Optimizing ILI Inspection Scheduling

Course objective

This new one-day course presents methods for dealing with inherent uncertainties about corrosion growth rates as well as ILI tool measurements, with the object of improving the reliability of ILI inspections, and the interpretation of the inspection results into maintenance decisions. It examines methods of determining corrosion rates, timing of inspections, and deterministic-, reliability-, and risk-based approaches to dealing with uncertainties and establishing failure criteria. The course is intended for those with basic familiarity with ILI tools and their capabilities.

Course Notes

 All delegates will receive a detailed set of lecture notes providing an invaluable reference document.

Continuing Education Units

Upon completion of the course, participants will be eligible to receive .4 Continuing Education Units (CEUs).

Who should attend

The course is especially designed for pipeline integrity engineers and inspection specialists, ILI data analysts, and technical personnel responsible for pipeline integrity assurance and corrosion control.

Lecturer

Guy Desjardins is president of Desjardins Integrity, a consulting firm in Calgary, AB. He has more than 25 years experience in the oil and gas industry and 12 years with pipelines. In 1997, he became a principal co-owner of Morrison Scientific and became Morrison’s president in 1998. He has been an independent consultant since 2005, offering services of data analysis, research, and software development.

Introduction

• Goals of the course
• ILI inspections scheduling
• Repairs
• Reliability
• Risk
• Cost

Corrosion rates

• Location dependence
  • Variation of corrosion rate with location
• Time dependence
  • Corrosion rate from season to season
  • Year to year
  • Historical rates versus future rate
• Distance scale
  • Gross scale corrosion rate
  • Microscopic
• Time scale

Introduction to Inspection timing

• General problem
• Goals of the solution

Deterministic approach

• General approach
• Dealing with ILI uncertainty
• Dealing with corrosion rate uncertainty
• Setting a failure criteria

Reliability approach

• General approach
• Dealing with ILI uncertainty
  • Assessing ILI accuracy
• Dealing with corrosion rate uncertainty
• Setting a failure criteria
  • Probability of failure (POF)
  • Probability of rupture (POR)
  • Probability of leak (POL)
  • Probability of exceedance (POE)
  • Individual POE versus aggregate POE
    • Pros and cons of the aggregate POE
  • Calibrating POF/POE failure criteria to conventional maintenance methods

Risk approach

• Similarity to Reliability approach
• Setting a failure criteria

Assessing ILI uncertainty

Methods of assessing corrosion rates

• Industry standards
• NACE standard
• API 570 long term rate
• Correlation of anomalies from two (or more) ILI runs
• Environmental correlations
• LPR measurements
• Coupons
• Reducing uncertainty in corrosion rate assessment

Assessment of failure pressure

• B31G
• Rstreng .85dl
• Rstreng effective area
• Other better methods

Miscellaneous Topics

• Conservativeness versus accuracy
• Unknown factors

OPIS Software Tutorial