Statistical Analysis on Underload-Type Pipeline Spectra

In this investigation, analyses of pressure fluctuations during oil and gas pipeline operations are performed. The analyses are performed in a way to capture all the variables of pressure fluctuations and their magnitudes in terms of crack growth rate. It is found that pipeline spectra can be categorized into three main types: underload-dominant, mean load-dominant, and overload-dominant spectra, depending on their locations with respect to a compressor or pump station. The underload spectra—typical of pressure fluctuations at the discharging sites—are the most severe in terms of crack growth as these spectra are subjected to the highest pressure level and the largest magnitude and frequency of pressure fluctuations. The underload spectra are further analyzed in terms of loading and unloading frequency, maximum stress-intensity factor, stress-intensity factor range, numbers of minor cycles between two adjacent underloads, and their potential for crack growth. Special attention is paid to the difference between oil and gas pipeline spectra. The frequency of pressure fluctuations is found to vary over a much wider range during oil pipeline operation than during gas pipeline operation, and the occurrence of crack growth contributing loading events is significantly more frequent in oil pipeline spectra than in gas pipeline spectra. It is recommended that the supervisory control and data acquisition (SCADA data) is recorded at a minute rate for gas pipelines and at a second rate for oil pipelines in order to capture most crack-growth-contributing events of pressure fluctuations during pipeline operation.

Language

  • English

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Filing Info

  • Accession Number: 01599644
  • Record Type: Publication
  • Files: TRIS, ASCE
  • Created Date: Apr 28 2016 3:03PM