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Role of Metallographic Characterization in Failure Analysis – Case Studies

Product Number: MPWT19-14379

Author: Syed Ahsan Ali

Publication Date: 2019

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Conducting a materials failure analysis requires a carefully planned series of steps intended to
arrive at the cause of the problem. Consistent with the current trend towards better accountability
and responsibility, failure analysis purpose has been extended in deciding which party may be
liable for losses, be they loss of production, property damage, injury, or fatality [1]. Hence it
increases the importance of proper implementation of characterization tools in failure analysis to
rightly identify the failure mode.
Present work discusses a few case studies to shed light upon the importance of the metallurgical
characterization tools and techniques in identification of correct failure mode. Some typical case
studies where metallography plays a very important role have been discussed, such as improper
welding joints which led to premature failure, sensitization and stress corrosion cracking in S.S.,
improper heat treatment and forging indicated the microstructures which led to the premature
failure. These cases are examples of only a few laboratory based investigations which justify that
without metallography it is not possible to diagnose the causes of premature failures.
Generally, examination of failed components commence with the low-power stereomicroscope
whereas hand-held magnifying lenses are still in wide use by experts to study fractures mostly
limited now for field purpose [2]. Metallographic examination typically is performed after nondestructive
and macroscopic examination procedures while using the light optical microscopy
which helps to assess the failure mode with respect to material defects, shortcomings in
processing, metallurgical changes etc. Since light optical microscopy has limited value for direct
observation of fracture surfaces (more limited for metals than non-metals), with still more factual
information can be gathered by scanning electron microscopy at higher magnification.

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Role of Non-Metallic Inclusions and the Microstructure Constituents on HIC Performance

Product Number: MPWT19-14439

Author: Amro Al-Hattab1,Diaa Elsanosy2, Gaurav Tomer3, Abdullah Al-Jarbou4

Publication Date: 2019

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With increasing oil & gas demand and depletion of sweet reserves, oil & gas companies in the regional
economies are focusing towards the exploitation of sour resources. This necessitates the use of pipelines
and down-hole tubing made from special steels with significant resistance to hydrogen-induced cracking
(HIC). These steels are produced through specific technologies for enhanced chemical composition control
and microstructural engineering to incorporate the required strength, weld ability and improved HIC
resistance. It is well established that the HIC initiates at sites with microstructural heterogeneities whether
due to presence of gross nonmetallic inclusions or the micro-structural constituents. The presence of central
segregation further aggravates the conditions particularly when the final pipe sizes require the longitudinal
slitting of the coils. Presence of non-metallic inclusions in the steel makes it vulnerable to hydrogen-induced
cracking under wet H2S environment. The mechanism of HIC begins with the generation of hydrogen atoms
by corrosion reaction of H2S and Fe in the presence of free water. The hydrogen atoms then diffuse into
steel and accumulate around the inclusions. The higher number of inclusions equates to the more sites
available for hydrogen adsorption. Recombination of hydrogen atoms to H2 molecules builds up a heavy
gas pressure in the interface between matrix and inclusions. Cracking initiates because of the tensile stress
field caused by hydrogen gas pressure and crack propagates in the surrounding steel matrix. The
longitudinal slitting exposes the internal microstructural abnormalities to the skelp edges which are then
incorporated in the thermally stressed weld zone. While the post-weld heat treatment (PWHT) mostly
homogenizes the weld zone microstructure, the presence of excessive central line features cannot be
completely removed thereby making this zone more prone to HIC attack

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Rotational Lining System and Use of High-Performance Thermoplastics

Product Number: MPWT19-15307

Author: Derek Lowth, Murali Adhyatmabhattar, Emma Mitchell

Publication Date: 2019

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Protecting carbon steel oil and gas pipelines with thermoplastic liners is a proven and cost-effective solution to prevent internal corrosion and abrasion. However, the industry is still facing considerable challenges when it comes to fittings and accessories such as elbows, tees, process equipment and complicated shapes.
Rotational lining (aka rotolining) is a technology which bonds a single/multi layered uniform, vacuum resistant, seamless polymer layer to the interior of virtually any metallic structure, regardless of shape and complexity. Once cooled, the result is a monolithic corrosion and chemical resistant lining that conforms to complex shapes and virtually free of stresses. This system results in a high quality and fully thermoplastic lined system.
Rotolining has been proven to provide long-term protection against corrosion and abrasion in various applications including saline water pipe systems, hydrocarbon service, mining and highly aggressive chemical service. This lining system can cover a wide range of fluid requirements, temperatures and applications using high-performance thermoplastics such as HDPE, PA-12, PVDF, ETFE and PFA. Rotolining is a cost-effective alternative to conventional solutions such as FBE, corrosion resistant alloy cladding or continuous chemical injection programs.
In this paper, some of the insights of the rotational lining system and usage of different high-performance thermoplastics are shared. This includes some very challenging and internationally proven case studies, which substantially benefited the entire value chain as long-term solutions

Product Number: 51321-16773-SG

Author: Xiang Zhou; Zhengrong Ye; Weidong Jiang; Xiaodong Cui; Donghong Guo; Guohao Chen; Huachang Chi; Feifei Huo; Zhiwen Yang; Yingfeng Chen; Lei Zhang

Publication Date: 2021

$20.00

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Scaling Risk Assessment and Remediation in Geothermal Operations Using a Novel Theoretical Approach

Product Number: 51324-20701-SG

Author: Gaurav Das; Jerzy Kosinski; Ronald D. Springer; Andre Anderko

Publication Date: 2024

$40.00

Geothermal power holds immense potential as a renewable energy source with low emissions utilizing the Earth's natural heat to generate electricity. With growing concerns over climate change and the need for sustainable energy alternatives, geothermal power can provide energy independence, economic benefits, and versatility. Mineral scaling has been recognized as a major hindrance in seamless geothermal operations due to the harsh and diverse operating conditions, which can cause significant issues resulting in higher operating costs while reducing energy production's efficiency and overall economic feasibility. Therefore, there is a growing need for a tool that can help in designing preventive and remedial strategies against mineral scaling and, in effect, ensure seamless operation while reducing costs associated with equipment failure. A few of the most commonly occurring scales in geothermal operations across different regions are amorphous silica (SiO2), metal silicates, and calcite (CaCO3). Formulating an effective theoretical framework to identify the critical conditions and characteristics of scaling solids is imperative in devising preventive and/or remedial measures. This multi-faceted problem requires the simultaneous modeling of solution thermodynamics and kinetics. In this work, we propose a novel modeling scheme through the incorporation of the classical nucleation theory (CNT) with the Mixed-Solvent Electrolyte (MSE) thermodynamic model. While MSE assesses scaling risk based on the effective evaluation of the solution chemistry, CNT provides kinetic information, i.e., an estimate of induction time, based on the continuum thermodynamics treatment of clusters. This work focuses on applying the novel theoretical approach in providing accurate thermodynamic modeling of the scales and subsequent applications of the kinetic modeling in deriving remedial techniques. The theoretical framework aims to provide a consistent approach for testing various what-if scenarios and aid in making the best operational solution in the development of flow assurance.

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SCC Behavior Of Alloy 52M Weld Butter On SA-508 LAS From The Double-Repair Dissimilar Metal Weld In A PWR Environment

Product Number: ED22-17283-SG

Author: Bogdan Alexandreanu, Yiren Chen

Publication Date: 2022

$20.00

This paper presents the results of a confirmatory research program conducted with the purpose of evaluating the susceptibility of Nickel-base Alloy 690 and 52/152 and variant welds to stress corrosion cracking (SCC) with a focus on the SCC response of Alloy 52/152 weldments with repairs.Nickel-base Alloy 690 and the associated weld Alloys 52 and 152 are typically used for nozzle penetrations in replacement heads for pressurized water reactor (PWR) vessels, repairs of existing components as well as for designs of advanced nuclear reactors because of their increased resistance to stress corrosion cracking (SCC) relative to Alloys 600, 82, and 182.

Online Conference Paper

Association for Materials Protection and Performance