The transportation of wet gas fluid in carbon steel pipelines for onshore processing offers an economically attractive strategy. Although a substantial saving in capital cost can be realised, the risks of hydrate formation and corrosion damage are two of the main issues with such an approach. The standard industrial practice is to apply chemical solutions to reduce the risks. A thermodynamic hydrate inhibitor, such as monoethylene glycol (MEG) and corrosion inhibitors are commonly utilized to provide hydrate and corrosion control, respectively. Other production chemicals, such as an oxygen scavenger, may also be deployed as part of the risk management process. Consequently, the main challenge to the corrosion inhibitor is to provide corrosion protection throughout the production and processing facility while subjected to high temperatures in the MEG regeneration process and exposure to other production chemicals. Thermal stability and performance assessments should be an important aspect of the qualification process in the selection of corrosion inhibitors. This paper presents data from laboratory corrosion inhibitor evaluation programs, using thermally stressed MEG/chemicals under simulated wet gas pipeline operating conditions, which resulted in the successful qualification of a corrosion inhibitor for the production facility. In addition, the performance of oxygen scavengers for use in MEG systems is reviewed, including details of an oxygen scavenger that performs in lean MEG.

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On September 21, 2015, the National Transportation Safety Board responded to a petroleum leak from a transmission pipeline in Centreville, VA. A small through crack was found leaking at a dent on the underside of the pipe, located away from any welds. The investigation found that corrosion fatigue could initiate at small dents, typically caused by impingement. While top-side dents from excavation and servicing have well-been documented and regulated, bottom-side dents, deemed acceptable per regulations, were found to be susceptible to stress corrosion and fatigue cracking. This investigation explored multiple and fundamental aspects of cracking in steel pipe dents, including nondestructive inspection, electron microscopy, finite element modeling, and long-term cyclic loading tests to characterize the cause of this pipeline accident.

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Metallic nanolayered composite materials can exhibit yield strengths one and a half to two times that of the constituents from which they are constructed. However, experimental data frequently show that there is a critical bi-layer period Λ below which the strength no longer increases with decreasing Λ To help understand the origins of this behavior and to guide future design of multilayers, maps of the internal stress and overall tensile macroyield stress are calculated as functions of the volume fractions of the two alternating constituents and bi-layer period, for a given lattice parameter ratio and elastic modulus ratio. Adopted here is a premise suggested by embedded atom simulations of Cu/Nb multilayers and recent experimental work on γ -Ni/γ-Ni3Al multilayers that the overall tensile strength is determined by the applied stress needed to eliminate the compressive bi-axial stress in the alternating layers. The results indicate that indeed, there is a critical bi-layer period below which the strength is independent of bi-layer period. In this regime, multilayer tensile strength is most effectively improved by increasing the stored compressive stress. This is achieved by decreasing the volume fraction of the compressively stressed phase. This manuscript extends previous work by providing closed-form expressions for the macroyield strength of free-standing multilayered thin films.