Piping stress analysis pdf

 
    Contents
  1. Design of Piping Systems
  2. Design of Piping Systems - PDF Free Download
  3. Piping Stress Analysis
  4. Pipe Stress Analysis

To get the full benefit from this tutorial, you will need a working copy of CAEPIPE, pipe stress analysis software. Download a Free Copy of CAEPIPE here. Why do Pipe Stress Analysis? • Pipe stress analysis is concerned with the prevention of overstressing pipes, skids, vessels, flanges, bolting, gaskets, valves . PDF | This paper presents engineering decision-making on pipe stress analysis through the application of knowledge-based systems (KBS). Stress analysis, as.

Author:MALKA NEIDECKER
Language:English, Spanish, Japanese
Country:Madagascar
Genre:Politics & Laws
Pages:200
Published (Last):22.11.2015
ISBN:767-7-67402-624-2
Distribution:Free* [*Registration needed]
Uploaded by: HUBERT

52335 downloads 120404 Views 39.49MB PDF Size Report


Piping Stress Analysis Pdf

rattribillvordo.ga - Free download as Powerpoint Presentation .ppt), PDF File .pdf), Text File .txt) or view presentation slides online. Piping Stress Analysis. 1. INTRODUCTION. Pipes are the most delicate components in any process plant. They are also the busiest entities. They are subjected. software make use of Finite Element Methods to carry out stress analysis in order to Piping Stress analysis is a term applied to calculations, which address the.

Piping subject to external pressures. Critical services. The key when performing a pipe stress analysis is determining the required level of detail. How to model the piping system Pipe stress analysis computer models are a series of 3-D beam elements that create a depiction of the piping geometry. Three-dimensional beam elements are the most efficient way to model the piping system, but not necessarily the most accurate; and without complex finite element models, it is nearly impossible to account for everything. However, it is known from historical empirical testing that these methods and 3-D beam computer models demonstrate enough behavior that they are a good approximation. That being said, there are some pitfalls with modeling piping systems that one should avoid: The computer models are only as good as the information entered into them. It is important when developing a pipe stress analysis, as with any finite element analysis FEA model, to also understand the physics and boundary conditions of the model. Elements used to model the piping system have their limitations. One-dimensional beam elements are great for straight pieces of piping, but not so good with pipe fittings elbows, tees, reducers, etc. They allow for greater approximation without using complex FEA models with shells, plates, and brick elements.

Markl, Piping Flexibility Analysis - A. Rodabaugh and H. Murphy, C. Soderberg, H.

You might also like: CUCKOO MALWARE ANALYSIS PDF

Blumberg, and D. Markl, E. This is an old book and some of the data is dated but any piping engineer will benefit from reading it cover to cover. The other book that has suddenly become available again veteran piping engineers will appreciate this is the olde NAVCO Datalog.

This little spiral bound gem includes all sorts of valuable piping data. Probably the most data in a small package. It is important to know where you can go to ask good questions. The sources of information cited above will serve you well for about 70 percent of the piping systems that you are called upon to design.

You will learn techniques for the analysis of buried systems, double containment piping systems, non-metallic piping systems plastic, glass, etc. Una cosa alla volta.

In mancanza di altre informazioni non vi sbagliate se lo considerate pari a 3mm. A seconda della normativa in uso questi parametri possono entrare o meno in determinate verifiche della linea.

Design of Piping Systems

Dunque prima di aprire il programma di calcolo e buttare dentro quei numeri a casaccio documentatevi su come la normativa ed il software gestiscono questi numeri. In mancanza di chiarezza conviene usare il metodo rozzo ma sempre affidabile di far girare il calcolo con o senza il parametro che si intende considerare e vedere come il programma reagisce al cambiamento. Esempio pratico Domanda Mettiamo che la normativa che sto usando non consideri lo spessore di corrosione in una determinata verifica.

Come faccio? Risposta Semplice.

Design of Piping Systems - PDF Free Download

Duplica il calcolo e sostituisci manualmente lo spessore nominale con quello corroso nelle parti interessate. Un altro caso di sostituzione manuale dello spessore fu necessario nel calcolo della linea del vapore principale di una centrale elettrica. Se ve lo state chiedendo - ebbene si, questo metodo non tiene conto del fatto che una parte del tubo possa essere sopraspessorato ed una parte sottospessorato.

Saldature Le tubazioni vengono connesse in due modi, attraverso saldature o connessioni flangiate. Le saldature sono potenzialmente elementi deboli della tubazione e dunque un fattore di efficienza andrebbe tenuto in considerazione. Figura 1. Le dimensioni della flangia sono abbastanza ininfluenti al punto che ci sono dei programmi di calcolo che la considerando addirittura un peso puntiforme.

Piping Stress Analysis

Altri programmi di calcolo permettono di includere dimensioni e peso della flangia insieme alla valvola a cui fossero connesse ma io sconsiglio di usare questa scorciatoia se non altro per motivi grafici. Il diametro interno del tubo e della flangia coincidono il che riduce i fenomeni di turbolenza ed erosione durante il passaggio. Onestamente le ho incontrate tante volte quante se ne potrebbero contare in una mano.

Un anello metallico viene compresso tra le facce delle flane e garantisce una migliore resistenza alla pressione. Le flange sono poi identificate dalla loro classe. Ogni classe ha la sua tabella di pressione massima in funzione della temperatura operativa. Ovviamente per una data temperatura occorre che la pressione massima della flangia sia superiore alla pressione effettivamente presente. Inizialmente le classi venivano chiamate pounds in quanto originariamente la classe equivaleva proprio alla pressione massima consentita.

In altri termini una flangia classe resisteva proprio a psi pounds per square inch, libbre per pollici quadrati alla temperatura di riferimento. No accounting for a large shear load. Wall deflection occurs before bending failure. Short, fat cantilever versus long and skinny. The main types of piping stresses There are five primary piping stresses that can cause failure in a piping system: hoop stress, axial stress, bending stress, torsional stress, and fatigue stress.

Hoop stress is the result of pressure being applied to the pipe either internally or externally. Because pressure is uniformly applied to the piping system, hoop stress also is considered to be uniform over a given length of pipe. Note that hoop stress will change with diameter and wall thickness throughout the piping system. Hoop stress is most commonly represented by the following formula: Axial stress results from the restrained axial growth of the pipe.

Axial growth is caused by thermal expansion, pressure expansion, and applied forces. If a pipe run can grow freely in one direction, there is no axial present—at least in theory.

When comparing axial growth caused by pressure, steel-pipe growth is minimal at over ft and can be ignored. Composite piping such as fiber re-enforced pipe FRP or plastic pipe will exhibit noticeable growth, as much as 2 to 3 in. The primary reason for the difference in growth rates under pressure is related to the modulus of elasticity. Steel has a modulus of elasticity of approximately 30 x psi, whereas composites will be 2 to 3 orders of magnitude or less.

Axial stress is represented by the axial force over the pipes cross-sectional area: Bending stress is the stress caused by body forces being applied to the piping. Body forces are the pipe and medium weight, concentrated masses valves, flanges , occasional forces seismic, wind, thrust loads , and forced displacements caused by growth from adjacent piping and equipment connections. Body forces create a resultant moment about the pipe, for which the stress can be represented by the moment divided by the section modulus: Torsional stress is the resultant stress caused by the rotational moment around the pipe axis and is caused by body forces.

Pipe Stress Analysis

However, because a piping system most likely will fail in bending before torsion, most piping codes ignore the effects of torsion. Fatigue stress is created by continuous cycling of the stresses that are present in the piping. For example, turning a water faucet on and off all day will create a fatigue stress, albeit low, because of the pressure being released and then built up.

Fatigue stress results in a reduction of allowable strength in the piping system and is commonly caused by cycling of: Pressure. Vibration, flow induced or cause by rotating equipment.

Occasional loads a gentle breeze caused the Tacoma Narrows Bridge in Washington State to collapse from fatigue.

Allowable code stresses Piping codes, such as those published by ASME, provide an allowable code stress, which is the maximum stress a piping system can withstand before code failure.

A code failure is not necessarily a piping failure. This is because of safety factors built into piping codes. ASME codes consider three distinct types of stress: sustained stress, displacement thermal or expansion stress, and occasional stress.

Sustained or longitudinal stress is developed by imposing loads necessary to satisfy the laws of equilibrium between external and internal forces. Sustained stresses are not self-limiting.

If the sustained stress exceeds the yield strength of the piping material through the entire thickness, the prevention of failure is entirely dependent on the strain-hardening properties of the material.

Displacement stress is developed by the self-constraint of the piping structure. It must satisfy an imposed strain pattern rather than being in equilibrium with an external load.