Finally, support and component reliabilities were evaluated based on available fragility data. An investigation of the malfunction of pipe whip restraints confirmed that the malfunction introduced higher thermal stresses and tended to reduce the overall piping reliability. Furthermore, the more flexible piping redesigns are capable of exhibiting reliability levels equal to or higher than the original stiffer design.
They concluded that these changes substantially reduce calculated piping responses and allow piping redesigns with significant reduction in number of supports and snubbers without violating ASME code requirements. The authors then investigated a couple of changes to be implemented in Regulatory Guide (RG) 1.61 and RG 1.122 aimed at more flexible piping design. A confirmatory piping reliability assessment indicated that removing rigid supports and snubbers tends to either improve or affect very little the piping reliability. The current study was conducted to establish the necessary groundwork based on the piping reliability analysis. The overall objective of this research project is to develop a technical basis for flexible piping designs which will improve piping reliability and minimize the use of pipe supports, snubbers, and pipe whip restraints. International Nuclear Information System (INIS) Reliability analysis of stiff versus flexible piping Subsequent tensile tests of the tested specimens at ambient pressure and temperature have revealed properties similar to the as-received specimens. Examinations of the tested specimens have not revealed cracking or blistering. Simulated tests have been carried out in simulated solution containing high concentration of chloride, with high hydrogen sulphide partial pressure, at high stress level and at 120 Â☌ for 720 hours. In addition, sulphide stress cracking (SSC) and chloride stress cracking (CSC) of nickel-based alloy armour wires used in harsh down-hole environments has been evaluated. Examinations of the tested specimens have not revealed cracking or blistering, and measurement of hydrogen content has confirmed hydrogen charging. at room temperature, at the maximum negative cathodic potential and at the maximum stress level expected in service for 150 hours. Simulated tests have been carried out in simulated sea water, under conditions where the susceptibility is the highest, i.e. Hydrogen induced cracking (HIC) or hydrogen embrittlement (HE) of steel armour wires used in deep-water and ultra-deep-water has been evaluated. Įvaluation of Environmentally Assisted Cracking of Armour Wires in Flexible Pipes, Power Cables and UmbilicalsĮnvironmentally assisted cracking (EAC) of armour wires in flexible pipes, power cables and umbilicals is a major concern with the development of oil and gas fields and wind farms in harsh environments. The safe operating window for the installation is limited by whether induced motion of the installation vessel giving rise to dynamic tension and curvature at the touch-down-zone (TDZ). to a flow-line/sea floor installation or similar. Flexible pipes are mostly used to transport fluids between platforms/ships etc. Torsion instability of Flexible Pipes at the TDP - Torsjonsinstabilitet av fleksible rør med sjøbunnskontaktĭynamic flexible risers are a common term for cables, umbilicals and flexible pipes,that are freely or semi-freely suspended between two points (offshore).