Helmuth Sarmiento Klapper
Baker Hughes
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Featured researches published by Helmuth Sarmiento Klapper.
Corrosion | 2013
Helmuth Sarmiento Klapper; John H. Stevens; Gabriela Wiese
Austenitic stainless steels have been used for many years in components for drilling equipment. These stainless steels are predestinated to meet the demanding requirements in terms of mechanical, m...
Philosophical Transactions of the Royal Society A | 2017
Helmuth Sarmiento Klapper; Jutta Klöwer; Olesya Gosheva
Precipitation hardenable (PH) nickel (Ni) alloys are often the most reliable engineering materials for demanding oilfield upstream and subsea applications especially in deep sour wells. Despite their superior corrosion resistance and mechanical properties over a broad range of temperatures, the applicability of PH Ni alloys has been questioned due to their susceptibility to hydrogen embrittlement (HE), as confirmed in documented failures of components in upstream applications. While extensive work has been done in recent years to develop testing methodologies for benchmarking PH Ni alloys in terms of their HE susceptibility, limited scientific research has been conducted to achieve improved foundational knowledge about the role of microstructural particularities in these alloys on their mechanical behaviour in environments promoting hydrogen uptake. Precipitates such as the γ′, γ′′ and δ-phase are well known for defining the mechanical and chemical properties of these alloys. To elucidate the effect of precipitates in the microstructure of the oil-patch PH Ni alloy 718 on its HE susceptibility, slow strain rate tests under continuous hydrogen charging were conducted on material after several different age-hardening treatments. By correlating the obtained results with those from the microstructural and fractographic characterization, it was concluded that HE susceptibility of oil-patch alloy 718 is strongly influenced by the amount and size of precipitates such as the γ′ and γ′′ as well as the δ-phase rather than by the strength level only. In addition, several HE mechanisms including hydrogen-enhanced decohesion and hydrogen-enhanced local plasticity were observed taking place on oil-patch alloy 718, depending upon the characteristics of these phases when present in the microstructure. This article is part of the themed issue ‘The challenges of hydrogen and metals’.
Corrosion | 2014
Helmuth Sarmiento Klapper; John H. Stevens
As a result of their appropriate mechanical and non-magnetic properties, Alloy 718 (UNS N07718) has been used in directional drilling tools, particularly in applications where superior corrosion re...
Corrosion | 2017
Helmuth Sarmiento Klapper; Raul B. Rebak
Nickel alloys are broadly used in upstream oil and gas applications as a result of an advantageous set of properties including high mechanical strength accompanied by good ductility and toughness, ...
Acta Metallurgica Sinica (english Letters) | 2017
Helmuth Sarmiento Klapper; Natalia S. Zadorozne; Raul B. Rebak
There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase. Nickel alloys are generally designed for and used in highly aggressive environments, for example, those where stainless steels may experience pitting corrosion or environmentally assisted cracking. While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments, they may be prone to crevice corrosion attack. Addition of chromium, molybdenum and tungsten increases the localized corrosion resistance of nickel alloys. This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations, in the chemical process industry and in seawater service.
Corrosion | 2013
Helmuth Sarmiento Klapper; John H. Stevens
Archive | 2015
Anne Bartetzko; Joerg Lehr; Helmuth Sarmiento Klapper; Marcus Davidson; Elke Bozau
Corrosion | 2016
Helmuth Sarmiento Klapper; Matthias R. Moeller; Mark Paquette
Corrosion | 2017
Jutta Klöwer; Zahra Tarzimoghadam; Helmuth Sarmiento Klapper; Olesya Gosheva; Oriana Tassa
Corrosion | 2017
Helmuth Sarmiento Klapper; Joerg Lehr; Anne Bartetzko