04/08/2023 MPEG711 - Defect Assessment/Maintenance in Pipelines -I

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Assessment of

Dents, Cracks & Gouges

Presented To

Mr. P. K. Bahl

University of Petroleum and Energy Studies

Presented By

V. AnandAbhishek Singh

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Assessment of Dents, Cracks & Gouges

Scope of the Presentation

This presentation will give us a basic idea on

• Definitions of Dents, Cracks and Gouges

• Measurement & Assessment Methods

• Repairing Techniques

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Assessment of Dents, Cracks & Gouges

DefinitionsDent

A local depression in the pipe surface caused by mechanical damage that produces a gross disturbance in the curvature of the pipe without reduction in the pipe wall thickness.

CrackTo break without complete separation of parts; fissure

GougeLocal damage caused by mechanical or forceful removal of metal from a local

area on the surface of the pipe that may work harden the pipe and make it more susceptible to cracking.

.

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Assessment of Dents, Cracks & Gouges

Dents – Pics

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Assessment of Dents, Cracks & Gouges

Cracks – Pics

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Assessment of Dents, Cracks & Gouges

Gouges – Pics

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Assessment of Dents, Cracks & Gouges

GOUGE AND DENT WITH AN ASSOCIATED CRACK.

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Assessment of Dents, Cracks & Gouges

Dents – Caused by

Third Party Improper Trench Bed Preparation (presence of rocks) Improper BackfillingEarth Movements Improper Handling of Pipes

Gouges – Caused by

Third Party Improper Handling of Pipe

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Assessment of Dents, Cracks & Gouges

Cracks - Types

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Assessment of Dents, Cracks & Gouges

Scratches and Gouges on pipes must be measured to determine how much material has been removed, and thus, how much of the wall is remaining. Depth micrometers and other mechanical devices cannot provide meaningful measurements because of the contour of the surfaces and the small features that have to be measured. Optical Micrometers also are used to measure dents and gouges along with Laser Gauges.

Dents and Gouges – Assessment & Measurement

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Assessment of Dents, Cracks & Gouges

*Shown: Optical Micrometer Kit (Model 966A1) –Includes 5x and 10x interchangeable optics, 20x eyepiece cell, reticule eyepiece cell; five additional bases, micrometer light, adjustable light bracket and case.

Laser Gauge

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Assessment of Dents, Cracks & Gouges

Laser Gauge

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Assessment of Dents, Cracks & Gouges

The depth (Min) of a scratch is measured from its deepest point relative to a line-fit of the two adjacent surfaces. Material pushed out of the scratch and creating a surface point above the line-fit is also measured (Max).

Edges of the scratch are determined using an edge tolerance provided by the operator and the width is measured between the two edges. Reflectivity problems may occur with scratches narrower than 0.020".

The Laser Gauge algorithm automatically calculates the depth and width of the feature relative to a line-fit of the adjacent surfaces. Adjacent surfaces can be flat or curved. Material that has been pushed up above the original surface can also be measured.

Measurement Using Laser Gauge

Gouge Measurement

Scratch Measurement

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Assessment of Dents, Cracks & Gouges

Inline Inspection –

PIGS – In Measuring and Assessment

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Assessment of Dents, Cracks & Gouges

Intelligent Inspection Pigs are of mainly two types

1) Ultrasonic Type

2) Magnetic Flux Leakage (MFL)

a) Longitudinal b) Transverse

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Assessment of Dents, Cracks & Gouges

Magnetic field is induced in specimen

•Field must be strong enough to saturate the specimen.

•Flaw locally disrupts flux lines causing “leakage” of magnetic flux out of the specimen.

MFL - LEAKAGE

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Assessment of Dents, Cracks & Gouges

Field Orientation and Flaw Detection

Longitudinal field

–Parallel to axis of part

Circular (transverse) field–Circumferentially to axis

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Assessment of Dents, Cracks & Gouges

Flaw orientation in MFL•Magnetic field vs defect orientation plays an important part in flaw detection

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Assessment of Dents, Cracks & Gouges

Data Collection

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Assessment of Dents, Cracks & Gouges

Intelligent Pig - Ultrasonic Type

To Measure Wall Thickness

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Crack Detection

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Assessment of Dents, Cracks & Gouges

ILI Output on a Software Application

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Assessment of Dents, Cracks & Gouges

ILI Output on a Software Application

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Assessment of Dents, Cracks & Gouges

Disadvantages of MFLSizing accuracies have wide tolerances–Depth +/-10%, with an 80% confidence level–Length +/-05”, with an 80% confidence level

Advantages of MFL •Most robust technology for inspecting pipelines •Can be used in gas or liquid pipelines •Can see other metallic objects close to the pipe

such as casings, other pipelines and trench trash

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Assessment of Dents, Cracks & Gouges

Ultrasonic Advantages

•Direct measurement of wall thickness •Metal loss quantification is more accurate than MFL •Detects “mid-wall”anomalies such as laminations

Ultrasonic Disadvantages

•Requires Liquid medium •Very clean line

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Assessment of Dents, Cracks & Gouges

Thank You !