Guidelines for Inspection of In-plant Buried Process Piping

Authors:

Tony Kakpovbia Ph.D.

Randy Vander Voort

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API 570 Framework, Inspection Planning, Frequency and Extent of Inspections, Methods of Inspection, Excavation, Repairs and Records, Summary and Benefits.

Scope of Presentation

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API 570 Framework

Section 9 of API 570 recognizes two distinctions regarding buried pipe: Significant External Deterioration, Inaccessibility.

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API 570 Framework

Subsections of Section 9 are: Types and Methods of Inspection.

Direct and indirect monitoring (limited reference). Frequency and Extent of Inspection. Repairs to Buried Piping System. Records.

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Inspection Planning

Process Hazard Analysis (PHA) issues: Analysis by one of:

Hazards & Operability Analysis (HAZOP), Failure Mode & Effects Analysis (FMEA), Fault Tree Analysis.

MSDS review and regular safety training. Complete, review, approve and regularly update

Management of Change (MOC) documentation.

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Inspection Planning

Complete periodic qualitative evaluation of risk on the likelihood versus consequences grid basis.

Complete quantitative risk assessment, if possible.

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Inspection Planning

Analysis of Generated Inspection Data

Pre-installation (baseline) risk assessment: Complete PHA, personnel training, Review plant operations & engineering data, Establish and approve MOC plan, Estimate potential operating life, Establish inspection intervals.

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Inspection Planning

Analysis of Generated Inspection Data

Operating: Annual inspections data review, CP System performance review, Review pipe internal inspection data, Complete RBI evaluation – minimally qualitative,

preferably including quantitative, Update MOC plan, Determine remaining life, Update inspection interval.

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Inspection Planning

Inspection Methods

Direct Techniques: Measurement of metal loss or corrosion rate, Intrusive, Non-intrusive.

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Inspection Planning

Inspection Methods

Indirect Techniques: Measurement of parameters that may

influence or are influenced by metal loss. Surface technologies, On-line, Off-line.

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Leak Detection

Visual: Surface contour, Discoloration of soil, Softening of the surface, Pooling, bubbling, poor drainage, Odor.

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Leak Detection

Thermography: Identify leaks that travel to surface.

Tracer Detection: Tracer Chemicals – add to process, Helium Gas – offline.

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Excavations

Hand Excavation: Within a few inches.

Mechanical Excavation: Back hoe, Gradall.

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Excavations

Hydrovac Excavation: “Day lighting”, Nondestructive, Minimal soil removal. Frozen ground, No source of ignition.

Hydrovac excavation is not foolproof.

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Excavations

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Inspection Methods - Surface

Indirect: Non-Intrusive: Visual Surveillance, Leak Testing, Close Interval Potential Survey, Soil Resistivity – high resistance soils require

lower CP current, Cathodic Protection (CP) Monitoring.

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Inspection Methods - Surface

Direct: Intrusive: Intelligent pigging,

MFL, UT, RFT, Remote Visual

Inspection. Guided Wave

Ultrasonic Testing.

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Guided Wave Ultrasonic

What is Guided Wave Ultrasonic Testing? A sonic technique using torsional and

longitudinal waves. Sensitive to ID and OD wall losses. Up to 48” diameter.

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Guided Wave Ultrasonic

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Guided Wave Ultrasonic

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Guided Wave Ultrasonic

Results

A typical weld is completely symmetric and shows up as only a black curve.

A typical corrosion patch is non-symmetric and is identified by the presence of a red curve.

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Guided Wave Ultrasonic

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Guided Wave Ultrasonics

Advantages: Full circumferential data, Non-intrusive, on-line and off-line, Up to 4,000 feet per day, Use on lined, coated, insulated or buried pipe, Portable, Repeatable results.

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Guided Wave Ultrasonics

Disadvantages: Buried pipe dampens signal (30 meters).

Concrete lining, Coatings, Wrapping.

Placement on pipe critical. Pipe configuration critical. Not quantitative data; sorting tool only. Follow-up with direct inspection required.

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Inspection Methods - Below Grade

Direct - Non-Intrusive: Pipe Coating Holding Survey, Ultrasonic Corrosion Survey, Radiography – profile shots, MT/PT,

Surface Profile Mapping, Pitting,

Manual,Computerized (Laser Pro).

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Inspection Methods - Below Grade

Direct - Intrusive: Pipe Sample/cut out collection, Intelligent Pigging,

MFL, UT, RFT.

Video Camera.

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Intelligent Pigging

Magnetic flux leakage. Ultrasonic. Remote Field Eddy Current.

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Video Camera

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Repairs: As per B31.3, As per Section 8.2 of API 570.

Records: Permanent and progressive, Inspection results, CR, repair history.

Repairs and Records to Buried Pipe

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Summary

Buried pipe needs an assessment and inspection program like any process plant piping.

Don’t fall into “out of sight, out of mind”. Must address with both internal and external

metal loss. Indirect techniques help with risk

ranking/inspection planning.

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Summary

Cathodic Protection has many benefits: Minimizing soil side corrosion, Thinner walled pipe, less C.A., Increased inspection intervals.

GWUT is emerging as a powerful tool for sorting purposes.

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Summary

Intelligent pigging is becoming more process plant friendly.

Excavation should be a last resort; controls for safety and coating damage of major importance.

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Acknowledgements

Ken Izer, Chevron, California. Tim Ryan, GE Inspection Technologies, Alberta. Dave Russell, Russell Technologies, Alberta. Larry Martin, formerly of Acuren, Alberta.