OPS - SCC Workshop R&D Past and Present

December 2, 2003

Jerry Rau - Panhandle Energy

Outline

1. Review of past R&D accomplishments

2. Recent and current SCC R&D efforts

The History

1965 Identified SCC as a possible cause of pipeline failures

1965 - 1970 SCC identified as an industry-wide concern, not an

isolated incident

Early Research

1966 - 1968 Carbonate/bicarbonate environments existed at

locations of high-pH SCC A carbonate/bicarbonate environment could cause SCC

of a carbon steel

1966 - 1970

Reproduced high-pH SCC in the laboratory

Research on the Stress Component

1975 - 1983 Thorough cleaning of the pipe surface to remove mill scale

prior to coating should significantly reduce the probability of high-pH SCC

1980 - 1984 Developed a method to determine the threshold stress for

SCC in a single test with a single (tapered) specimen

1973 - 1983 Discovered that low-frequency, low-amplitude stress

fluctuations could reduce the threshold stress considerably

Material Issues

1970 - 1980

Showed that there is no direct correlation between the

grade of pipe (for X46 through X80) and its

susceptibility to high-pH SCC (1970-1980)

1973 - 1981

Shot peening and grit blasting can significantly

increase the resistance of a pipe to SCC

Temperature Issues

1968 - 1975

Demonstrated that lower discharge temperatures can

have a substantial beneficial effect on reducing the

probability of a failure due to high-pH SCC. Results in much lower crack growth rates

Results in narrower range of environmental conditions that will

support SCC

Slower deterioration of coatings

Mitigation Issues

1975 - 1995 Periodic hydrostatic retesting is an effective way to assure

the integrity of a pipeline that may have stress-corrosion

cracks

1972 - 2002

Developed a life-prediction model for high-pH SCC that

enables a pipeline operator to evaluate the significance of

cracks that are discovered and adequately sized.

Environmental Issues

1977

Discovered that relatively dilute groundwater containing

CO2 could cause transgranular (near-neutral-pH) SCC

1977 - 1987

Determined that near-neutral-pH SCC occurs only in areas

where little, if any, cathodic-protection current reaches the

steel

1980-2000

Determined that stress fluctuations are critical with near-neutral-pH SCC as well as with high-pH SCC

Prioritizing Areas to Inspect for SCC

1977 - 2002

Guidelines developed for improving the cost effectiveness

of hydrostatic retesting, in-line inspections, and bellhole

inspections.

Based upon proximity to other SCC locations, coating

type, geology, soil type, temperature history, and pressure

history

Managing SCC

1965 - 2000

A practical way to manage the SCC problem (both high-

pH and near neutral-pH) for future pipelines The coating and

The condition of the pipe surface

Eg. The use of fusion-bonded epoxy coatings on

mechanically cleaned surface preparation

R&D Projects in PRCI Materials Committee

SCC Susceptibility

SCC Initiation Susceptibility Ranking/Screening

Review of Stress Corrosion Cracking of Pipelines in Contact with Near-

Neutral (Low) pH Solutions

SCC Crack Growth / Re-inspection Intervals

Growth Model for Assessment after SCC Detection

SCC Crack Growth - Effects of Operating Practices

Effects of Pressure Fluctuations on Near-Neutral SCC Propagation

SCC Crack Extension and Coalescence Modeling

Hydrostatic Testing Frequencies for SCC Control

Field Studies to Support SCC Life Prediction Model

R&D Projects in PRCI Materials Committee

SCC Direct Examination

Application of Phased Array UT Characterization in the Field

Reliable Diagnosis of SCC During Field Inspection

SCC Engineering Critical Assessment

SCC Acceptance Criteria

Model for Assessing Remaining Strength of Line Pipe with Co-

existent Corrosion and SCC

SCC Mitigation & Repair

Permanent Field Repair of SCC

Cyclic Stress/Strain Behavior of Steels for SCC Service

R&D Projects in PRCI C&I Committee

Transforming Shallow Cracks to Significant Cracks

SCC Sample management

Disbonded Tape - EMAT on MFL

Prediction of SCC from Field Measurements

Maps Technology for Stress Measurement

SCCDA Development Support

NLH/Barkhausen

Summary

Research Continuous From 1965

Much has Been Learned

More Still to be Learned