Root Cause Analysis of Dent With Crack: A Case Study

2012 ◽  
Author(s):  
Udayasankar Arumugam ◽  
Ming Gao ◽  
Ravi Krishnamurthy ◽  
Rick Wang ◽  
Richard Kania
Keyword(s):  
Failure Modes ◽  
Fatigue Testing ◽  
Strain Analysis ◽  
Ductile Failure ◽  
Field Investigation ◽  
Primary Objective ◽  
Metal Loss ◽  
Pipe Surface ◽  
Strain Limit

A combined caliper and tri-axial MFL in-line inspection (ILI) reported a bottom side 2.7%OD dent associated with 76% metal loss. The reported dent depth is well below the 6% limit while strain analysis of this ILI dent profile showed a maximum equivalent strain of 17.4%, which exceeds the 6% strain limit for gas pipeline. Due to the high dent strain level, the raw signals of metal loss were revisited, which indicated this associated metal loss appears to be a crack rather than corrosion. In-field investigation revealed that this dent is indeed associated with branched cracks both at internal and external pipe surface but no leak was detected. The primary objective of this case study is to determine the cause for cracking in the dent. As part of this study, detailed investigation was performed including LaserScan based strain analysis, lab pressure-cycle testing and fracture surface examination. An attempt was made to quantify the plastic strain damage of this dent and its susceptibility to cracking using the existing plastic damage models, namely, ductile failure damage indicator (DFDI), strain limit damage (SLD) and minimum elongation limit criterion. The investigation showed that the internal cracks were formed at the time of indentation while the external cracks formed by spring-back (elastic rebounding) due to the removal of rock constraint. Full size fatigue testing of this cracked dent showed leak failure modes rather than rupture. In this paper, the approach, results and the findings are summarized and discussed.

Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks ◽  
Zhiyong Pei ◽  
Ling Zhu
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Large Scale ◽  
Failure Modes ◽  
Bending Strength ◽  
Metal Loss ◽  
Pipe Surface ◽  
Comparison Results ◽  
Mechanical Interference ◽  
Bending Capacity

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage after mechanical interference. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe tests. Artificial damage, such as a dent, metal loss, a crack, and combinations thereof, is introduced to the pipe surface in advance. Four-point bending tests are performed to investigate the structural behavior of metallic pipes in terms of bending moment–curvature diagrams, failure modes, bending capacity, and critical bending curvatures. Test results show that the occurrence of structural damage on the pipe compression side reduces the bending capacity significantly. Only a slight effect has been observed for pipes with damage on the tensile side as long as no fracture failure appears. The possible causes that have introduced experimental errors are presented and discussed. The test data obtained in this paper can be used to further quantify damage effects on bending capacity of seamless pipes with similar D/t ratios. The comparison results in this paper can facilitate the structural integrity design as well as the maintenance of damaged pipes when mechanical interference happens during the service life of pipelines.

The Bending Fatigue Response of Fatigue Strength of PVC Pipe and Pipe Joints

2006 ◽  
Author(s):  
R. J. Scavuzzo ◽  
T. S. Srivatsan
Keyword(s):  
Fatigue Strength ◽  
Internal Pressure ◽  
Research Council ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Phase 1 ◽  
Pipe Surface ◽  
Bending Fatigue ◽  
Pvc Pipe

In a two-year program, seventy-eight specimens of PVC pipe with and without adhesive socket joints were tested in a four-point bending apparatus. Internal pressures were varied from atmospheric pressure (0 psig) to the rated internal pressure of 280 psig. Results of the plain pipe are compared to pipe with joints. All testing was done using a special apparatus developed to accommodate the large deformations required for fatigue testing of PVC pipes. This apparatus is described as well as the test results. Both strains and stresses are plotted against cycles-to-failure. Finite element elastic models of the socket joined specimens were analyzed to establish the areas of stress concentration and to explain the observed failure modes. Phase 1 testing indicated that the pipe internal pressure might have a significant effect on fatigue life. Joined pipe specimens with no internal pressure were weaker in bending fatigue than pressurized pipe. As a result, the internal pressure was systematically varied between 0 psig and the rated pressure 280 psig. Results of Phase 2 testing revealed a dependence on internal pressure. Also, the effects of an adhesive primer and roughening of the pipe surface on joint fatigue strength were also studied. Strain rate is known to exert a profound influence on the fatigue behavior of thermoplastic polymers. This effect has not been systematically studied and remains an unknown. This research was supported by two grants from the Pressure Vessel Research Council. Additional details of the research are compiled in the Welding Research Council (WRC) Bulletin 445.

A Combined Approach to Characterization of Dent With Metal Loss

2012 ◽  
Author(s):  
Rick Yahua Wang ◽  
Richard Kania ◽  
Udayasankar Arumugam ◽  
Ming Gao
Keyword(s):  
Mechanical Damage ◽  
Practical Experience ◽  
Metal Loss ◽  
Combined Approach ◽  
Detailed Characterization ◽  
Strain Limit ◽  
Study Results ◽  
Damage Criteria

Current in-line inspection technologies (e.g., Caliper/MFL or Combo) for mechanical damage characterization can detect dent with metal loss but with limited ability to discriminate metal loss between corrosion, gouge and crack with certainty. There are also some cases that metal loss signals were detected but not reported by ILI vendors because of either signals below threshold for reporting or other reasons. Practical experience showed that, with assistance of strain based dent analysis and strain limit damage criteria; detailed characterization of MFL tri-axial signals could effectively facilitate to discriminate metal loss features and identify potential risk of cracks or gouges in the dent. In this paper, the newly developed approach is utilized to identify the critical dents in the pipelines and discriminate those dents associated with metal loss reported by combined ILI technologies. A case study was performed with four real dent features, as an example to demonstrate the effectiveness of this approach. The details of the case study, results and findings are summarized in this paper.

Failure Analysis Case Study of a 1.5 Meter Space Flex Harness

2017 ◽  
Author(s):  
Erick Kim ◽  
Kamjou Mansour ◽  
Gil Garteiz ◽  
Javeck Verdugo ◽  
Ryan Ross ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Failure Modes ◽  
Field Of View ◽  
Area Of Interest ◽  
Air Stream ◽  
Novel Method ◽  
Temperature Controlled ◽  
Non Destructive ◽  
Failure Site

Abstract This paper presents the failure analysis on a 1.5m flex harness for a space flight instrument that exhibited two failure modes: global isolation resistances between all adjacent traces measured tens of milliohm and lower resistance on the order of 1 kiloohm was observed on several pins. It shows a novel method using a temperature controlled air stream while monitoring isolation resistance to identify a general area of interest of a low isolation resistance failure. The paper explains how isolation resistance measurements were taken and details the steps taken in both destructive and non-destructive analyses. In theory, infrared hotspot could have been completed along the length of the flex harness to locate the failure site. However, with a field of view of approximately 5 x 5 cm, this technique would have been time prohibitive.

Case Study and Fault Modeling for Wrong Redundancy Evaluation on DRAM Devices

2007 ◽  
Author(s):  
Martin Versen ◽  
Dorina Diaconescu ◽  
Jerome Touzel
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Fault Modeling ◽  
Mode Analysis ◽  
Root Cause ◽  
Failure Mode Analysis

Abstract The characterization of failure modes of DRAM is often straight forward if array related hard failures with specific addresses for localization are concerned. The paper presents a case study of a bitline oriented failure mode connected to a redundancy evaluation in the DRAM periphery. The failure mode analysis and fault modeling focus both on the root-cause and on the test aspects of the problem.

Methodology for Analysis of Schottky Diode Failures

2010 ◽  
Author(s):  
Bhanu P. Sood ◽  
Michael Pecht ◽  
John Miker ◽  
Tom Wanek
Keyword(s):  
Failure Mode ◽  
Schottky Diode ◽  
Failure Modes ◽  
Schottky Diodes ◽  
Failure Mechanisms ◽  
Forward Voltage ◽  
Fast Switching ◽  
Voltage Drops ◽  
The Common

Abstract Schottky diodes are semiconductor switching devices with low forward voltage drops and very fast switching speeds. This paper provides an overview of the common failure modes in Schottky diodes and corresponding failure mechanisms associated with each failure mode. Results of material level evaluation on diodes and packages as well as manufacturing and assembly processes are analyzed to identify a set of possible failure sites with associated failure modes, mechanisms, and causes. A case study is then presented to illustrate the application of a systematic FMMEA methodology to the analysis of a specific failure in a Schottky diode package.

Design of water allocation model: efficiency and risk aspects

2005 ◽  
Vol 5 (3-4) ◽  
pp. 9-16
Author(s):  
C. Kim ◽  
D. Han
Keyword(s):  
Water Allocation ◽  
Primary Objective ◽  
Allocation Model ◽  
Proportional Allocation ◽  
Model Efficiency ◽  
Service Sectors ◽  
Expected Benefits ◽  
Water Allocation Model ◽  
Allocation Methods

The primary objective of this study is to improve the methodology for water allocation focused on efficiency and risk aspects. To attain the primary objective, this study sets up an objective function to maximize social expected benefits, and considers three types of allocation methods. Three types of allocation methods are optimal, proportional, and fixed allocation between regions and service sectors. The results of case study area shows that the fixed allocation method is preferred to the proportional allocation in most cases except that the variance of flow is small with respect to efficiency. Also, efficient and less-risky allocation is simultaneously obtained in some cases, while efficiency and risk show the relation of trade-off in other cases.

scholarly journals A FMEA Based Method for Analyzing and Prioritizing Performance Risk at the Conceptual Stage of Performance PSS Design

2021 ◽  
Vol 1 ◽  
pp. 81-90
Author(s):  
John Bake Sakwe ◽  
Marcus Pereira Pessoa ◽  
Sipke Hoekstra
Keyword(s):  
Failure Modes ◽  
Manufacturing Companies ◽  
Performance Risk ◽  
Performance Contracts ◽  
Product Service ◽  
Optical Sorting ◽  
Fmea Method ◽  
Performance Challenges ◽  
Product Service Systems

AbstractWith the quest for enhancing competitive position, fulfilling customer and sustainability demands, increasing profitability, asset manufacturing companies are now adapting assets towards product service systems (PSS) offered through performance contracts. Despite several benefits, the shift to performance PSS exposes industrial asset manufacturers' to performance challenges and risks. Currently, PSS designers face a challenge to exhaustively identify potential failures during PSS development. Knowledge of Product failures is critical prior to the engineering of PSS. This paper proposes a failure modes and effects analysis (FMEA) method to support designers' prioritise critical failures in performance PSS development. A case study of an optical sorting machine is used to demonstrate the method's application.

Failure mode and effect analysis (FMEA) to improve collaborative project-based learning: Case study of a Study and Research Path in mechanical engineering

2021 ◽  
pp. 030641902199904
Author(s):  
Elena Bartolomé ◽  
Paula Benítez
Keyword(s):  
Active Learning ◽  
Failure Mode ◽  
Mechanical Engineering ◽  
Failure Modes ◽  
Collaborative Study ◽  
Project Based Learning ◽  
Educational Process ◽  
Effect Analysis ◽  
Questions And Answers

Failure Mode and Effect Analysis (FMEA) is a powerful quality tool, widely used in industry, for the identification of failure modes, their effects and causes. In this work, we investigated the utility of FMEA in the education field to improve active learning processes. In our case study, the FMEA principles were adapted to assess the risk of failures in a Mechanical Engineering course on “Theory of Machines and Mechanisms” conducted through a project-based, collaborative “Study and Research Path (SRP)” methodology. The SRP is an active learning instruction format which is initiated by a generating question that leads to a sequence of derived questions and answers, and combines moments of study and inquiry. By applying the FMEA, the teaching team was able to identify the most critical failures of the process, and implement corrective actions to improve the SRP in the subsequent year. Thus, our work shows that FMEA represents a simple tool of risk assesment which can serve to identify criticality in educational process, and improve the quality of active learning.

scholarly journals A Case Study in View of Developing Predictive Models for Water Supply System Management

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3305
Author(s):  
Katarzyna Pietrucha-Urbanik ◽  
Barbara Tchórzewska-Cieślak ◽  
Mohamed Eid
Keyword(s):  
Water Supply ◽  
Predictive Models ◽  
Failure Modes ◽  
Supply System ◽  
Water Supply System ◽  
System Management ◽  
System A ◽  
Operational Failure ◽  
Operational Data

Initiated by a case study to assess the effectiveness of the modernisation actions undertaken in a water supply system, some R&D activities were conducted to construct a global predictive model, based on the available operational failure and recovery data. The available operational data, regarding the water supply system, are the pipes’ diameter, failure modes, materials, functional conditions, seasonality, and the number of failures and time-to-recover intervals. The operational data are provided by the water company responsible of the supply system. A predictive global model is proposed based on the output of the operational data statistical assessment. It should assess the expected effectiveness of decisions taken in support of the modernisation and the extension plan.

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