Analysis of Threaded Connection Reliability for Compression Applications
Notice bibliographique
Résumé
Abstract The objective of this paper is the investigation and evaluation of the performance and life expectancy of NPT threaded connections as applied to a particular type of reciprocating compressor units. The study focused on the assessment of the levels of excitation forces acting on the threaded connections and the resulting stress. These forces and stresses were determined from field vibration measurements results applied to a mechanical model of the system. As an extensive literature search did not yield satisfactory data for specific fatigue properties of NPT connections, we applied a first-principles approach to the problem and calculated the stress concentration factors from a detailed Finite Element Study of the thread engagement under axial and circumferential loads. The results and details are reported here. Stress levels determined by this methodology were compared to the allowable fatigue limits for the piping and valves materials and a life expectancy was calculated. The same methodology can be applied to other situations involving threaded connections. Introduction In the process of evaluation for procurement, end users often have to make a decision between buying equipment that meets the operating conditions for the project but does not exactly conform to some of the user's own specifications or equipment with unacceptably long delivery times or that is even unavailable. Here it is shown a case study that exemplifies how decision makers can evaluate the reliability of equipment and therefore minimize risks while making a decision favoring the first option. Several given conditions of operation were considered in this study. The stress levels occurring on the threaded joints is strongly governed by the 'stress concentration factors' characteristic of the thread profile. An extensive literature search did not yield satisfactory data, either theoretical or empirical for specific fatigue properties of NPT connections or for the stress concentration at the threads. A first-principles approach to the problem was selected and evaluation of the stress concentration factors from a detailed Finite Element Study of the thread engagement under axial and circumferential loads was undertaken. The forces acting on the piping system were determined from several field vibration measurements results and were applied to the theoretical mechanical model of the system. The resulting stresses calculated from the Finite Element Model were then compared to the allowable fatigue limits for the piping and valves materials and a life expectancy was calculated. Several different methods were used to this effect. The Concern The package consists of a small natural gas compressor, scrubber, cooler and connecting pipe. The compressor utilizes one bank of cylinders of a 460 in3 Ford V8 engine retrofitted with pistons to compress gas while the other cylinder bank is used to provide power to the unit. The system assembly uses many NPT threaded fittings to join fuel gas lines, valves, process gas pipes and vessels. BP Canada Energy Co. requested AP Dynamics Inc. to investigate and evaluate the performance and life expectancy of the threaded connections on these modularized compressor packages.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».