INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
artículos
Título:
Experimental determination of Stress Corrosion Crack Rates and service lives in a Buried E.R.W. Pipeline
Autor/es:
P.G. FAZZINI,; J.L. OTEGUI
Revista:
INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING
Editorial:
Elsevier
Referencias:
Año: 2007 vol. 84 p. 739 - 748
ISSN:
0308-0161
Resumen:
Threshold stresses and crack growth rates for in-service stress corrosion cracking (SCC) of two electrical resistance weld (ERW) seam
welded pipes from two 45-year-old oil pipelines were experimentally assessed. Seventeen high-pH SCC tests were carried out, in both base
and ERW weld metals, at two temperatures (73 and 45 1C). Tapered specimens were used for base metal, and constant section specimens
were developed for ERW tests, in which original surface conditions were preserved. It was found that susceptibility of the ERW seam
welds is much higher than for base materials, so that the welds define the length of the pipe that is susceptible to SCC. Threshold pressure
estimates for SCC initiation were defined from tests at elevated temperature, service temperature, and literature correlations. Fabrication
residual stresses were also measured and taken into consideration. SCC threshold pressures for these lines are controlled by the ERW
welds; the pipe tracts that are considered to be susceptible to SCC are those that undergo a service pressure of at least 2.4 MPa. For the
case under study, this represents about 70% of the length of the pipeline.1C). Tapered specimens were used for base metal, and constant section specimens
were developed for ERW tests, in which original surface conditions were preserved. It was found that susceptibility of the ERW seam
welds is much higher than for base materials, so that the welds define the length of the pipe that is susceptible to SCC. Threshold pressure
estimates for SCC initiation were defined from tests at elevated temperature, service temperature, and literature correlations. Fabrication
residual stresses were also measured and taken into consideration. SCC threshold pressures for these lines are controlled by the ERW
welds; the pipe tracts that are considered to be susceptible to SCC are those that undergo a service pressure of at least 2.4 MPa. For the
case under study, this represents about 70% of the length of the pipeline.