Replacement power could add to $1.9 million cost

– QAE capital had <3 year payback • Would provide 100% coverage every 2 to 3 years

• Would help prioritize NDE on higher risk areas

• Required less scaffolding and insulation removal


Summary

• QAE NDI is:

– A PdM monitoring and trending program and

– A RCM diagnostic and screening tool

• QAE is a part of a comprehensive HEP inspection program

• QAE can differentiate between various acoustic signatures

Summary

• QAE works on both P22 and P91

• QAE reduces overall risk

• QAE helps to target and prioritize higher risk areas

• QAE supplements traditional NDE

• QAE is cost effective – QAE facilitates outage planning and budget process

Objective

When To Use QAE?

How And Where Does QAE Work?

Why Use QAE As Part Of A Comprehensive Inspection

Program?

What Is QAE?

quantitative acoustic emission (qae)

Documents