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Anderson T.L.,Quest Integrity Group
PPIM 2012 - 24th Pipeline Pigging and Integrity Management Conference

A discussion on innovative technologies that can be applied to the integrity management of seam-welded pipe, which focuses on cracks and other planar flaw, covers the NG-18 equation for estimating burst pressure and critical flaw size; the modified In-sec equation; API and ASME'S standard that covers fitness-for-service assessment of pressure equipment, including pressure vessels, storage tanks, piping, and pipelines; and PRCI's improved failure model for cracks in longitudinal seam welds. This is an abstract of a paper presented at the Pipeline Pigging & Integrity Management Conference (Houston, TX 2/8-9/2012). Source

The article presents a review of literature which covers aspects of pitting corrosion observed in metallic materials, focussing on events associated with nucleation of pits, i.e. passivity breakdown, initiation of pits and their propagation stage. It is highlighted that there is a clear separation of the passivity breakdown/pit initiation process from the pit propagation, which can be considered in terms of the localised acidification model of Galvele. The process of passivity breakdown is more diverse and remains still the least understood. Relevant appears the recent argument of Burstein about the state of passivity and its continuous process of breakdown and repair. Under such conditions and using the localised acidification as a criterion, the likelihood of stable pits is then only a question of how good the repair process is. © 2014 Elsevier Ltd. Source

Turnquist M.,Quest Integrity Group
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP

This case study exhibits how groundbreaking inspection methodologies combined with innovative computational analysis practices demonstrate the value of conducting fitnessfor-service (FFS) assessments on sectional piping. In this instance, a fitness-for-service assessment was performed on two sections of piping experiencing external corrosion at the pipeto-elbow seam welds. A full external scan and spot ultrasonic thickness (UT) readings were used to create the corroded geometry and verify accurate measurement of the remaining thicknesses in various corroded locations. This allowed for the actual corroded profiles to be accurately modeled using finite element analysis (FEA). Complications were present when modeling the observed metal loss. Through the use of innovative finite element mesh generation practices, the actual measured corroded geometry was modeled without the need for over-conservative geometric simplification. A Level 3 FFS assessment was then performed in addition to a remaining life assessment based on observed corrosion rates. The result of this analysis was that the piping could remain in service for at least two additional years before needing repair. © Copyright 2015 by ASME. Source

Anderson T.L.,Quest Integrity Group
Pipeline and Gas Journal

A sample of innovative technology that can be applied to the integrity management of seam-welded pipe is presented focusing on cracks and other planar flaws. Pipeline Research Council International (PRCI) completed a research project to develop an improved failure model for cracks in longitudinal seam welds. This project consisted of a three-dimensional finite element parametric study, where a range of crack sizes, pipe dimensions, and material properties were analyzed. The finite element analysis (FEA) results were then fit to a series of equations. Both the original and modified ln-sec equations use Charpy impact energy to characterize the toughness of the pipeline steel. Failure models for crack-like flaws that are based on FEA are superior to the In-sec method, which was traditionally used in the pipeline industry. A new PRCI method based on a curve fit of FEA results provides a simpler alternative to performing custom FEA for each situation that one encounters. Source

Soltis J.,Quest Integrity Group | Lichti K.A.,Quest Integrity Group
Corrosion Science

Galvanic corrosion of carbon steel coupled to antimony was studied in aerated and N2-purged electrolytes at ambient and 60°C temperatures. Free corrosion potential of antimony and carbon steel shifts to more active values with increasing temperature and N2 purging of the electrolyte. Under all experimental conditions, antimony remains less electronegative than carbon steels. Aeration and temperature affect potentiodynamic behaviour of both materials. As a consequence, the corrosion current for the antimony-carbon steel couple increases with increasing temperature and with aeration. There was a good agreement between the corrosion currents obtained through the Evans' experiment and super-imposed potentiodynamic scans. © 2012 Elsevier Ltd. Source

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