Introduction and background to DNV RP-F101 "Corroded Pipelines"

In this paper an introduction and background to the new DNV RP-F101 "Corroded Pipelines" is given. The RP (Recommended Practice) gives recommendations for the assessment of corroded pipelines subject to internal pressure, and internal pressure combined with longitudinal compressive stresses and covers single defects, interacting defects and complex shaped defects. The RP is a result of a co-operation between BG Technology and DNV. The results from their respective joist industry projects have been merged, and form the technical basis for RP-F101. Several oil companies and regulating authorities have sponsored the development of the RP. RP-F101 describes two alternative approaches with different safety philosophy for the assessment of corrosion in pipelines. The first approach is in accordance with the safety philosophy adopted in the DNV Offshore Pipeline Standard (DNV OS-F101). Uncertainties associated with the sizing of the defect and the material properties are specifically considered in determination of the allowable operating pressure. The second approach is based on the allowable stress design format, where the allowable operating pressure is determined from the capacity and multiplied with a single usage factor based on the original design factor. In this paper, focus is on the single defect in the first approach, being in accordance to the safety philosophy adopted in the DNV Offshore Standard OS-F101. The burst capacity equation is described, and the acceptance equation, the calibration of partial safety factors, and an example are given.