Establishing Fracture Mechanics Based Minimum Allowable Temperatures for Low Temperature Applications of ASME B31.3 Piping

2018 ◽  
Author(s):  
Seetha Ramudu Kummari ◽  
Brian Macejko ◽  
Kraig S. Shipley ◽  
Phillip E. Prueter ◽  
Geoff Evans ◽  
...  
Keyword(s):  
Low Temperature ◽  
Fracture Mechanics ◽  
Relaxation Effect ◽  
Allowable Stress ◽  
Section Viii ◽  
Level 1 ◽  
Major Crack ◽  
Stress Criteria ◽  
Level 2 ◽  
Temperature Applications

Impact test exemption curves in ASME B31.3 [1] were adopted from ASME Section VIII Division 1 (VIII-1) [2] with subtle modifications. The VIII-1 exemption curves were generated based on early fracture mechanics methodologies and limited amount of test data with an assumption on maximum applied stress intended to correspond to the typical VIII-1 allowable stress criteria. The applicability of the exemption curves for low temperature applications of ASME B31.3 piping (such as blowdown events) is open to discussion because of potentially high longitudinal thermal expansion stresses that may exceed the VIII-1 allowable stress criteria. Additionally, unlike in VIII-1 and ASME Section VIII Division 2 (VIII-2) [3], there is no post weld heat treatment (PWHT) credit on Minimum Design Metal Temperature (MDMT) in ASME B31.3. Detailed fracture mechanics analyses have shown that PWHT can significantly reduce the risk of brittle fracture failures due to its relaxation effect on weld residual stresses, a major crack driving force. In this paper, a fracture mechanics-based methodology for establishing Minimum Allowable Temperatures (MAT) for low temperature applications of ASME B31.3 piping is presented. A state-of-the-art fracture mechanics methodology published in Welding Research Council (WRC) Bulletin 562 [4] is used to develop step-by-step Level 1 and Level 2 procedures for establishing MAT for low temperature applications of ASME B31.3 piping. For the Level 1 methodology, MAT screening curves are developed based on a likely conservative assumption that the stresses in the piping component are at the maximum code allowable stresses in both the hoop and longitudinal directions. For the Level 2 methodology, stress ratio verses temperature reduction curves are developed to consider the effect of lower operating stresses. Similar to VIII-2 [3] toughness exemption curves, the screening curves are generated for both As-Welded and PWHT conditions. The curves can also be used for impact tested materials. The established MAT can be directly coupled to different reference flaw sizes and integrated with an inspection criteria for piping components. Two examples of establishing MAT using both the proposed Level 1 and Level 2 methodologies are presented herein.

Fitness-for-Service Assessment of Piping Subject to Random Vibration

2016 ◽  
Author(s):  
Lyle Breaux ◽  
Scot McNeill ◽  
Gyorgy Szasz
Keyword(s):  
Random Vibration ◽  
Cyclic Stress ◽  
Allowable Stress ◽  
Vibration Level ◽  
Vibration Loading ◽  
Design Life ◽  
The Subject ◽  
Level 1 ◽  
Target Design ◽  
Level 2

A methodology is presented for Level 1 and 2 Fitness-for-Service (FFS) assessments of process and power piping subject to random vibration loading. The intent is to provide a basis for random vibration assessment based on concepts from spectral fatigue, which is simplified to the degree that a non-specialist can conduct the FFS assessment with little prior knowledge of the subject matter. The proposed Level 1 FFS assessment is based on extension and generalization of established industry screening curves for piping vibration. The measured (overall) RMS vibration level is compared against allowable values given by the curves evaluated at the average crossing frequency of the measured vibration. The proposed Level 2 FFS assessment utilizes an allowable cyclic stress. The allowable stress is a function of the target design life as well as the average crossing frequency and kurtosis of the measured vibration. Both approaches are illustrated by example.

Proposed Modifications to API 579 Part 3 Brittle Fracture Screening Procedures

2019 ◽  
Author(s):  
Brian R. Macejko ◽  
Seetha Ramudu Kummari ◽  
Phillip E. Prueter
Keyword(s):  
Fracture Mechanics ◽  
Brittle Fracture ◽  
State Of The Art ◽  
Acceptance Criteria ◽  
Evaluation Procedures ◽  
Failure Assessment ◽  
Level 3 ◽  
Screening Procedures ◽  
Level 1 ◽  
Level 2

Abstract Significant inconsistencies and inadequacies exist in the current brittle fracture screening procedures in the 2016 edition of API 579-1/ASME FFS-1, Fitness-For-Service (API 579). Results from an evaluation completed using the current published guidance could prove unsafe in some instances. The ASME/API Joint Committee on Fitness-For-Service (FFS) recently initiated a project to rewrite API 579 Part 3, Assessment of Existing Equipment for Brittle Fracture. The intent of the project is to establish new Level 1 and Level 2 evaluation procedures and acceptance criteria developed using state-of-the-art fracture mechanics consistent with the Part 9 Failure Assessment Diagram (FAD) approach, currently employed in Level 3 FFS evaluations. This paper will provide a comprehensive summary of deficiencies and concerns with current published methods for evaluating susceptibility of pressure equipment to potential brittle fracture failures. Additionally, the paper will provide an overview of the methodology employed in the recently proposed procedure modifications for Part 3 of API 579 to mitigate the current deficiencies.

ANALISIS KEMAMPUAN KOMUNIKASI MATEMATIS DALAM MENYELESAIKAN MASALAH STATISTIKA

2018 ◽  
Vol 5 (2) ◽  
pp. 7 ◽  
Author(s):  
Ahmad Aunur Rohman
Keyword(s):  
Level 1 ◽  
Level 2

Penelitian ini dimaksudkan untuk mengetahui bagaimana kemampuan komunikasi matematis mahasiswa terhadap pemahaman statistika. Data dalam penelitian ini berupa hasil pekerjaan tes tertulis tentang kemampuan komunikasi matematis dan wawancara terhadap subjek penelitian. Pengumpulan data diperoleh dengan tes dan wawancara. Uji keabsahan data yang digunakan adalah triangulasi. Data penelitan yang terkumpul dianalisis dengan analisis data non statistik yang terdiri dari tiga alur, yaitu reduksi data, penyajian data, dan penarikan kesimpulan/verifikasi data. Hasil penelitian menunjukkan bahwa 1) Terdapat 5 mahasiswa yang berada pada level 0 (sangat kurang baik); 2) 24 mahasiswa berada pada level 1 (kurang baik); 3) 6 mahasiswa berada pada level 2 (cukup baik); Penelitian ini diharapkan dapat memacu individu lain untuk melakukan penelitian yang lebih baik dan mendalam tentang kemampuan komunikasi matematis.

EVALUASI PELATIHAN DI PT. PUPUK KUJANG CIKAMPEK

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Lania Muharsih ◽  
Ratih Saraswati
Keyword(s):  
Training Evaluation ◽  
Work Productivity ◽  
Learning Behavior ◽  
Level 3 ◽  
Level 1 ◽  
Four Levels ◽  
A Company ◽  
Level 2 ◽  
Evaluation Sheet ◽  
Assessment Factor

This study aims to determine the training evaluation at PT. Kujang Fertilizer. PT. Pupuk Kujang is a company engaged in the field of petrochemicals. Evaluation sheet of PT. Fertilizer Kujang is made based on Kirkpatrick's theory which consists of four levels of evaluation, namely reaction, learning, behavior, and results. At level 1, namely reaction, in the evaluation sheet is in accordance with the theory of Kirkpatrick, at level 2 that is learning should be held pretest and posttest but only made scale. At level 3, behavior, according to theory, but on assessment factor number 3, quantity and work productivity should not need to be included because they are included in level 4. At level 4, that is the result, here is still lacking to get a picture of the results of the training that has been carried out because only based on answers from superiors without evidence of any documents.   Keywords: Training Evaluation, Kirkpatrick Theory.    Penelitian ini bertujuan mengetahui evaluasi training di PT. Pupuk Kujang. PT. Pupuk Kujang merupakan perusahaan yang bergerak di bidang petrokimia. Lembar evaluasi PT. Pupuk Kujang dibuat berdasarkan teori Kirkpatrick yang terdiri dari empat level evaluasi, yaitu reaksi, learning, behavior, dan hasil. Pada level 1 yaitu reaksi, di lembar evaluasi tersebut sudah sesuai dengan teori dari Kirkpatrick, pada level 2 yaitu learning seharusnya diadakan pretest dan posttest namun hanya dibuatkan skala. Pada level 3 yaitu behavior, sudah sesuai teori namun pada faktor penilaian nomor 3 kuantitas dan produktivitas kerja semestinya tidak perlu dimasukkan karena sudah termasuk ke dalam level 4. Pada level 4 yaitu hasil, disini masih sangat kurang untuk mendapatkan gambaran hasil dari pelatihan yang sudah dilaksanakan karena hanya berdasarkan dari jawaban atasan tanpa bukti dokumen apapun.   Kata kunci: Evaluasi Pelatihan, Teori Kirkpatrick.

scholarly journals Conventional and Electromagnetic-induction Sintering of High Entropy Alloys for Low-temperature Applications

2020 ◽  
Vol 26 (S2) ◽  
pp. 2916-2917
Author(s):  
Luis Laguna Zubia ◽  
C.G. Garay-Reyes ◽  
M.A. Ruiz-Esparza-Rodriguez ◽  
J.M. Mendoza-Duarte ◽  
Ivanovich Estrada ◽  
...  
Keyword(s):  
Low Temperature ◽  
Electromagnetic Induction ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Temperature Applications

scholarly journals Celebrate Diversity?

2021 ◽  
Author(s):  
Christian Huber ◽  
Philipp Nicolay ◽  
Simone Weber
Keyword(s):  
Eine Hohe ◽  
Soziale Integration ◽  
Level 1 ◽  
Soziale Ausgrenzung ◽  
Level 2

ZusammenfassungSchulleistungen und soziale Integration sind im deutschen Schulsystem eng miteinander verbunden. Unklar ist, welche Rolle die Leistungs- und Verhaltensheterogenität für diesen Zusammenhang spielt. Vertreter*innen eines klassischen sozialpsychologischen Zugangs sagen für eine hohe Leistungs- und Verhaltensheterogenität eine Erhöhung des Risikos auf soziale Ausgrenzung (Risikohypothese) voraus, Vertreter*innen eines inklusionspädagogischen Zugangs eine Schutzfunktion (Schutzhypothese). Die vorliegende Studie untersucht, inwieweit die Leistungs- und Verhaltensheterogenität den Zusammenhang zwischen einem Förderbedarf in den Bereichen Lernen/Verhalten und sozialer Integration moderiert und ob die Richtung dieses Modertoreffekt im Sinne der Schutz- oder der Risikohypothese gedeutet werden kann. Hierzu wurden N = 1352 Grundschüler*innen in drei unterschiedlich heterogenen Schulsystemen (jahrgangsgetrennt, 1/2/3/4; teilweise jahrgangsübergreifend, 1–2/3–4; jahrgangsübergreifend, 1–4) in einer Querschnittstudie untersucht. Erhoben wurden, neben der sozialen Integration, Informationen über einen besonderen Förderbedarf in den Bereichen Lernen und Verhalten und Schulleistung. Das Schulsystem ging als unabhängige Variable auf Level 2, der Förderbedarf als unabhängige Variable auf Level 1 und die soziale Integration als abhängige Variable in die mehrebenenanalytische Auswertung ein. Analog zu bisher vorliegenden Befunden wurde ein signifikanter Haupteffekt beider Förderbedarfe auf die soziale Integration gefunden. Ferner zeigten vier von sechs Cross-Level-Effekten für den Förderbedarf Lernen Hinweise auf eine Gültigkeit der Schutzhypothese, kein Cross-Level-Effekt war im Sinne der Risikohypothese interpretierbar. Dieser Befund war nicht auf den Förderbedarf Verhalten übertragbar. Die Ergebnisse legen nahe, dass sich der Zusammenhang zwischen sozialer Integration und Förderbedarf Lernen mit zunehmender Leistungs- und Verhaltensheterogenität abschwächt. Gleichzeitig zeigte sich in den stark heterogenen Lerngruppen ein insgesamt erhöhtes Ausgrenzungsrisiko aller Schüler*innen unabhängig ihres Förderbedarfs. Die Ergebnisse lassen den Schluss zu, dass sich für Schüler*innen mit erhöhtem Förderbedarf Lernen im jahrgangsübergreifenden Lernen eine höhere Chance für eine gute soziale Integration einstellen könnte.

scholarly journals An Atmospheric Visibility Grading Method Based on Ensemble Learning and Stochastic Weight Average

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 869
Author(s):  
Xiuguo Zou ◽  
Jiahong Wu ◽  
Zhibin Cao ◽  
Yan Qian ◽  
Shixiu Zhang ◽  
...  
Keyword(s):  
Ensemble Learning ◽  
Traffic Accidents ◽  
Feature Sets ◽  
Atmospheric Visibility ◽  
Average Accuracy ◽  
Level 3 ◽  
Visual Characteristics ◽  
Level 1 ◽  
Grading Model ◽  
Level 2

In order to adequately characterize the visual characteristics of atmospheric visibility and overcome the disadvantages of the traditional atmospheric visibility measurement method with significant dependence on preset reference objects, high cost, and complicated steps, this paper proposed an ensemble learning method for atmospheric visibility grading based on deep neural network and stochastic weight averaging. An experiment was conducted using the scene of an expressway, and three visibility levels were set, i.e., Level 1, Level 2, and Level 3. Firstly, the EfficientNet was transferred to extract the abstract features of the images. Then, training and grading were performed on the feature sets through the SoftMax regression model. Subsequently, the feature sets were ensembled using the method of stochastic weight averaging to obtain the atmospheric visibility grading model. The obtained datasets were input into the grading model and tested. The grading model classified the results into three categories, with the grading accuracy being 95.00%, 89.45%, and 90.91%, respectively, and the average accuracy of 91.79%. The results obtained by the proposed method were compared with those obtained by the existing methods, and the proposed method showed better performance than those of other methods. This method can be used to classify the atmospheric visibility of traffic and reduce the incidence of traffic accidents caused by atmospheric visibility.

scholarly journals Identifying trauma patients with benefit from direct transportation to Level-1 trauma centers

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Charlie A. Sewalt ◽  
Benjamin Y. Gravesteijn ◽  
Daan Nieboer ◽  
Ewout W. Steyerberg ◽  
Dennis Den Hartog ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Trauma Center ◽  
Trauma Patients ◽  
Trauma Centers ◽  
Absolute Benefit ◽  
Predicted Probability ◽  
Prehospital Triage ◽  
Level 1 ◽  
Level 1 Trauma Center ◽  
Level 2

Abstract Background Prehospital triage protocols typically try to select patients with Injury Severity Score (ISS) above 15 for direct transportation to a Level-1 trauma center. However, ISS does not necessarily discriminate between patients who benefit from immediate care at Level-1 trauma centers. The aim of this study was to assess which patients benefit from direct transportation to Level-1 trauma centers. Methods We used the American National Trauma Data Bank (NTDB), a retrospective observational cohort. All adult patients (ISS > 3) between 2015 and 2016 were included. Patients who were self-presenting or had isolated limb injury were excluded. We used logistic regression to assess the association of direct transportation to Level-1 trauma centers with in-hospital mortality adjusted for clinically relevant confounders. We used this model to define benefit as predicted probability of mortality associated with transportation to a non-Level-1 trauma center minus predicted probability associated with transportation to a Level-1 trauma center. We used a threshold of 1% as absolute benefit. Potential interaction terms with transportation to Level-1 trauma centers were included in a penalized logistic regression model to study which patients benefit. Results We included 388,845 trauma patients from 232 Level-1 centers and 429 Level-2/3 centers. A small beneficial effect was found for direct transportation to Level-1 trauma centers (adjusted Odds Ratio: 0.96, 95% Confidence Interval: 0.92–0.99) which disappeared when comparing Level-1 and 2 versus Level-3 trauma centers. In the risk approach, predicted benefit ranged between 0 and 1%. When allowing for interactions, 7% of the patients (n = 27,753) had more than 1% absolute benefit from direct transportation to Level-1 trauma centers. These patients had higher AIS Head and Thorax scores, lower GCS and lower SBP. A quarter of the patients with ISS > 15 were predicted to benefit from transportation to Level-1 centers (n = 26,522, 22%). Conclusions Benefit of transportation to a Level-1 trauma centers is quite heterogeneous across patients and the difference between Level-1 and Level-2 trauma centers is small. In particular, patients with head injury and signs of shock may benefit from care in a Level-1 trauma center. Future prehospital triage models should incorporate more complete risk profiles.

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