Failure Analysis of Wire Ropes Used in Multi-Wire Machines for Cutting Blocks of Stone

ABSTRACT: This paper reports the analyses carried out with the company Pedrini SpA ad unico socio, located in Carobbio degli Angeli, Bergamo (IT). Wire ropes with diamond beads, used as cutting tools in multi-wire machines for cutting blocks of stone, were considered and a failure analysis of the wire ropes was carried out. The aim of the paper is to highlight the damage mechanisms of the wire ropes to increase service life of these cutting tools. Microscope observations and the penetrating liquids method were used to analyze the damaged wire ropes. Fatigue, corrosion and contact fatigue problems were observed and the effect of the centering of the beads on the wire rope was studied.

High-Temperature Tensile and Creep Behavior in a CrMoV Steel and Weld Metal

The 2.25Cr1Mo0.25V steel is a vanadium-modified 2.25Cr1Mo steel and is being widely used in the manufacture of heavy-wall hydrogenation reactors in petrochemical plants. However, the harsh service environment requires a thorough understanding of high-temperature tensile and creep behaviors of 2.25Cr1Mo0.25V steel and its weld for ensuring the safety and reliability of hydrogenation reactors. In this work, the high-temperature tensile and creep behaviors of base metal (BM) and weld metal (WM) in a 2.25Cr1Mo0.25V steel weldment used for a hydrogenation reactor were studied experimentally, paying special attention to its service temperature range of 350–500 °C. The uniaxial tensile tests under different temperatures show that the WM has higher strength and lower ductility than those of BM, due to the finer grain size in the WM. At the same time, the short-term creep tests at 550 °C reveal that the WM has a higher creep resistance than that of BM. Moreover, the creep damage mechanisms were clarified by observing the fracture surface and microstructures of crept specimens with the aid of scanning electron microscopy (SEM). The results showed that the creep damage mechanisms of both BM and WM are the initiation and growth of creep cavities at the second phase particles. Results from this work indicate that the mismatch in the high-temperature tensile strength, ductility, and creep deformation rate in 2.25Cr1Mo0.25V steel weldment needs to be considered for the design and integrity assessment of hydrogenation reactors.

The Virtual Corrosion Engineer

The conventional corrosion management process consists of defining the expected process conditions, identifying potential corrosion threats, and estimating their likely rate, then using that information to develop mitigation plans and inspection schedules. The Virtual Corrosion Engineer (VCE) project aims to improve this process by utilizing online monitoring data to automate the running of the best available corrosion models and provide a continuously updated dashboard in real time. This paper provides an overview of the VCE, together with a brief discussion of the underlying models for two exemplar damage mechanisms, High-Temperature Hydrogen Attack (HTHA) and Under Deposit Corrosion (UDC) in steam generators.

FORMATION DAMAGE MECHANISMS AND NUMERICAL SIMULATION OF PERMEABILITY IMPAIRMENT IN HORIZONTAL WELLS

Puzzling circumstance associated with formation damage near wellbore occur frequently, resulting in permeability impairments and increased pressure losses. Potential damage phenomenon usually starts from drilling to completion via production and such mechanisms have been fully considered. Most of the existing tasks to mitigate the near oil wellbore damages involve use of empirical models, conducting experiments, frequent shut down of wells for proper well tests and pressure maintenance are highly expensive and time consuming. Permeability impairments have been simulated by modifying Darcy’s equation to optimize reservoir pressure for improved near wellbore in horizontal wells. The model, transient linear partial differential equation (TLPDE) for impaired permeability is developed and numerically resolved using finite difference method. The model was implemented by writing codes in MATLAB language and the solution obtained was validated using synthetic/ field data. The results obtained for TLPDE model indicated pressure depletion over time. This was also shown for every values of coefficient of anisotropy until 400 days when the anisotropy became insignificant approaching isotropy condition, suggesting permeability impairment. Numerical simulation proved to be effective in simulating near oil wellbore damages. This paper describes the detailed mechanisms of formation damage and provided a numerical approach to model impaired permeability in horizontal wells. This approach allowed us to study the impact of various damage mechanisms related to drilling, completion conditions and significant improvement of near oil wellbore for well performance.