ASSESSMENT OF DNV-RP-F101 METHOD IN ESTIMATING THE FAILURE PRESSURE IN CORRODED PIPELINES

ALCIANE VARGAS BASSO¹; JOÃO ELIAS ABDALLA FILHO¹; HSU YANG SHANG¹

¹ PONTIFICAL CATHOLIC UNIVERSITY OF PARANA

doi:10.20906/CPS/COB-2015-1863

Resumo

Pipelines are efficient means to transport oil, natural gas, ethanol and derivatives. As they are in direct contact with the soil, buried pipelines may be subjected to corrosion defects. Corrosion is one of the most common causes of pipeline damage. Once the defect has been detected, the associated failure pressure must be evaluated. The objective of this work is to evaluate the degree of conservatism of the method of DNV-RP-F101 code for corroded pipes when subjected to internal pressure for different dimensions of corrosion defects. The adopted methodology estimates the failure pressure for pipes containing wall-reduction corrosion defects. These analytical results are compared to numerical results provided by finite element analyses. In order to validate the numerical model, experimental results provided by Choi et al. (2003) will be used. In that work, seven API-X65 pipes containing wall reduction defects with varying length, width and depth have been burst by internal pressure. Due to its conservativeness, the rectangular geometry has been adopted for the defect, and its variables are length, depth or width. Also, the ASME B31G semi-empirical method has been used to estimate failure pressures of corroded pipes to provide support for the analyses using the DNV method. In general, for long defects, the DNV method provides accurate results when compared to finite element analysis results. However, such results are less conservative than those provided by the ASME B31G. Considering short defects, it appears that results depend on the defect depth. Further investigation is required.

Palavras-chave: Pipelines; Corrosion Defects; DNV-RP-F101 Method; Finite Element Analysis; ASME B31G method