Todd KedzieTodd KedzieEl Paso Corporation El Paso Corporation

Manager of Laboratory ServicesManager of Laboratory Services

Bell Hole Inspection Techniques for Bell Hole Inspection Techniques for Assessing SCC SeverityAssessing SCC Severity

December 2, 2003December 2, 2003

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IntroductionIntroduction

Magnetic Particle Inspection (MPI) Magnetic Particle Inspection (MPI) TechniquesTechniques

SCC Depth Measurement by GrindingSCC Depth Measurement by Grinding

SCC Depth Measurement Technology SCC Depth Measurement Technology ResearchResearch

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Magnetic Particle Inspection (MPI)Magnetic Particle Inspection (MPI)

MPI is an NDE method of inspection that uses fine MPI is an NDE method of inspection that uses fine magnetic particles (iron) that are applied to the part, and magnetic particles (iron) that are applied to the part, and are attracted to any magnetic-leakage field created by an are attracted to any magnetic-leakage field created by an imperfection, such as SCCimperfection, such as SCC

Magnetic yokes are commonly used for bell hole MPI of Magnetic yokes are commonly used for bell hole MPI of pipelinespipelines

Each MPI method discussed is capable of detecting Each MPI method discussed is capable of detecting SCC, depending on field and pipeline operating SCC, depending on field and pipeline operating conditionsconditions

No single MPI method is effective in all situations, No single MPI method is effective in all situations, therefore several methods must be available to choose therefore several methods must be available to choose fromfrom

MPI can be performed at all clock positionsMPI can be performed at all clock positions

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Dry MPIDry MPI

Description: Dry MPI uses fine iron particles that Description: Dry MPI uses fine iron particles that are not suspended in a liquid. The iron particles are not suspended in a liquid. The iron particles are blown onto the pipe surface using a bulb or are blown onto the pipe surface using a bulb or

powder blower applicator. Iron particles are powder blower applicator. Iron particles are available in a variety of colors to obtain contrast available in a variety of colors to obtain contrast

with the pipe surfacewith the pipe surface

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Dry MPIDry MPI

LimitationsLimitations– Dry MPI method is not suitable for use when the Dry MPI method is not suitable for use when the

pipe surface is wet (sweating, rain, etc.)pipe surface is wet (sweating, rain, etc.)

– Least sensitive method of MPILeast sensitive method of MPI

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Wet Fluorescent MPIWet Fluorescent MPI

Description: Wet Fluorescent MPI uses fine Description: Wet Fluorescent MPI uses fine iron particles that are suspended in a liquid iron particles that are suspended in a liquid (water or hydrocarbon). The iron particle (water or hydrocarbon). The iron particle

suspension liquid is sprayed onto the pipe suspension liquid is sprayed onto the pipe surface. The iron particles fluoresce in the surface. The iron particles fluoresce in the dark when illuminated with a black light dark when illuminated with a black light

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Wet Fluorescent MPIWet Fluorescent MPI

LimitationsLimitations– Hydrocarbon suspension can result in a cloudy Hydrocarbon suspension can result in a cloudy

fluorescent background that can reduce the contrast fluorescent background that can reduce the contrast between the indications and the background when between the indications and the background when inspecting coal tar coated pipelinesinspecting coal tar coated pipelines

– Requires dark background often provided by a tarp or Requires dark background often provided by a tarp or tent for black light usetent for black light use

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Wet Visible MPIWet Visible MPI

Description: Wet visible MPI uses fine iron Description: Wet visible MPI uses fine iron particles that are suspended in a liquid particles that are suspended in a liquid (water or hydrocarbon). The iron particle (water or hydrocarbon). The iron particle suspension liquid is sprayed onto the pipe suspension liquid is sprayed onto the pipe surface. The iron particles are visible, and do surface. The iron particles are visible, and do not require black light illumination not require black light illumination

LimitationsLimitations– Limited variety of colors for contrastLimited variety of colors for contrast

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Black and White Contrast MPIBlack and White Contrast MPI

Description: Contrast MPI uses fine iron particles that are Description: Contrast MPI uses fine iron particles that are suspended in a liquid (hydrocarbon) that is sprayed onto suspended in a liquid (hydrocarbon) that is sprayed onto the pipe surface. The surface of the pipe is painted prior the pipe surface. The surface of the pipe is painted prior to application of MPI in order to provide contrast with the to application of MPI in order to provide contrast with the visible iron particles visible iron particles

LimitationsLimitations– Greater surface cleanliness required for white paint Greater surface cleanliness required for white paint

applicationapplication

– Contrast paint may increase the clean up timeContrast paint may increase the clean up time

Grinding Method to DetermineGrinding Method to DetermineSCC DepthSCC Depth

Description: The population of SCC indications are Description: The population of SCC indications are assessed, and grinding is performed on selected assessed, and grinding is performed on selected indications. MPI is performed, and the depth of the indications. MPI is performed, and the depth of the SCC is measured when the indication has been SCC is measured when the indication has been removedremoved

LimitationsLimitations– Depth is only determinedDepth is only determined

for those indications chosenfor those indications chosenfor examinationfor examination

– Grinding on loaded lines mustGrinding on loaded lines mustbe performed cautiouslybe performed cautiously(see PRCI Pipeline Repair(see PRCI Pipeline RepairManual for additionalManual for additionalinformation)information)

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SCC Depth Measurement ResearchSCC Depth Measurement Research

Description: Technologies from 16 companies Description: Technologies from 16 companies were evaluated for SCC depth measurementwere evaluated for SCC depth measurement

Technical Challenge: Accurately measuring the Technical Challenge: Accurately measuring the deepest crack within a colony using NDE from deepest crack within a colony using NDE from the same side as the crackingthe same side as the cracking

3 general types of technologies were studied3 general types of technologies were studied– Ultrasonic based methodsUltrasonic based methods

– Electromagnetic methodsElectromagnetic methods

– Electromagnetic acoustic transducer methodsElectromagnetic acoustic transducer methods

PR-003-9718PR-003-9718

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SCC Depth Measurement ResearchSCC Depth Measurement Research

Techniques were evaluated with Techniques were evaluated with the following criteria:the following criteria:

– Accurate depth measurement Accurate depth measurement for near-critical flawsfor near-critical flaws

– Accurate depth measurement Accurate depth measurement for sub-critical flawsfor sub-critical flaws

– Accurate discrimination of Accurate discrimination of inconsequential cracks from inconsequential cracks from cracks that may grow to failure cracks that may grow to failure though fatigue mechanismthough fatigue mechanism

PR-003-9718PR-003-9718

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SCC Depth Measurement ResearchSCC Depth Measurement Research

Results of research: Results of research:

– None of the techniques completely met the goal of a None of the techniques completely met the goal of a simple, low cost, operator independent sizing techniquesimple, low cost, operator independent sizing technique

– Ultrasonic techniques were found to have the greatest Ultrasonic techniques were found to have the greatest potential for sizing SCCpotential for sizing SCC

– Most successful techniques were:Most successful techniques were:

Ultrasonic Time of Flight Diffraction (TOFD)Ultrasonic Time of Flight Diffraction (TOFD)

Ultrasonic Phased Array. Note: This method provided a 3-Ultrasonic Phased Array. Note: This method provided a 3-dimensional examination of the cracksdimensional examination of the cracks

Electromagnetic methods were found to consistently under Electromagnetic methods were found to consistently under estimate the crack depths. Improved technology, calibration estimate the crack depths. Improved technology, calibration methods, and cleaning procedures will be required for this methods, and cleaning procedures will be required for this method to become usefulmethod to become useful

PR-003-9718PR-003-9718

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Current SCC Depth Measurement Current SCC Depth Measurement ResearchResearch

Research program: Research program: – Application of phased array UT Application of phased array UT

characterization in the fieldcharacterization in the field

GRI 8122GRI 8122

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Concluding RemarksConcluding Remarks

Current bell hole inspection techniques Current bell hole inspection techniques utilize MPI and grinding to determine SCC utilize MPI and grinding to determine SCC depth, length, orientation, and clock positiondepth, length, orientation, and clock position

More advanced inspection methods have More advanced inspection methods have been evaluated, but none of these methods been evaluated, but none of these methods have proven to be capable of accurately have proven to be capable of accurately measuring SCC depthmeasuring SCC depth

Most promising technologies (phased array Most promising technologies (phased array UT characterization) are currently being UT characterization) are currently being evaluatedevaluated

Todd KedzieTodd KedzieEl Paso Corporation El Paso Corporation

Manager of Laboratory ServicesManager of Laboratory Services

Bell Hole Inspection Techniques for Bell Hole Inspection Techniques for Assessing SCC SeverityAssessing SCC Severity

December 2, 2003December 2, 2003