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SEMINAR PRESENTATIONON

CRACK DETECTION IN PIPES

UNDER THE GUIDANCE OF

MR. A. V. DEOKARPRESENTED BY

AKANSHA JHADEPARTMENT OF MECHANICAL ENGINEERING

AMRUTVAHINI COLLEGE OF ENGINEERING, SANGAMNER2011-2012

T.E MECHANICAL SEMINAR

MAIN POINTS TO BE DISCUSSEDINTRODUCTION

TYPES OF CRACK

CAUSES AND EFFECTS

METHODS OF CRACK DETECTION

NATURAL FREQUENCY BASED METHOD

CONCLUSION

BIBLIOGRAPHY

22. SEPT. 2011 AKANSHA JHA 2/22

INTRODUCTION TO CRACK

• Definition “Any deviation introduced to a structure, either deliberately or

unintentionally, which adversely affect the performance of the system.”

Damage Assessment

Four levels of damage assessment:

1. Determining the presence

2. Locating the damage

3. Quantifying the severity

4. Prediction of the remaining serviceability



CAUSES OF CRACK EFFECTS OF CRACK

Mechanical Damage

Material Defects

Weld Cracks

Incomplete Fusion

Incomplete Penetration

Fatigue Cracks

External Or Internal Corrosion

Hydrogen Blistering

High production and

maintenance Cost

Leads to Catastrophic Failure

Operational Problem

Premature Failure

Affects the Industrial Economic Growth.



1) Transverse cracks : Cracks perpendicular to the pipe axis are known as “transverse cracks”


TYPES OF CRACK


2) Longitudinal cracks: Cracks parallel to the pipe axis are known as “longitudinal cracks”.


TYPES OF CRACK


3) Slant cracks: cracks at an angle to the pipe axis are known as “Slant cracks”


TYPES OF CRACK


TYPES OF CRACK

4) Gaping cracks: Cracks that always remain open are known as “gaping cracks” or “notches”.

5)Surface cracks: Cracks that open on the surface are called “surface cracks”.

6)Subsurface cracks: Cracks that do not show on the surface are called “subsurface cracks”.


22. SEPT. 2011 AKANSHA JHA 7822

CONVENTIONAL METHODS :

(Non- Destructive techniques)1. Pipeline injection gauze

2. Sewer scanner & evaluation technology

3. Automated pipe crack detection

4. Ultrasound acoustics based assessment technique

NON-CONVENTIONAL METHOD :• Natural Frequency


METHODS OF CRACK DETECTION


CONVENTIONAL METHODS

1) Pipeline Injection Gauze(PIG) :‘Smart’ and Intelligent inline inspection tools sent through the pipe via the circulation of fluid.

Fully automatic Data stored on solid state memoriesReliable in a hostile environmentCannot be supervised during a runThe inspection speed depends on the medium



2) Sewer Scanner & Evaluation Technology(SSET) :

Technology for obtaining images of the interior of pipe

It can travel through the pipe at a uniform speed

Higher quality image data

Enables us to make critical rehabilitation decisions.




3) Automated Pipe Crack Detection :Successfully able to detect cracks in varying pipe backgrounds, colour, and crack patterns.

Better 2-D features from segmented crack images are available




DATA OF UNCRACKED PIPE(l=900 mm, di=16 mm, do=21 mm

EXPERIMENTAL DATA OF 1st PIPE(300 mm from one end for d=1 mm and d=2 mm)


Analytical Experimental FE modelω1

(Hz) 146.9 147.50 146.54

ω2 (Hz) 404.98 399.63 401.69

ω3 (Hz) 793.95 786.75 787.17

Depth=1mm Depth=2mmω1

(Hz) 147.25 147.0

ω2 (Hz) 398.63 397.75

ω3 (Hz) 786.63 786.38

NATURAL FREQUENCY AS BASIC CRITERION




x-coordinate : Normalized distance of the crack (x/l) where, x= crack location l=length of pipey-coordinate: Crack dimensions(d/w) where ,d= depth of crack w=width of pipez-coordinate: Natural frequency










FE results Experimentalω1

(Hz) 1084.2 1083.5

ω2 (Hz) 1413.0 1411.1

ω3 (Hz) 1659.4 1658.1

DATA OF UNCRACKED PIPE(l=650 mm, do =104.5 mm, di=112.5 mm

EXPERIMENTAL DATA OF 2nd PIPE(325 mm from one end for d=1.5 mm)

depth=1.5mmω1

(Hz) 1077.6

ω2 (Hz) 1412.0

ω3 (Hz) 1652.3






Significant changes in natural frequencies of the vibrating pipes are observed at the vicinity of crack location.

With the increase in crack depth, the natural frequency of the pipe decreases

The less is the wall thickness, less is the computational effort

This method is promising and can be used over a large-scale ,compared to other NDE techniques.

CONCLUSION:



“Material Science And Metallurgy”; V.D.Kodgire and S.V Kodgire; Everest Publishing House; 25th Edition.

“Crack Location In Pipes Using Modal Frequencies And Fem”; M.J. Mahboob, A. Marzban and A.Shahsavri; The 11th International Conference On Vibration Engineering, Timissoara, Romania, 2005.

“Crack Detection In Aluminum Structures”; Brad A. Butrym, M.S. Thesis; Virginia Polytechnic Institute And State University; 2010.

“Vibration Analysis Of Cracked Beam”; Prabhakar M.S, Thesis Of M. Tech; National Institute Of Technology, Rourkela; 2009.


QUESTIONS?



THANK YOU

